# Patent

## Title
Isolated mouse or human cell having an exogenous transgene in an endogenous albumin gene

## Abstract

Cells and methods of using these cells for expressing a transgene expressing a protein that is aberrantly expressed in a metabolic disorders from a safe harbor locus.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims the benefit of U.S. Provisional Application No. 61/733,652, filed Dec. 5, 2012, the disclosure of which is hereby incorporated by reference in its entirety.


TECHNICAL FIELD
The present disclosure is in the field of genome editing.
BACKGROUND
Gene therapy holds enormous potential for a new era of human therapeutics. These methodologies will allow treatment for conditions that have not been addressable by standard medical practice. Gene therapy can include the many variations of genome editing techniques such as disruption or correction of a gene locus, and insertion of an expressible transgene that can be controlled either by a specific exogenous promoter fused to the transgene, or by the endogenous promoter found at the site of insertion into the genome.
Delivery and insertion of the transgene are examples of hurdles that must be solved for any real implementation of this technology. For example, although a variety of gene delivery methods are potentially available for therapeutic use, all involve substantial tradeoffs between safety, durability and level of expression. Methods that provide the transgene as an episome (e.g. basic adenovirus, AAV and plasmid-based systems) are generally safe and can yield high initial expression levels, however, these methods lack robust episome replication, which may limit the duration of expression in mitotically active tissues. In contrast, delivery methods that result in the random integration of the desired transgene (e.g. integrating lentivirus) provide more durable expression but, due to the untargeted nature of the random insertion, may provoke unregulated growth in the recipient cells, potentially leading to malignancy via activation of oncogenes in the vicinity of the randomly integrated transgene cassette. Moreover, although transgene integration avoids replication-driven loss, it does not prevent eventual silencing of the exogenous promoter fused to the transgene. Over time, such silencing results in reduced transgene expression for the majority of random insertion events. In addition, integration of a transgene rarely occurs in every target cell, which can make it difficult to achieve a high enough expression level of the transgene of interest to achieve the desired therapeutic effect.
In recent years, a new strategy for transgene integration has been developed that uses cleavage with site-specific nucleases to bias insertion into a chosen genomic locus (see, e.g., co-owned U.S. Pat. No. 7,888,121). This approach offers the prospect of improved transgene expression, increased safety and expressional durability, as compared to classic integration approaches, since it allows exact transgene positioning for a minimal risk of gene silencing or activation of nearby oncogenes.
One approach involves the integration of a transgene into its cognate locus, for example, insertion of a wild type transgene into the endogenous locus to correct a mutant gene. Alternatively, the transgene may be inserted into a non-cognate locus chosen specifically for its beneficial properties. See, e.g., U.S. Patent Publication No. 20120128635 relating to targeted insertion of a factor IX (FIX) transgene. Targeting the cognate locus can be useful if one wishes to replace expression of the endogenous gene with the transgene while still maintaining the expressional control exerted by the endogenous regulatory elements. Specific nucleases can be used that cleave within or near the endogenous locus and the transgene can be integrated at the site of cleavage through homology directed repair (HDR) or by end capture during non-homologous end joining (NHEJ). The integration process is determined by the use or non-use of regions of homology in the transgene donors between the donor and the endogenous locus.
Alternatively, the transgene may be inserted into a specific “safe harbor” location in the genome that may either utilize the promoter found at that safe harbor locus, or allow the expressional regulation of the transgene by an exogenous promoter that is fused to the transgene prior to insertion. Several such “safe harbor” loci have been described, including CCR5, HPRT, AAVS1, Rosa and albumin. See, e.g., U.S. Pat. Nos. 7,951,925 and 8,110,379; U.S. Publication Nos. 20080159996; 20100218264; 20120017290; 20110265198; 20130137104; 20130122591; 20130177983 and 20130177960 and 20150056705. As described above, nucleases specific for the safe harbor can be utilized such that the transgene construct is inserted by either HDR- or NHEJ-driven processes.
An especially attractive application of gene therapy involves the treatment of disorders that are either caused by an insufficiency of a secreted gene product or that are treatable by secretion of a therapeutic protein. Such disorders are potentially addressable via delivery of a therapeutic transgene to a modest number of cells, provided that each recipient cell expresses a high level of the therapeutic gene product. In such a scenario, relief from the need for gene delivery to a large number of cells can enable the successful development of gene therapies for otherwise intractable indications. Such applications would require permanent, safe, and very high levels of transgene expression. Thus the development of a safe harbor which exhibits these properties would provide substantial utility in the field of gene therapy.
A considerable number of disorders are either caused by an insufficiency of a secreted gene product or are treatable by secretion of a therapeutic protein. Clotting disorders, alpha-1 antitrypsin (A1AT) deficiency, lysosomal storage diseases and Type I diabetes, for example, are fairly common genetic disorders in which expression of certain proteins is aberrant in some manner, i.e., lack of expression of a protein or production of a mutant protein. See, e.g., U.S. Patent Publication Nos. 20130177983 and 20130177960.
Metabolic diseases are those in which an enzyme involved in a metabolic process is aberrant, resulting in either a build-up in a metabolic precursor and/or lack of production of a needed metabolic product. These diseases are often autosomally recessive. Metabolic diseases that are caused by aberrant protein production include, methylmalonic acidemia, propionic acidemia, glycogen storage diseases type 1, familial hypercholesterolemia (FH) is a common genetic and metabolic disease, urea cycle disorders (e.g., citrullinemia or OTC deficiency), Crigler Najjar Syndrome (CNS), Gilbert syndrome, hepatorenal tyrosinemia, primary hyperoxaluria. transthyretin gene (TTR)-mediated amyloidosis (ATTR), Wilson's disease, phenylketonuria (PKU), and familial lipoprotein lipase deficiency (LPLD).
Treatment options for metabolic disorders are currently very limited. For instance, in familial hypercholesterolemia (FH patients, several defects can cause an abnormal level of serum cholesterol and can be associated with early onset cardiovascular disease. Treatment for FH usually involves the use of statins, but even when statins reduce the patient's serum cholesterol down to a normal level, the patients still have a higher risk of cardiovascular disease. In addition, statin use in FH patients that are heterozygous for their defect may be more successful that treatment of patients that are homozygotes. In another example, PKU patients must follow a strict diet avoiding foods containing aromatic amino acids, sometimes for life to avoid the build-up of phenylalanine, since these patients are unable to expression the enzyme phenylalanine hydroxyylase and convert phenylalanine to tyrosine naturally.
Albumin is a protein that is produced in the liver and secreted into the blood. In humans, serum albumin comprises 60% of the protein found in blood, and its function seems to be to regulate blood volume by regulating the colloid osmotic pressure. It also serves as a carrier for molecules with low solubility, for example lipid soluble hormones, bile salts, free fatty acids, calcium and transferrin. In addition, serum albumin carries therapeutics, including warfarin, phenobutazone, clofibrate and phenytoin. In humans, albumin is highly expressed, resulting in the production of approximately 15 g of albumin protein each day. Albumin has no autocrine function, and there does not appear to be any phenotype associated with monoallelic knockouts and only mild phenotypic observations are found for biallelic knockouts (see Watkins et at (1994) Proc Natl Acad Sci USA 91:9417). See, also, U.S. Patent Publication Nos. 20130177983 and 20130177960.
Albumin has also been used when coupled to therapeutic reagents to increase the serum half-life of the therapeutic. For example, Osborn et al (J Pharm Exp Thera (2002) 303(2):540) disclose the pharmacokinetics of a serum albumin-interferon alpha fusion protein and demonstrate that the fusion protein had an approximate 140-fold slower clearance such that the half-life of the fusion was 18-fold longer than for the interferon alpha protein alone. Other examples of therapeutic proteins recently under development that are albumin fusions include Albulin-GTM, CardevaTM and AlbugraninTM (Teva Pharmaceutical Industries, fused to Insulin, b-type natriuretic, or GCSF, respectively), Syncria® (GlaxoSmithKline, fused to Glucagon-like peptide-1) and Albuferon α-2B, fused to IFN-alpha (see Current Opinion in Drug Discovery and Development, (2009), vol 12, No. 2. p. 288). In these cases, Albulin-GTM, CardevaTM and Syncria® are all fusion proteins where the albumin is found on the N-terminus of the fusion, while AlbugraninTM and Albuferon alpha 2G are fusions where the albumin is on the C-terminus of the fusion.
Thus, there remains a need for additional methods and compositions that can be used to express a desired transgene at a therapeutically relevant level, while avoiding any associated toxicity, and which may limit expression of the transgene to the desired tissue type, for example to treat metabolic diseases.
SUMMARY
Disclosed herein are methods and compositions for creating a safe harbor in the genome of cells, for targeted insertion and subsequence expression of a transgene, for example expression of the transgene from a secretory tissue such as liver.
In one aspect, described herein is a cell comprising a transgene encoding a functional version of a protein that is aberrantly expressed in a metabolic disease, wherein the transgene is integrated site-specifically using a nuclease into an endogenous safe harbor gene. The nuclease cleaves the endogenous gene and the transgene is integrated in a targeted manner at or near the nuclease target site(s). In certain embodiments, the safe harbor gene is a CCR5, HPRT, AAVS1, Rosa or albumin gene. See, e.g., U.S. Pat. Nos. 7,951,925 and 8,110,379; U.S. Publication Nos. 20080159996; 201000218264; 20120017290; 20110265198; 20130137104; 20130122591; 20130177983 and 20130177960 and U.S. Provisional Application No. 61/823,689).
Cleavage can occur through the use of specific nucleases such as engineered zinc finger nucleases (ZFN), transcription-activator like effector nucleases (TALENs), or using the CRISPR/Cas system with an engineered crRNA/tracr RNA (‘single guide RNA’) to guide specific cleavage. In some embodiments, two nickases are used to create a DSB by introducing two nicks. In some cases, the nickase is a ZFN, while in others, the nickase is a TALEN or a CRISPR/Cas system. Targeted integration may occur via homology directed repair mechanisms (HDR) and/or via non-homology repair mechanisms (e.g., NHEJ donor capture).
In another aspect, a method of modifying a cell to express a transgene encoding a protein that is lacking, non-functional or exhibits reduced expression as compared to wild-type in a subject with a metabolic disorder is provided, the method comprising integrating the transgene into a safe harbor gene of the cell using one or more nucleases. In certain embodiments, the endogenous safe harbor gene is an albumin gene. In certain embodiments, the methods of genetically modifying a cell to produce one or more proteins that are aberrantly expressed in a subject with a metabolic disorder, comprise cleaving an endogenous safe harbor gene in the cell using one or more nucleases (e.g., ZFNs, TALENs, CRISPR/Cas) such that a transgene encoding the proteins are integrated into the safe harbor locus and expressed in the cell. In certain embodiments, the safe harbor gene is a CCR5, HPRT, AAVS1, Rosa or albumin gene. In some embodiments, the nuclease(s) are delivered to the cell using a vector, and in some instances, the vector is a viral vector. In other embodiments, the nuclease(s) are delivered to the cell as mRNAs.
In other aspect, a method of providing one or more protein products that are aberrantly expressed in a subject with a metabolic disease, the method comprising modifying a cell of the subject as described herein to comprise transgene encoding the protein product(s)) into an endogenous safe harbor gene in the cell of the subject. In certain embodiments, the method comprises providing a genetically modified cell as described herein (comprising a transgene encoding protein aberrantly expressed in a metabolic disorder) to the subject. In other embodiments, the method comprises administering one or more nucleases (or one or more vectors encoding the nucleases) and a donor comprising a transgene encoding a protein aberrantly expressed in a metabolic disorder to the subject, such that the transgene is integrated and expressed in a cell of the subject. Thus, an isolated, modified cell may be introduced into the subject (ex vivo) or the cell may be modified when it is part of the subject (in vivo). Also provided is the use of the donors and/or nucleases described herein for the treatment of a metabolic disorder, for example, in the preparation of medicament for treatment of a metabolic disorder.
In any of the compositions (e.g., cells) or methods described herein, the metabolic disease may be for example, methylmalonic acidemia, propionic acidemia, glycogen storage disease type 1, familial hypercholesterolemia (FH), a urea cycle disorder, Crigler Najjar Syndrome (CNS), Gilbert syndrome, hepatorenal tyrosinemia, primary hyperoxaluria, transthyretin gene (TTR)-mediated amyloidosis (ATTR), Wilson's disease, phenylketonuria (PKU), and/or familial lipoprotein lipase deficiency (LPLD).
Furthermore, in any of the compositions (e.g., cells) or methods described herein, the transgene may encode one or more of the following proteins: MMAA, MMAB, MMACHC, MMADHC (C2orf25), MTRR, LMBRD1, MTR, propionyl-CoA carboxylase (PCC) (PCCA and/or PCCB subunits), a glucose-6-phosphate transporter (G6PT) protein or glucose-6-phosphatase (G6Pase), an LDL receptor (LDLR), an ApoB protein, an LDLRAP-1 protein, a PCSK9 protein, a mitochondrial protein such as NAGS (N-acetylglutamate synthetase), CPS1 (carbamoyl phosphate synthetase I), and OTC (ornithine transcarbamylase), ASS (argininosuccinic acid synthetase), ASL (argininosuccinase acid lyase) and/or ARG1 (arginase), and/or a solute carrier family 25 (SLC25A13, an aspartate/glutamate carrier) protein, a UGT1A1 or UDP glucuronsyltransferase polypeptide A1, a fumarylacetoacetate hydrolyase (FAH), an alanine-glyoxylate aminotransferase (AGXT) protein, a glyoxylate reductase/hydroxypyruvate reductase (GRHPR) protein, a transthyretin gene (TTR) protein, an ATP7B protein, a phenylalanine hydroxylase (PAH) protein and/or a lipoprotein lyase (LPL) protein.
In any of the compositions and methods described herein, non-limiting examples of suitable cells include eukaryotic cells or cell lines such as secretory cells (e.g., liver cells, mucosal cells, salivary gland cells, pituitary cells, etc.), blood cells (red blood cells), red blood precursory cells, hepatic cells, embryonic stem cells, induced pluripotent stem cells, hepatic stem cells, and hematopoietic stem cells (e.g., CD34+). The cell can also comprise an embryo cell, for example, of a mouse, rat, rabbit or other mammal cell embryo. The cell may be isolated or may be part of an organism (e.g., subject).
In any of the compositions and methods described herein, the transgene may be integrated into the endogenous safe harbor gene such that some, all or none of the endogenous gene is expressed, for example a fusion protein with the integrated transgene. In some embodiments, the endogenous safe harbor gene is an albumin gene and the endogenous sequences are albumin sequences. The endogenous may be present on the amino (N)-terminal portion of the exogenous protein and/or on the carboxy (C)-terminal portion of the exogenous protein. The albumin sequences may include full-length wild-type or mutant albumin sequences or, alternatively, may include partial albumin amino acid sequences. In certain embodiments, the albumin sequences (full-length or partial) serve to increase the serum half-life of the polypeptide expressed by the transgene to which it is fused and/or as a carrier. In other embodiments, the transgene comprises albumin sequences and is targeted for insertion into another safe harbor within a genome. Furthermore, the transgene may include an exogenous promoter (e.g., constitutive or inducible promoter) that drives its expression or its expression may be driven by endogenous control sequences (e.g., endogenous albumin promoter).
The nucleases as described herein (e.g., ZFNs, TALENs, CRISPR/Cas systems) may be introduced as proteins and/or polynucleotides encoding the nucleases. The polynucleotide may be, for example, mRNA. In some aspects, the mRNA may be chemically modified (See e.g. Kormann et al, (2011) Nature Biotechnology 29(2):154-157).
In some embodiments, the methods of the invention may be used in vivo in transgenic animal systems. In some aspects, the transgenic animal may be used in model development where the transgene encodes a human gene. In some instances, the transgenic animal may be knocked out at the corresponding endogenous locus, allowing the development of an in vivo system where the human protein may be studied in isolation. Such transgenic models may be used for screening purposes to identify small molecule, large biomolecules or other entities which may interact or modify the human protein of interest. In other aspects, the transgenic animals may be used for production purposes, for example, to produce antibodies or other biomolecules of interest. In certain embodiments, the animal is a small mammal, for example a dog, rabbit or a rodent such as rat, a mouse or a guinea pig. In other embodiments, the animal is a non-human primate. In yet further embodiments, the animal is a farm animal such as a cow, goat or pig. In some aspects, the transgene is integrated into the selected locus (e.g., albumin or safe-harbor) into a stem cell (e.g., an embryonic stem cell, an induced pluripotent stem cell, a hepatic stem cell, etc.) or animal embryo obtained by any of the methods described herein, and then the embryo is implanted such that a live animal is born. The animal is then raised to sexual maturity and allowed to produce offspring wherein at least some of the offspring comprise the integrated transgene.
In any of the methods or compositions described herein, the cell containing the engineered locus (e.g., an albumin locus) can be a stem cell. Specific stem cell types that may be used with the methods and compositions of the invention include embryonic stem cells (ESC), induced pluripotent stem cells (iPSC) and hepatic or liver stem cells. The iPSCs can be derived from patient samples and from normal controls wherein the patient derived iPSC can be mutated to normal gene sequence at the gene of interest, or normal cells can be altered to the known disease allele at the gene of interest. Similarly, the hepatic stem cells can be isolated from a patient. These cells are then engineered to express the transgene of interest, expanded and then reintroduced into the patient.
Also provided herein is a method of treating and/or preventing a condition associated with aberrant expression of a protein involved in a metabolic disease. In certain embodiments, the method comprises introducing, via nuclease-mediated targeted integration into a safe harbor gene of a cell (e.g., iPSC, stem cell, etc.) as described herein, one or more functional versions of the proteins exhibiting aberrant expression in the cell or subject, such that the protein is produced and the condition is treated and/or prevented. The methods may be performed ex vivo (e.g., in an isolated cell that is reintroduced into a subject) or in vivo. In certain embodiments, the condition is a metabolic disorder, for example, Methylmalonic academia, Propionic academia, Glycogen storage diseases, Familial hypercholesterolemia (FH), metabolic diseases involving the urea cycle (e.g., citrullinemia or OTC deficiency), Crigler Najjar Syndrome (CNS), Gilbert syndrome, Hepatorenal tyrosinemia (also called Type 1 tyrosinemia), Wilson's disease (or hepatolenticular degeneration), Phenylketonuria (PKU), and/or familial lipoprotein lipase deficiency (LPLD). Exemplary liver and other proteins that may be expressed by the transgene, include, but are not limited to, PCCA, PCCB, MMAA, MMAB, MMACHC, MMADHC (C2orf25), MTRR, LMBRD1, MTR, soluble plasma fibronectin, C-reactive protein, globulins, Factors I-VII, VIII, IX, XI, XII, XIII, vWF, α2-macroglobulin, α1-antitrypsin, antithrombin III, Protein S, Protein C, fibrinolysis, α2-antiplasmin, Complement components C1-9, Complement component 3 (C3), ceruloplasmin (carries copper), transcortin (carries cortisol, aldosterone and progesterone), haptoglobin (carries free hemoglobin released from erythrocytes), hemopexin (carries free heme released from hemoglobin), IGF binding protein, urinary proteins, retinol binding protein, sex hormone-binding globulin, thyroxine-binding globulin, transthyretin, transferrin, carries iron ions in the ferric form (Fe3+), Vitamin D binding protein, Insulin-like growth factor 1, thrombopoietin, prohormones, angiotensinogen, and apolipoproteins (except apo B48).
Also provided is an embryo comprising at least one DNA vector, wherein the DNA vector comprises an upstream sequence and a downstream sequence flanking the nucleic acid sequence to be integrated, and at least one RNA molecule encoding a zinc finger nuclease that recognizes the chromosomal site of integration. Organisms derived from any of the embryos as described herein are also provided (e.g., embryos that are allowed to develop to sexual maturity and produce progeny).
In another aspect provided by the methods and compositions of the invention is the use of cells, cell lines and animals (e.g., transgenic animals) in the screening of drug libraries and/or other therapeutic compositions (i.e., antibodies, structural RNAs, etc.) for use in treatment of an animal afflicted with a metabolic disorder. Such screens can begin at the cellular level with manipulated cell lines or primary cells, and can progress up to the level of treatment of a whole animal (e.g., human).
A kit, comprising the compositions (e.g., genetically modified cells, ZFPs, CRISPR/Cas system and/or TALENs) of the invention, is also provided. The kit may comprise nucleic acids encoding the nucleases, (e.g. RNA molecules or nuclease-encoding genes contained in a suitable expression vector), donor molecules, suitable host cell lines, instructions for performing the methods of the invention, and the like.
These and other aspects will be readily apparent to the skilled artisan in light of disclosure as a whole.


DETAILED DESCRIPTION
Disclosed herein are compositions and methods for modifying a cell to produce one or more functional versions of proteins whose wild-type expression is aberrant (e.g., not expressed, expressed at low levels, and/or a non-functional or protein of reduced function expressed) in a metabolic disorder. The cell is modified by targeted insertion of a transgene encoding one or more of the proteins into a safe harbor gene (e.g., albumin) of the cell. In some embodiments, the transgene is inserted into an endogenous albumin gene to allow for very high expression levels that are moreover limited to hepatic tissue. The transgene can encode any protein or peptide including those providing therapeutic benefit.
The transgene can be introduced into patient derived cells, e.g. patient derived induced pluripotent stem cells (iPSCs) or other types of stem cells (embryonic, hematopoietic, neural, or mesenchymal as a non-limiting set) for use in eventual implantation into secretory tissues. The transgene can be introduced into any region of interest in these cells, including, but not limited to, into an albumin gene or a safe harbor gene. These altered stem cells can be differentiated for example, into hepatocytes and implanted into the liver. Alternately, the transgene can be directed to the secretory tissue as desired through the use of viral or other delivery systems that target specific tissues. For example, use of the liver-trophic adenovirus associated virus (AAV) vector AAV8 as a delivery vehicle can result in the integration of the transgene at the desired locus when specific nucleases are co-delivered with the transgene.
General
Practice of the methods, as well as preparation and use of the compositions disclosed herein employ, unless otherwise indicated, conventional techniques in molecular biology, biochemistry, chromatin structure and analysis, computational chemistry, cell culture, recombinant DNA and related fields as are within the skill of the art. These techniques are fully explained in the literature. See, for example, Sambrook et al. MOLECULAR CLONING: A LABORATORY MANUAL, Second edition, Cold Spring Harbor Laboratory Press, 1989 and Third edition, 2001; Ausubel et al., CURRENT PROTOCOLS IN MOLECULAR BIOLOGY, John Wiley & Sons, New York, 1987 and periodic updates; the series METHODS IN ENZYMOLOGY, Academic Press, San Diego; Wolffe, CHROMATIN STRUCTURE AND FUNCTION, Third edition, Academic Press, San Diego, 1998; METHODS IN ENZYMOLOGY, Vol. 304, “Chromatin” (P. M. Wassarman and A. P. Wolffe, eds.), Academic Press, San Diego, 1999; and METHODS IN MOLECULAR BIOLOGY, Vol. 119, “Chromatin Protocols” (P. B. Becker, ed.) Humana Press, Totowa, 1999.
Definitions
The terms “nucleic acid,” “polynucleotide,” and “oligonucleotide” are used interchangeably and refer to a deoxyribonucleotide or ribonucleotide polymer, in linear or circular conformation, and in either single- or double-stranded form. For the purposes of the present disclosure, these terms are not to be construed as limiting with respect to the length of a polymer. The terms can encompass known analogues of natural nucleotides, as well as nucleotides that are modified in the base, sugar and/or phosphate moieties (e.g., phosphorothioate backbones). In general, an analogue of a particular nucleotide has the same base-pairing specificity; i.e., an analogue of A will base-pair with T.
The terms “polypeptide,” “peptide” and “protein” are used interchangeably to refer to a polymer of amino acid residues. The term also applies to amino acid polymers in which one or more amino acids are chemical analogues or modified derivatives of corresponding naturally-occurring amino acids.
“Binding” refers to a sequence-specific, non-covalent interaction between macromolecules (e.g., between a protein and a nucleic acid). Not all components of a binding interaction need be sequence-specific (e.g., contacts with phosphate residues in a DNA backbone), as long as the interaction as a whole is sequence-specific. Such interactions are generally characterized by a dissociation constant (Kd) of 10−6 M−1 or lower. “Affinity” refers to the strength of binding: increased binding affinity being correlated with a lower Kd.
A “binding protein” is a protein that is able to bind non-covalently to another molecule. A binding protein can bind to, for example, a DNA molecule (a DNA-binding protein), an RNA molecule (an RNA-binding protein) and/or a protein molecule (a protein-binding protein). In the case of a protein-binding protein, it can bind to itself (to form homodimers, homotrimers, etc.) and/or it can bind to one or more molecules of a different protein or proteins. A binding protein can have more than one type of binding activity. For example, zinc finger proteins have DNA-binding, RNA-binding and protein-binding activity.
A “zinc finger DNA binding protein” (or binding domain) is a protein, or a domain within a larger protein, that binds DNA in a sequence-specific manner through one or more zinc fingers, which are regions of amino acid sequence within the binding domain whose structure is stabilized through coordination of a zinc ion. The term zinc finger DNA binding protein is often abbreviated as zinc finger protein or ZFP.
A “TALE DNA binding domain” or “TALE” is a polypeptide comprising one or more TALE repeat domains/units. The repeat domains are involved in binding of the TALE to its cognate target DNA sequence. A single “repeat unit” (also referred to as a “repeat”) is typically 33-35 amino acids in length and exhibits at least some sequence homology with other TALE repeat sequences within a naturally occurring TALE protein. See, e.g., U.S. Pat. No. 8,586,526, incorporated by reference herein in its entirety.
Zinc finger and TALE binding domains can be “engineered” to bind to a predetermined nucleotide sequence, for example via engineering (altering one or more amino acids) of the recognition helix region of a naturally occurring zinc finger or TALE protein. Therefore, engineered DNA binding proteins (zinc fingers or TALEs) are proteins that are non-naturally occurring. Non-limiting examples of methods for engineering DNA-binding proteins are design and selection. A designed DNA binding protein is a protein not occurring in nature whose design/composition results principally from rational criteria. Rational criteria for design include application of substitution rules and computerized algorithms for processing information in a database storing information of existing ZFP and/or TALE designs and binding data. See, for example, U.S. Pat. Nos. 6,140,081; 6,453,242; and 6,534,261; see also WO 98/53058; WO 98/53059; WO 98/53060; WO 02/016536 and WO 03/016496 and U.S. Pat. No. 8,586,526.
A “selected” zinc finger protein or TALE is a protein not found in nature whose production results primarily from an empirical process such as phage display, interaction trap or hybrid selection. See e.g., U.S. Pat. No. 5,789,538; U.S. Pat. No. 5,925,523; U.S. Pat. No. 6,007,988; U.S. Pat. No. 6,013,453; U.S. Pat. No. 6,200,759; WO 95/19431; WO 96/06166; WO 98/53057; WO 98/54311; WO 00/27878; WO 01/60970 WO 01/88197; WO 02/099084 and U.S. Pat. No. 8,586,526.
“Recombination” refers to a process of exchange of genetic information between two polynucleotides. For the purposes of this disclosure, “homologous recombination (HR)” refers to the specialized form of such exchange that takes place, for example, during repair of double-strand breaks in cells via homology-directed repair mechanisms. This process requires nucleotide sequence homology, uses a “donor” molecule to template repair of a “target” molecule (i.e., the one that experienced the double-strand break), and is variously known as “non-crossover gene conversion” or “short tract gene conversion,” because it leads to the transfer of genetic information from the donor to the target. Without wishing to be bound by any particular theory, such transfer can involve mismatch correction of heteroduplex DNA that forms between the broken target and the donor, and/or “synthesis-dependent strand annealing,” in which the donor is used to re-synthesize genetic information that will become part of the target, and/or related processes. Such specialized HR often results in an alteration of the sequence of the target molecule such that part or all of the sequence of the donor polynucleotide is incorporated into the target polynucleotide.
In the methods of the disclosure, one or more targeted nucleases as described herein create a double-stranded break in the target sequence (e.g., cellular chromatin) at a predetermined site, and a “donor” polynucleotide, having homology to the nucleotide sequence in the region of the break, can be introduced into the cell. The presence of the double-stranded break has been shown to facilitate integration of the donor sequence. The donor sequence may be physically integrated or, alternatively, the donor polynucleotide is used as a template for repair of the break via homologous recombination, resulting in the introduction of all or part of the nucleotide sequence as in the donor into the cellular chromatin. Thus, a first sequence in cellular chromatin can be altered and, in certain embodiments, can be converted into a sequence present in a donor polynucleotide. Thus, the use of the terms “replace” or “replacement” can be understood to represent replacement of one nucleotide sequence by another, (i.e., replacement of a sequence in the informational sense), and does not necessarily require physical or chemical replacement of one polynucleotide by another.
In any of the methods described herein, additional pairs of zinc-finger or TALEN proteins can be used for additional double-stranded cleavage of additional target sites within the cell.
In certain embodiments of methods for targeted recombination and/or replacement and/or alteration of a sequence in a region of interest in cellular chromatin, a chromosomal sequence is altered by homologous recombination with an exogenous “donor” nucleotide sequence. Such homologous recombination is stimulated by the presence of a double-stranded break in cellular chromatin, if sequences homologous to the region of the break are present.
In any of the methods described herein, the first nucleotide sequence (the “donor sequence”) can contain sequences that are homologous, but not identical, to genomic sequences in the region of interest, thereby stimulating homologous recombination to insert a non-identical sequence in the region of interest. Thus, in certain embodiments, portions of the donor sequence that are homologous to sequences in the region of interest exhibit between about 80 to 99% (or any value therebetween) sequence identity to the genomic sequence that is replaced. In other embodiments, the homology between the donor and genomic sequence is higher than 99%, for example if only 1 nucleotide differs as between donor and genomic sequences of over 101 contiguous base pairs. In certain cases, a non-homologous portion of the donor sequence can contain sequences not present in the region of interest, such that new sequences are introduced into the region of interest. In these instances, the non-homologous sequence is generally flanked by sequences of 50-1,000 base pairs (or any integral value therebetween) or any number of base pairs greater than 1,000, that are homologous or identical to sequences in the region of interest. In other embodiments, the donor sequence is non-homologous to the first sequence, and is inserted into the genome by non-homologous recombination mechanisms.
Any of the methods described herein can be used for partial or complete inactivation of one or more target sequences in a cell by targeted integration of donor sequence that disrupts expression of the gene(s) of interest. Cell lines with partially or completely inactivated genes are also provided.
Furthermore, the methods of targeted integration as described herein can also be used to integrate one or more exogenous sequences. The exogenous nucleic acid sequence can comprise, for example, one or more genes or cDNA molecules, or any type of coding or non-coding sequence, as well as one or more control elements (e.g., promoters). In addition, the exogenous nucleic acid sequence may produce one or more RNA molecules (e.g., small hairpin RNAs (shRNAs), inhibitory RNAs (RNAis), microRNAs (miRNAs), etc.).
“Cleavage” refers to the breakage of the covalent backbone of a DNA molecule. Cleavage can be initiated by a variety of methods including, but not limited to, enzymatic or chemical hydrolysis of a phosphodiester bond. Both single-stranded cleavage and double-stranded cleavage are possible, and double-stranded cleavage can occur as a result of two distinct single-stranded cleavage events. DNA cleavage can result in the production of either blunt ends or staggered ends. In certain embodiments, fusion polypeptides are used for targeted double-stranded DNA cleavage.
A “cleavage half-domain” is a polypeptide sequence which, in conjunction with a second polypeptide (either identical or different) forms a complex having cleavage activity (preferably double-strand cleavage activity). The terms “first and second cleavage half-domains;” “+ and − cleavage half-domains” and “right and left cleavage half-domains” are used interchangeably to refer to pairs of cleavage half-domains that dimerize.
An “engineered cleavage half-domain” is a cleavage half-domain that has been modified so as to form obligate heterodimers with another cleavage half-domain (e.g., another engineered cleavage half-domain). See, also, U.S. Patent Publication Nos. 2005/0064474, 20070218528, 2008/0131962 and 2011/0201055, incorporated herein by reference in their entireties.
The term “sequence” refers to a nucleotide sequence of any length, which can be DNA or RNA; can be linear, circular or branched and can be either single-stranded or double stranded. The term “donor sequence” or “transgene” refers to a nucleotide sequence that is inserted into a genome. A donor sequence can be of any length, for example between 2 and 10,000 nucleotides in length (or any integer value therebetween or thereabove), preferably between about 100 and 1,000 nucleotides in length (or any integer therebetween), more preferably between about 200 and 500 nucleotides in length. The transgene can produce a DNA and/or RNA molecule.
“Chromatin” is the nucleoprotein structure comprising the cellular genome. Cellular chromatin comprises nucleic acid, primarily DNA, and protein, including histones and non-histone chromosomal proteins. The majority of eukaryotic cellular chromatin exists in the form of nucleosomes, wherein a nucleosome core comprises approximately 150 base pairs of DNA associated with an octamer comprising two each of histones H2A, H2B, H3 and H4; and linker DNA (of variable length depending on the organism) extends between nucleosome cores. A molecule of histone H1 is generally associated with the linker DNA. For the purposes of the present disclosure, the term “chromatin” is meant to encompass all types of cellular nucleoprotein, both prokaryotic and eukaryotic. Cellular chromatin includes both chromosomal and episomal chromatin.
A “chromosome,” is a chromatin complex comprising all or a portion of the genome of a cell. The genome of a cell is often characterized by its karyotype, which is the collection of all the chromosomes that comprise the genome of the cell. The genome of a cell can comprise one or more chromosomes.
An “episome” is a replicating nucleic acid, nucleoprotein complex or other structure comprising a nucleic acid that is not part of the chromosomal karyotype of a cell. Examples of episomes include plasmids and certain viral genomes.
A “target site” or “target sequence” is a nucleic acid sequence that defines a portion of a nucleic acid to which a binding molecule will bind, provided sufficient conditions for binding exist.
An “exogenous” molecule is a molecule that is not normally present in a cell, but can be introduced into a cell by one or more genetic, biochemical or other methods. “Normal presence in the cell” is determined with respect to the particular developmental stage and environmental conditions of the cell. Thus, for example, a molecule that is present only during embryonic development of muscle is an exogenous molecule with respect to an adult muscle cell. Similarly, a molecule induced by heat shock is an exogenous molecule with respect to a non-heat-shocked cell. An exogenous molecule can comprise, for example, a functioning version of a malfunctioning endogenous molecule or a malfunctioning version of a normally-functioning endogenous molecule.
An exogenous molecule can be, among other things, a small molecule, such as is generated by a combinatorial chemistry process, or a macromolecule such as a protein, nucleic acid, carbohydrate, lipid, glycoprotein, lipoprotein, polysaccharide, any modified derivative of the above molecules, or any complex comprising one or more of the above molecules. Nucleic acids include DNA and RNA, can be single- or double-stranded; can be linear, branched or circular; and can be of any length. Nucleic acids include those capable of forming duplexes, as well as triplex-forming nucleic acids. See, for example, U.S. Pat. Nos. 5,176,996 and 5,422,251. Proteins include, but are not limited to, DNA-binding proteins, transcription factors, chromatin remodeling factors, methylated DNA binding proteins, polymerases, methylases, demethylases, acetylases, deacetylases, kinases, phosphatases, integrases, recombinases, ligases, topoisomerases, gyrases and helicases.
An exogenous molecule can be the same type of molecule as an endogenous molecule, e.g., an exogenous protein or nucleic acid. For example, an exogenous nucleic acid can comprise an infecting viral genome, a plasmid or episome introduced into a cell, or a chromosome that is not normally present in the cell. Methods for the introduction of exogenous molecules into cells are known to those of skill in the art and include, but are not limited to, lipid-mediated transfer (i.e., liposomes, including neutral and cationic lipids), electroporation, direct injection, cell fusion, particle bombardment, calcium phosphate co-precipitation, DEAE-dextran-mediated transfer and viral vector-mediated transfer. An exogenous molecule can also be the same type of molecule as an endogenous molecule but derived from a different species than the cell is derived from. For example, a human nucleic acid sequence may be introduced into a cell line originally derived from a mouse or hamster.
By contrast, an “endogenous” molecule is one that is normally present in a particular cell at a particular developmental stage under particular environmental conditions. For example, an endogenous nucleic acid can comprise a chromosome, the genome of a mitochondrion, chloroplast or other organelle, or a naturally-occurring episomal nucleic acid. Additional endogenous molecules can include proteins, for example, transcription factors and enzymes.
A “fusion” molecule is a molecule in which two or more subunit molecules are linked, preferably covalently. The subunit molecules can be the same chemical type of molecule, or can be different chemical types of molecules. Examples of the first type of fusion molecule include, but are not limited to, fusion proteins (for example, a fusion between a ZFP or TALE DNA-binding domain and one or more activation domains) and fusion nucleic acids (for example, a nucleic acid encoding the fusion protein described supra). Examples of the second type of fusion molecule include, but are not limited to, a fusion between a triplex-forming nucleic acid and a polypeptide, and a fusion between a minor groove binder and a nucleic acid.
Expression of a fusion protein in a cell can result from delivery of the fusion protein to the cell or by delivery of a polynucleotide encoding the fusion protein to a cell, wherein the polynucleotide is transcribed, and the transcript is translated, to generate the fusion protein. Trans-splicing, polypeptide cleavage and polypeptide ligation can also be involved in expression of a protein in a cell. Methods for polynucleotide and polypeptide delivery to cells are presented elsewhere in this disclosure.
A “gene,” for the purposes of the present disclosure, includes a DNA region encoding a gene product (see infra), as well as all DNA regions which regulate the production of the gene product, whether or not such regulatory sequences are adjacent to coding and/or transcribed sequences. Accordingly, a gene includes, but is not necessarily limited to, promoter sequences, terminators, translational regulatory sequences such as ribosome binding sites and internal ribosome entry sites, enhancers, silencers, insulators, boundary elements, replication origins, matrix attachment sites and locus control regions.
“Gene expression” refers to the conversion of the information, contained in a gene, into a gene product. A gene product can be the direct transcriptional product of a gene (e.g., mRNA, tRNA, rRNA, antisense RNA, ribozyme, structural RNA or any other type of RNA) or a protein produced by translation of an mRNA. Gene products also include RNAs which are modified, by processes such as capping, polyadenylation, methylation, and editing, and proteins modified by, for example, methylation, acetylation, phosphorylation, ubiquitination, ADP-ribosylation, myristilation, and glycosylation.
“Modulation” of gene expression refers to a change in the activity of a gene. Modulation of expression can include, but is not limited to, gene activation and gene repression. Genome editing (e.g., cleavage, alteration, inactivation, random mutation) can be used to modulate expression. Gene inactivation refers to any reduction in gene expression as compared to a cell that does not include a ZFP or TALEN as described herein. Thus, gene inactivation may be partial or complete.
A “region of interest” is any region of cellular chromatin, such as, for example, a gene or a non-coding sequence within or adjacent to a gene, in which it is desirable to bind an exogenous molecule. Binding can be for the purposes of targeted DNA cleavage and/or targeted recombination. A region of interest can be present in a chromosome, an episome, an organellar genome (e.g., mitochondrial, chloroplast), or an infecting viral genome, for example. A region of interest can be within the coding region of a gene, within transcribed non-coding regions such as, for example, leader sequences, trailer sequences or introns, or within non-transcribed regions, either upstream or downstream of the coding region. A region of interest can be as small as a single nucleotide pair or up to 2,000 nucleotide pairs in length, or any integral value of nucleotide pairs.
“Eukaryotic” cells include, but are not limited to, fungal cells (such as yeast), plant cells, animal cells, mammalian cells and human cells (e.g., T-cells).
“Secretory tissues” are those tissues that secrete products. Examples of secretory tissues that are localized to the gastrointestinal tract include the cells that line the gut, the pancreas, and the gallbladder. Other secretory tissues include the liver, tissues associated with the eye and mucous membranes such as salivary glands, mammary glands, the prostate gland, the pituitary gland and other members of the endocrine system. Additionally, secretory tissues include individual cells of a tissue type which are capable of secretion.
The terms “operative linkage” and “operatively linked” (or “operably linked”) are used interchangeably with reference to a juxtaposition of two or more components (such as sequence elements), in which the components are arranged such that both components function normally and allow the possibility that at least one of the components can mediate a function that is exerted upon at least one of the other components. By way of illustration, a transcriptional regulatory sequence, such as a promoter, is operatively linked to a coding sequence if the transcriptional regulatory sequence controls the level of transcription of the coding sequence in response to the presence or absence of one or more transcriptional regulatory factors. A transcriptional regulatory sequence is generally operatively linked in cis with a coding sequence, but need not be directly adjacent to it. For example, an enhancer is a transcriptional regulatory sequence that is operatively linked to a coding sequence, even though they are not contiguous.
With respect to fusion polypeptides, the term “operatively linked” can refer to the fact that each of the components performs the same function in linkage to the other component as it would if it were not so linked. For example, with respect to a fusion polypeptide in which a ZFP or TALE DNA-binding domain is fused to an activation domain, the ZFP or TALE DNA-binding domain and the activation domain are in operative linkage if, in the fusion polypeptide, the ZFP or TALE DNA-binding domain portion is able to bind its target site and/or its binding site, while the activation domain is able to up-regulate gene expression. When a fusion polypeptide in which a ZFP or TALE DNA-binding domain is fused to a cleavage domain, the ZFP or TALE DNA-binding domain and the cleavage domain are in operative linkage if, in the fusion polypeptide, the ZFP or TALE DNA-binding domain portion is able to bind its target site and/or its binding site, while the cleavage domain is able to cleave DNA in the vicinity of the target site.
A “functional fragment” of a protein, polypeptide or nucleic acid is a protein, polypeptide or nucleic acid whose sequence is not identical to the full-length protein, polypeptide or nucleic acid, yet retains the same function as the full-length protein, polypeptide or nucleic acid. A functional fragment can possess more, fewer, or the same number of residues as the corresponding native molecule, and/or can contain one or more amino acid or nucleotide substitutions. Methods for determining the function of a nucleic acid (e.g., coding function, ability to hybridize to another nucleic acid) are well-known in the art. Similarly, methods for determining protein function are well-known. For example, the DNA-binding function of a polypeptide can be determined, for example, by filter-binding, electrophoretic mobility-shift, or immunoprecipitation assays. DNA cleavage can be assayed by gel electrophoresis. See Ausubel et al., supra. The ability of a protein to interact with another protein can be determined, for example, by co-immunoprecipitation, two-hybrid assays or complementation, both genetic and biochemical. See, for example, Fields et al. (1989) Nature 340:245-246; U.S. Pat. No. 5,585,245 and PCT WO 98/44350.
A “vector” is capable of transferring gene sequences to target cells. Typically, “vector construct,” “expression vector,” and “gene transfer vector,” mean any nucleic acid construct capable of directing the expression of a gene of interest and which can transfer gene sequences to target cells. Thus, the term includes cloning, and expression vehicles, as well as integrating vectors.
The terms “metabolic disease,” “metabolic disorder” and “metabolic syndrome” are used interchangeably to refer to any condition in which there is a defect of metabolism, typically due to a genetic defect. Non-limiting examples of metabolic processes that can be impacted include carbohydrate, protein, and/or fat metabolic pathways in food to release energy, transformation of excess nitrogen into waste products excreted in urine and the breaking down or converting chemicals into other substances and transporting them inside cells.
A “reporter gene” or “reporter sequence” refers to any sequence that produces a protein product that is easily measured, preferably although not necessarily in a routine assay. Suitable reporter genes include, but are not limited to, sequences encoding proteins that mediate antibiotic resistance (e.g., ampicillin resistance, neomycin resistance, G418 resistance, puromycin resistance), sequences encoding colored or fluorescent or luminescent proteins (e.g., green fluorescent protein, enhanced green fluorescent protein, red fluorescent protein, luciferase), and proteins which mediate enhanced cell growth and/or gene amplification (e.g., dihydrofolate reductase). Epitope tags include, for example, one or more copies of FLAG, His, myc, Tap, HA or any detectable amino acid sequence. “Expression tags” include sequences that encode reporters that may be operably linked to a desired gene sequence in order to monitor expression of the gene of interest.
Nucleases
Described herein are compositions, particularly nucleases, which are useful targeting a gene for the insertion of a transgene, for example, nucleases that are specific for albumin. In certain embodiments, the nuclease is naturally occurring. In other embodiments, the nuclease is non-naturally occurring, i.e., engineered in the DNA-binding domain and/or cleavage domain. For example, the DNA-binding domain of a naturally-occurring nuclease may be altered to bind to a selected target site (e.g., a meganuclease that has been engineered to bind to site different than the cognate binding site). In other embodiments, the nuclease comprises heterologous DNA-binding and cleavage domains (e.g., zinc finger nucleases; TAL-effector nucleases; meganuclease DNA-binding domains with heterologous cleavage domains).
A. DNA-Binding Domains
Any DNA-binding domain can be used in the compositions and methods disclosed herein, including but not limited to a zinc finger DNA-binding domain, a TALE DNA binding domain, the DNA-binding portion of a CRISPR/Cas nuclease, or a DNA-binding domain from a meganuclease.
In other embodiments, the DNA-binding domain comprises a naturally occurring or engineered (non-naturally occurring) TALE DNA binding domain. See, e.g., U.S. Pat. No. 8,586,526, incorporated by reference in its entirety herein. The plant pathogenic bacteria of the genus Xanthomonas are known to cause many diseases in important crop plants. Pathogenicity of Xanthomonas depends on a conserved type III secretion (T3S) system which injects more than 25 different effector proteins into the plant cell. Among these injected proteins are transcription activator-like effectors (TALE) which mimic plant transcriptional activators and manipulate the plant transcriptome (see Kay et at (2007) Science 318:648-651). These proteins contain a DNA binding domain and a transcriptional activation domain. One of the most well characterized TALEs is AvrBs3 from Xanthomonas campestgris pv. Vesicatoria (see Bonas et at (1989) Mol Gen Genet 218: 127-136 and WO2010079430). TALEs contain a centralized domain of tandem repeats, each repeat containing approximately 34 amino acids, which are key to the DNA binding specificity of these proteins. In addition, they contain a nuclear localization sequence and an acidic transcriptional activation domain (for a review see Schornack S, et al (2006) J Plant Physiol 163(3): 256-272). In addition, in the phytopathogenic bacteria Ralstonia solanacearum two genes, designated brg11 and hpx17 have been found that are homologous to the AvrBs3 family of Xanthomonas in the R. solanacearum biovar 1 strain GMI1000 and in the biovar 4 strain RS1000 (See Heuer et al (2007) Appl and Envir Micro 73(13): 4379-4384). These genes are 98.9% identical in nucleotide sequence to each other but differ by a deletion of 1,575 bp in the repeat domain of hpx17. However, both gene products have less than 40% sequence identity with AvrBs3 family proteins of Xanthomonas. 
Thus, in some embodiments, the DNA binding domain that binds to a target site in a target locus (e.g., albumin or safe harbor) is an engineered domain from a TALE similar to those derived from the plant pathogens Xanthomonas (see Boch et al, (2009) Science 326: 1509-1512 and Moscou and Bogdanove, (2009) Science 326: 1501) and Ralstonia (see Heuer et at (2007) Applied and Environmental Microbiology 73(13): 4379-4384); U.S. Pat. No. 8,586,526 and U.S. Patent Publication No. 20110145940.
In certain embodiments, the DNA binding domain comprises a zinc finger protein (e.g., a zinc finger protein that binds to a target site in an albumin or safe-harbor gene). Preferably, the zinc finger protein is non-naturally occurring in that it is engineered to bind to a target site of choice. See, for example, Beerli et al. (2002) Nature Biotechnol. 20:135-141; Pabo et al. (2001) Ann. Rev. Biochem. 70:313-340; Isalan et al. (2001) Nature Biotechnol. 19:656-660; Segal et al. (2001) Curr. Opin. Biotechnol. 12:632-637; Choo et al. (2000) Curr. Opin. Struct. Biol. 10:411-416; U.S. Pat. Nos. 6,453,242; 6,534,261; 6,599,692; 6,503,717; 6,689,558; 7,030,215; 6,794,136; 7,067,317; 7,262,054; 7,070,934; 7,361,635; 7,253,273; and U.S. Patent Publication Nos. 2005/0064474; 2007/0218528; 2005/0267061, all incorporated herein by reference in their entireties.
An engineered zinc finger binding or TALE domain can have a novel binding specificity, compared to a naturally-occurring zinc finger protein. Engineering methods include, but are not limited to, rational design and various types of selection. Rational design includes, for example, using databases comprising triplet (or quadruplet) nucleotide sequences and individual zinc finger amino acid sequences, in which each triplet or quadruplet nucleotide sequence is associated with one or more amino acid sequences of zinc fingers which bind the particular triplet or quadruplet sequence. See, for example, co-owned U.S. Pat. Nos. 6,453,242 and 6,534,261, incorporated by reference herein in their entireties.
Exemplary selection methods, including phage display and two-hybrid systems, are disclosed in U.S. Pat. Nos. 5,789,538; 5,925,523; 6,007,988; 6,013,453; 6,410,248; 6,140,466; 6,200,759; and 6,242,568; as well as WO 98/37186; WO 98/53057; WO 00/27878; WO 01/88197 and GB 2,338,237. In addition, enhancement of binding specificity for zinc finger binding domains has been described, for example, in co-owned WO 02/077227.
In addition, as disclosed in these and other references, DNA-binding domains (e.g., multi-finger zinc finger proteins or TALE domains) may be linked together using any suitable linker sequences, including for example, linkers of 5 or more amino acids in length. See, also, U.S. Pat. Nos. 6,479,626; 6,903,185; and 7,153,949 for exemplary linker sequences 6 or more amino acids in length. The DNA binding proteins described herein may include any combination of suitable linkers between the individual zinc fingers of the protein. In addition, enhancement of binding specificity for zinc finger binding domains has been described, for example, in co-owned WO 02/077227.
Selection of target sites; DNA-binding domains and methods for design and construction of fusion proteins (and polynucleotides encoding same) are known to those of skill in the art and described in detail in U.S. Pat. Nos. 6,140,081; 5,789,538; 6,453,242; 6,534,261; 5,925,523; 6,007,988; 6,013,453; 6,200,759; 8,586,526; WO 95/19431; WO 96/06166; WO 98/53057; WO 98/54311; WO 00/27878; WO 01/60970 WO 01/88197; WO 02/099084; WO 98/53058; WO 98/53059; WO 98/53060; WO 02/016536 and WO 03/016496.
In addition, as disclosed in these and other references, DNA-binding domains (e.g., multi-finger zinc finger proteins) may be linked together using any suitable linker sequences, including for example, linkers of 5 or more amino acids in length. See, also, U.S. Pat. Nos. 6,479,626; 6,903,185; and 7,153,949 for exemplary linker sequences 6 or more amino acids in length. The proteins described herein may include any combination of suitable linkers between the individual zinc fingers of the protein.
B. Cleavage Domains
Any suitable cleavage domain can be operatively linked to a DNA-binding domain to form a nuclease. such as a zinc finger nuclease, a TALEN, or a CRISPR/Cas nuclease system. See, e.g., U.S. Pat. Nos. 7,951,925; 8,110,379 and 8,586,526; U.S. Publication Nos. 20080159996; 201000218264; 20120017290; 20110265198; 20130137104; 20130122591; 20130177983 and 20130177960 and U.S. Provisional Application No. 61/823,689 As noted above, the cleavage domain may be heterologous to the DNA-binding domain, for example a zinc finger DNA-binding domain and a cleavage domain from a nuclease or a TALEN DNA-binding domain and a cleavage domain, or meganuclease DNA-binding domain and cleavage domain from a different nuclease. Heterologous cleavage domains can be obtained from any endonuclease or exonuclease. Exemplary endonucleases from which a cleavage domain can be derived include, but are not limited to, restriction endonucleases and homing endonucleases. See, for example, 2002-2003 Catalogue, New England Biolabs, Beverly, Mass.; and Belfort et al. (1997) Nucleic Acids Res. 25:3379-3388. Additional enzymes which cleave DNA are known (e.g., Si Nuclease; mung bean nuclease; pancreatic DNase I; micrococcal nuclease; yeast HO endonuclease; see also Linn et al. (eds.) Nucleases, Cold Spring Harbor Laboratory Press, 1993). One or more of these enzymes (or functional fragments thereof) can be used as a source of cleavage domains and cleavage half-domains.
Similarly, a cleavage half-domain can be derived from any nuclease or portion thereof, as set forth above, that requires dimerization for cleavage activity. In general, two fusion proteins are required for cleavage if the fusion proteins comprise cleavage half-domains. Alternatively, a single protein comprising two cleavage half-domains can be used. The two cleavage half-domains can be derived from the same endonuclease (or functional fragments thereof), or each cleavage half-domain can be derived from a different endonuclease (or functional fragments thereof). In addition, the target sites for the two fusion proteins are preferably disposed, with respect to each other, such that binding of the two fusion proteins to their respective target sites places the cleavage half-domains in a spatial orientation to each other that allows the cleavage half-domains to form a functional cleavage domain, e.g., by dimerizing. Thus, in certain embodiments, the near edges of the target sites are separated by 5-8 nucleotides or by 15-18 nucleotides. However any number of nucleotides or nucleotide pairs can intervene between two target sites (e.g., from 2 to 50 nucleotide pairs or more). In general, the site of cleavage lies between the target sites.
Restriction endonucleases (restriction enzymes) are present in many species and are capable of sequence-specific binding to DNA (at a recognition site), and cleaving DNA at or near the site of binding. Certain restriction enzymes (e.g., Type IIS) cleave DNA at sites removed from the recognition site and have separable binding and cleavage domains. For example, the Type IIS enzyme Fok I catalyzes double-stranded cleavage of DNA, at 9 nucleotides from its recognition site on one strand and 13 nucleotides from its recognition site on the other. See, for example, U.S. Pat. Nos. 5,356,802; 5,436,150 and 5,487,994; as well as Li et al. (1992) Proc. Natl. Acad. Sci. USA 89:4275-4279; Li et al. (1993) Proc. Natl. Acad. Sci. USA 90:2764-2768; Kim et al. (1994a) Proc. Natl. Acad. Sci. USA 91:883-887; Kim et al. (1994b) J. Biol. Chem. 269:31,978-31,982. Thus, in one embodiment, fusion proteins comprise the cleavage domain (or cleavage half-domain) from at least one Type IIS restriction enzyme and one or more zinc finger binding domains, which may or may not be engineered.
An exemplary Type IIS restriction enzyme, whose cleavage domain is separable from the binding domain, is Fok I. This particular enzyme is active as a dimer. Bitinaite et al. (1998) Proc. Natl. Acad. Sci. USA 95: 10,570-10,575. Accordingly, for the purposes of the present disclosure, the portion of the Fok I enzyme used in the disclosed fusion proteins is considered a cleavage half-domain. Thus, for targeted double-stranded cleavage and/or targeted replacement of cellular sequences using zinc finger-Fok I fusions, two fusion proteins, each comprising a FokI cleavage half-domain, can be used to reconstitute a catalytically active cleavage domain. Alternatively, a single polypeptide molecule containing a DNA binding domain and two Fok I cleavage half-domains can also be used.
A cleavage domain or cleavage half-domain can be any portion of a protein that retains cleavage activity, or that retains the ability to multimerize (e.g., dimerize) to form a functional cleavage domain.
Exemplary Type IIS restriction enzymes are described in International Publication WO 07/014,275, incorporated herein in its entirety. Additional restriction enzymes also contain separable binding and cleavage domains, and these are contemplated by the present disclosure. See, for example, Roberts et al. (2003) Nucleic Acids Res. 31:418-420.
In certain embodiments, the cleavage domain comprises one or more engineered cleavage half-domain (also referred to as dimerization domain mutants) that minimize or prevent homodimerization, as described, for example, in U.S. Patent Publication Nos. 20050064474; 20060188987; 20080131962 and 20110201055, the disclosures of all of which are incorporated by reference in their entireties herein. Amino acid residues at positions 446, 447, 479, 483, 484, 486, 487, 490, 491, 496, 498, 499, 500, 531, 534, 537, and 538 of Fok I are all targets for influencing dimerization of the Fok I cleavage half-domains.
Exemplary engineered cleavage half-domains of Fok I that form obligate heterodimers include a pair in which a first cleavage half-domain includes mutations at amino acid residues at positions 490 and 538 of Fok I and a second cleavage half-domain includes mutations at amino acid residues 486 and 499.
Thus, in one embodiment, a mutation at 490 replaces Glu (E) with Lys (K); the mutation at 538 replaces Iso (I) with Lys (K); the mutation at 486 replaced Gln (Q) with Glu (E); and the mutation at position 499 replaces Iso (I) with Lys (K). Specifically, the engineered cleavage half-domains described herein were prepared by mutating positions 490 (E→K) and 538 (I→K) in one cleavage half-domain to produce an engineered cleavage half-domain designated “E490K:I538K” and by mutating positions 486 (Q→E) and 499 (I→L) in another cleavage half-domain to produce an engineered cleavage half-domain designated “Q486E:I499L”. The engineered cleavage half-domains described herein are obligate heterodimer mutants in which aberrant cleavage is minimized or abolished. See, e.g., U.S. Patent Publication No. 2008/0131962, the disclosure of which is incorporated by reference in its entirety for all purposes.
In certain embodiments, the engineered cleavage half-domain comprises mutations at positions 486, 499 and 496 (numbered relative to wild-type FokI), for instance mutations that replace the wild type Gln (Q) residue at position 486 with a Glu (E) residue, the wild type Iso (I) residue at position 499 with a Leu (L) residue and the wild-type Asn (N) residue at position 496 with an Asp (D) or Glu (E) residue (also referred to as a “ELD” and “ELE” domains, respectively). In other embodiments, the engineered cleavage half-domain comprises mutations at positions 490, 538 and 537 (numbered relative to wild-type FokI), for instance mutations that replace the wild type Glu (E) residue at position 490 with a Lys (K) residue, the wild type Iso (I) residue at position 538 with a Lys (K) residue, and the wild-type His (H) residue at position 537 with a Lys (K) residue or a Arg (R) residue (also referred to as “KKK” and “KKR” domains, respectively). In other embodiments, the engineered cleavage half-domain comprises mutations at positions 490 and 537 (numbered relative to wild-type FokI), for instance mutations that replace the wild type Glu (E) residue at position 490 with a Lys (K) residue and the wild-type His (H) residue at position 537 with a Lys (K) residue or a Arg (R) residue (also referred to as “KIK” and “KIR” domains, respectively). (See US Patent Publication No. 20110201055). Engineered cleavage half-domains described herein can be prepared using any suitable method, for example, by site-directed mutagenesis of wild-type cleavage half-domains (Fok I) as described in U.S. Patent Publication Nos. 20050064474; 20080131962 and 20110201055.
Alternatively, nucleases may be assembled in vivo at the nucleic acid target site using so-called “split-enzyme” technology (see e.g. U.S. Patent Publication No. 20090068164). Components of such split enzymes may be expressed either on separate expression constructs, or can be linked in one open reading frame where the individual components are separated, for example, by a self-cleaving 2A peptide or IRES sequence. Components may be individual zinc finger binding domains or domains of a meganuclease nucleic acid binding domain.
Nucleases can be screened for activity prior to use, for example in a yeast-based chromosomal system as described in WO 2009/042163 and 20090068164. Nuclease expression constructs can be readily designed using methods known in the art. See, e.g., United States Patent Publications 20030232410; 20050208489; 20050026157; 20050064474; 20060188987; 20060063231; and International Publication WO 07/014,275. Expression of the nuclease may be under the control of a constitutive promoter or an inducible promoter, for example the galactokinase promoter which is activated (de-repressed) in the presence of raffinose and/or galactose and repressed in presence of glucose.
In certain embodiments, the nuclease comprises a CRISPR/Cas system. The CRISPR (clustered regularly interspaced short palindromic repeats) locus, which encodes RNA components of the system, and the cas (CRISPR-associated) locus, which encodes proteins (Jansen et al., 2002. Mol. Microbiol. 43: 1565-1575; Makarova et al., 2002. Nucleic Acids Res. 30: 482-496; Makarova et al., 2006. Biol. Direct 1: 7; Haft et al., 2005. PLoS Comput. Biol. 1: e60) make up the gene sequences of the CRISPR/Cas nuclease system. CRISPR loci in microbial hosts contain a combination of CRISPR-associated (Cas) genes as well as non-coding RNA elements capable of programming the specificity of the CRISPR-mediated nucleic acid cleavage.
The Type II CRISPR is one of the most well characterized systems and carries out targeted DNA double-strand break in four sequential steps. First, two non-coding RNA, the pre-crRNA array and tracrRNA, are transcribed from the CRISPR locus. Second, tracrRNA hybridizes to the repeat regions of the pre-crRNA and mediates the processing of pre-crRNA into mature crRNAs containing individual spacer sequences. Third, the mature crRNA:tracrRNA complex directs Cas9 to the target DNA via Watson-Crick base-pairing between the spacer on the crRNA and the protospacer on the target DNA next to the protospacer adjacent motif (PAM), an additional requirement for target recognition. Finally, Cas9 mediates cleavage of target DNA to create a double-stranded break within the protospacer. Activity of the CRISPR/Cas system comprises of three steps: (i) insertion of alien DNA sequences into the CRISPR array to prevent future attacks, in a process called ‘adaptation’, (ii) expression of the relevant proteins, as well as expression and processing of the array, followed by (iii) RNA-mediated interference with the alien nucleic acid. Thus, in the bacterial cell, several of the so-called ‘Cas’ proteins are involved with the natural function of the CRISPR/Cas system and serve roles in functions such as insertion of the alien DNA etc.
In certain embodiments, Cas protein may be a “functional derivative” of a naturally occurring Cas protein. A “functional derivative” of a native sequence polypeptide is a compound having a qualitative biological property in common with a native sequence polypeptide. “Functional derivatives” include, but are not limited to, fragments of a native sequence and derivatives of a native sequence polypeptide and its fragments, provided that they have a biological activity in common with a corresponding native sequence polypeptide. A biological activity contemplated herein is the ability of the functional derivative to hydrolyze a DNA substrate into fragments. The term “derivative” encompasses both amino acid sequence variants of polypeptide, covalent modifications, and fusions thereof. Suitable derivatives of a Cas polypeptide or a fragment thereof include but are not limited to mutants, fusions, covalent modifications of Cas protein or a fragment thereof. Cas protein, which includes Cas protein or a fragment thereof, as well as derivatives of Cas protein or a fragment thereof, may be obtainable from a cell or synthesized chemically or by a combination of these two procedures. The cell may be a cell that naturally produces Cas protein, or a cell that naturally produces Cas protein and is genetically engineered to produce the endogenous Cas protein at a higher expression level or to produce a Cas protein from an exogenously introduced nucleic acid, which nucleic acid encodes a Cas that is same or different from the endogenous Cas. In some case, the cell does not naturally produce Cas protein and is genetically engineered to produce a Cas protein.
Exemplary CRISPR/Cas nuclease systems targeted to safe harbor and other genes are disclosed for example, in U.S. Provisional Application No. 61/823,689.
Thus, the nuclease comprises a DNA-binding domain in that specifically binds to a target site in any gene into which it is desired to insert a donor (transgene).
Target Sites
As described in detail above, DNA domains can be engineered to bind to any sequence of choice in a locus, for example a safe-harbor gene such as albumin. An engineered DNA-binding domain can have a novel binding specificity, compared to a naturally-occurring DNA-binding domain. Engineering methods include, but are not limited to, rational design and various types of selection. Rational design includes, for example, using databases comprising triplet (or quadruplet) nucleotide sequences and individual (e.g., zinc finger) amino acid sequences, in which each triplet or quadruplet nucleotide sequence is associated with one or more amino acid sequences of DNA binding domain which bind the particular triplet or quadruplet sequence. See, for example, co-owned U.S. Pat. Nos. 6,453,242 and 6,534,261, incorporated by reference herein in their entireties. Rational design of TAL-effector domains can also be performed. See, e.g., U.S. Pat. No. 8,586,526.
Exemplary selection methods applicable to DNA-binding domains, including phage display and two-hybrid systems, are disclosed in U.S. Pat. Nos. 5,789,538; 5,925,523; 6,007,988; 6,013,453; 6,410,248; 6,140,466; 6,200,759; and 6,242,568; as well as WO 98/37186; WO 98/53057; WO 00/27878; WO 01/88197 and GB 2,338,237.
Selection of target sites; nucleases and methods for design and construction of fusion proteins (and polynucleotides encoding same) are known to those of skill in the art and described in detail in U.S. Patent Application Publication Nos. 20050064474 and 20060188987, incorporated by reference in their entireties herein.
In addition, as disclosed in these and other references, DNA-binding domains (e.g., multi-finger zinc finger proteins) may be linked together using any suitable linker sequences, including for example, linkers of 5 or more amino acids. See, e.g., U.S. Pat. Nos. 6,479,626; 6,903,185; and 7,153,949 for exemplary linker sequences 6 or more amino acids in length. The proteins described herein may include any combination of suitable linkers between the individual DNA-binding domains of the protein. See, also, U.S. Pat. No. 8,586,526.
Donors
As noted above, insertion of an exogenous sequence (also called a “donor sequence” or “donor”), for example for correction of a mutant gene or for increased expression of a wild-type gene, particularly insertion of a functional version of at least one protein which is aberrantly expressed in a metabolic disorder.
Non-limiting examples of proteins that are aberrantly expressed in a metabolic disorder that may be encoded by the donors include MMAA, MMAB, MMACHC, MMADHC (C2orf25), MTRR, LMBRD1, MTR, propionyl-CoA carboxylase (PCC) (PCCA and/or PCCB subunits), a glucose-6-phosphate transporter (G6PT) protein or glucose-6-phosphatase (G6Pase), an LDL receptor (LDLR), an ApoB protein, an LDLRAP-1 protein, a PCSK9 protein, a mitochondrial protein such as NAGS (N-acetylglutamate synthetase), CPS1 (carbamoyl phosphate synthetase I), and OTC (ornithine transcarbamylase), ASS (argininosuccinic acid synthetase), ASL (argininosuccinase acid lyase) and/or ARG1 (arginase), and/or a solute carrier family 25 (SLC25A13, an aspartate/glutamate carrier) protein, a UGT1A1 or UDP glucuronsyltransferase polypeptide A1, a fumarylacetoacetate hydrolyase (FAH), an alanine-glyoxylate aminotransferase (AGXT) protein, a glyoxylate reductase/hydroxypyruvate reductase (GRHPR) protein, a transthyretin gene (TTR) protein, an ATP7B protein, a phenylalanine hydroxylase (PAH) protein and/or a lipoprotein lyase (LPL) protein.
A donor sequence can contain a non-homologous sequence flanked by two regions of homology to allow for efficient HDR at the location of interest. A donor molecule can contain several, discontinuous regions of homology to cellular chromatin. For example, for targeted insertion of sequences not normally present in a region of interest, said sequences can be present in a donor nucleic acid molecule and flanked by regions of homology to sequence in the region of interest.
Alternatively, donor sequences can be integrated via non-HDR mechanisms (e.g., NHEJ donor capture), in which case the donor polynucleotide (e.g., vector) need not containing sequences that are homologous to the region of interest in cellular chromatin.
The donor polynucleotide can be DNA or RNA, single-stranded or double-stranded and can be introduced into a cell in linear or circular (e.g., minicircle) form. See, e.g., U.S. Patent Publication Nos. 20100047805; 20110281361; and 20110207221. If introduced in linear form, the ends of the donor sequence can be protected (e.g., from exonucleolytic degradation) by methods known to those of skill in the art. For example, one or more dideoxynucleotide residues are added to the 3′ terminus of a linear molecule and/or self-complementary oligonucleotides are ligated to one or both ends. See, for example, Chang et al. (1987) Proc. Natl. Acad. Sci. USA 84:4959-4963; Nehls et al. (1996) Science 272:886-889. Additional methods for protecting exogenous polynucleotides from degradation include, but are not limited to, addition of terminal amino group(s) and the use of modified internucleotide linkages such as, for example, phosphorothioates, phosphoramidates, and O-methyl ribose or deoxyribose residues.
A polynucleotide can be introduced into a cell as part of a vector molecule having additional sequences such as, for example, replication origins, promoters and genes encoding antibiotic resistance. Moreover, donor polynucleotides can be introduced as naked nucleic acid, as nucleic acid complexed with an agent such as a liposome or poloxamer, or can be delivered by viruses (e.g., adenovirus, AAV, herpesvirus, retrovirus, lentivirus and integrase defective lentivirus (IDLV)).
The donor is generally inserted so that its expression is driven by the endogenous promoter at the integration site, namely the promoter that drives expression of the albumin gene. However, it will be apparent that the donor may comprise a promoter and/or enhancer, for example a constitutive promoter or an inducible or tissue specific promoter.
The donor molecule may be inserted into an endogenous gene such that all, some or none of the endogenous gene is expressed. For example, a transgene as described herein may be inserted into a safe harbor locus such that some or none of the endogenous sequences are expressed, for example as a fusion with the transgene. In some embodiments, the endogenous sequences are albumin sequences. In other embodiments, the transgene (e.g., with or without albumin encoding sequences) is integrated into another (non-albumin) locus but encodes albumin sequences.
When albumin sequences (endogenous or part of the transgene) are expressed with the transgene, the albumin sequences may be full-length sequences (wild-type or mutant) or partial sequences. Preferably the albumin sequences are functional. Non-limiting examples of the function of these full length or partial albumin sequences include increasing the serum half-life of the polypeptide expressed by the transgene (e.g., therapeutic gene) and/or acting as a carrier.
Furthermore, although not required for expression, exogenous sequences may also include transcriptional or translational regulatory sequences, for example, promoters, enhancers, insulators, internal ribosome entry sites, sequences encoding 2A peptides and/or polyadenylation signals.
Delivery
The nucleases, polynucleotides encoding these nucleases, donor polynucleotides and compositions comprising the proteins and/or polynucleotides described herein may be delivered in vivo or ex vivo by any suitable means.
Methods of delivering nucleases as described herein are described, for example, in U.S. Pat. Nos. 6,453,242; 6,503,717; 6,534,261; 6,599,692; 6,607,882; 6,689,558; 6,824,978; 6,933,113; 6,979,539; 7,013,219; and 7,163,824, the disclosures of all of which are incorporated by reference herein in their entireties.
Nucleases and/or donor constructs as described herein may also be delivered using vectors containing sequences encoding one or more of the zinc finger or TALEN protein(s). Any vector systems may be used including, but not limited to, plasmid vectors, retroviral vectors, lentiviral vectors, adenovirus vectors, poxvirus vectors; herpesvirus vectors and adeno-associated virus vectors, etc. See, also, U.S. Pat. Nos. 6,534,261; 6,607,882; 6,824,978; 6,933,113; 6,979,539; 7,013,219; and 7,163,824, incorporated by reference herein in their entireties. Furthermore, it will be apparent that any of these vectors may comprise one or more of the sequences needed for treatment. Thus, when one or more nucleases and a donor construct are introduced into the cell, the nucleases and/or donor polynucleotide may be carried on the same vector or on different vectors. When multiple vectors are used, each vector may comprise a sequence encoding one or multiple nucleases and/or donor constructs.
Conventional viral and non-viral based gene transfer methods can be used to introduce nucleic acids encoding nucleases and donor constructs in cells (e.g., mammalian cells) and target tissues. Non-viral vector delivery systems include DNA plasmids, naked nucleic acid, and nucleic acid complexed with a delivery vehicle such as a liposome or poloxamer. Viral vector delivery systems include DNA and RNA viruses, which have either episomal or integrated genomes after delivery to the cell. For a review of gene therapy procedures, see Anderson, Science 256:808-813 (1992); Nabel & Feigner, TIBTECH 11:211-217 (1993); Mitani & Caskey, TIBTECH 11:162-166 (1993); Dillon, TIBTECH 11:167-175 (1993); Miller, Nature 357:455-460 (1992); Van Brunt, Biotechnology 6(10):1149-1154 (1988); Vigne, Restorative Neurology and Neuroscience 8:35-36 (1995); Kremer & Perricaudet, British Medical Bulletin 51(1):31-44 (1995); Haddada et al., in Current Topics in Microbiology and Immunology Doerfler and Böhm (eds.) (1995); and Yu et al., Gene Therapy 1:13-26 (1994).
Methods of non-viral delivery of nucleic acids include electroporation, lipofection, microinjection, biolistics, virosomes, liposomes, immunoliposomes, polycation or lipid:nucleic acid conjugates, naked DNA, artificial virions, and agent-enhanced uptake of DNA. Sonoporation using, e.g., the Sonitron 2000 system (Rich-Mar) can also be used for delivery of nucleic acids.
Additional exemplary nucleic acid delivery systems include those provided by Amaxa Biosystems (Cologne, Germany), Maxcyte, Inc. (Rockville, Md.), BTX Molecular Delivery Systems (Holliston, Mass.) and Copernicus Therapeutics Inc, (see for example U.S. Pat. No. 6,008,336). Lipofection is described in e.g., U.S. Pat. Nos. 5,049,386; 4,946,787; and 4,897,355) and lipofection reagents are sold commercially (e.g., TransfectamTM and LipofectinTM). Cationic and neutral lipids that are suitable for efficient receptor-recognition lipofection of polynucleotides include those of Feigner, WO 91/17424, WO 91/16024.
The preparation of lipid:nucleic acid complexes, including targeted liposomes such as immunolipid complexes, is well known to one of skill in the art (see, e.g., Crystal, Science 270:404-410 (1995); Blaese et al., Cancer Gene Ther. 2:291-297 (1995); Behr et al., Bioconjugate Chem. 5:382-389 (1994); Remy et al., Bioconjugate Chem. 5:647-654 (1994); Gao et al., Gene Therapy 2:710-722 (1995); Ahmad et al., Cancer Res. 52:4817-4820 (1992); U.S. Pat. Nos. 4,186,183, 4,217,344, 4,235,871, 4,261,975, 4,485,054, 4,501,728, 4,774,085, 4,837,028, and 4,946,787).
Additional methods of delivery include the use of packaging the nucleic acids to be delivered into EnGeneIC delivery vehicles (EDVs). These EDVs are specifically delivered to target tissues using bispecific antibodies where one arm of the antibody has specificity for the target tissue and the other has specificity for the EDV. The antibody brings the EDVs to the target cell surface and then the EDV is brought into the cell by endocytosis. Once in the cell, the contents are released (see MacDiarmid et at (2009) Nature Biotechnology 27(7):643).
The use of RNA or DNA viral based systems for the delivery of nucleic acids encoding engineered ZFPs take advantage of highly evolved processes for targeting a virus to specific cells in the body and trafficking the viral payload to the nucleus. Viral vectors can be administered directly to patients (in vivo) or they can be used to treat cells in vitro and the modified cells are administered to patients (ex vivo). Conventional viral based systems for the delivery of ZFPs include, but are not limited to, retroviral, lentivirus, adenoviral, adeno-associated, vaccinia and herpes simplex virus vectors for gene transfer. Integration in the host genome is possible with the retrovirus, lentivirus, and adeno-associated virus gene transfer methods, often resulting in long term expression of the inserted transgene. Additionally, high transduction efficiencies have been observed in many different cell types and target tissues.
The tropism of a retrovirus can be altered by incorporating foreign envelope proteins, expanding the potential target population of target cells. Lentiviral vectors are retroviral vectors that are able to transduce or infect non-dividing cells and typically produce high viral titers. Selection of a retroviral gene transfer system depends on the target tissue. Retroviral vectors are comprised of cis-acting long terminal repeats with packaging capacity for up to 6-10 kb of foreign sequence. The minimum cis-acting LTRs are sufficient for replication and packaging of the vectors, which are then used to integrate the therapeutic gene into the target cell to provide permanent transgene expression. Widely used retroviral vectors include those based upon murine leukemia virus (MuLV), gibbon ape leukemia virus (GaLV), Simian Immunodeficiency virus (SIV), human immunodeficiency virus (HIV), and combinations thereof (see, e.g., Buchscher et al., J. Virol. 66:2731-2739 (1992); Johann et al., J. Virol. 66:1635-1640 (1992); Sommerfelt et al., Virol. 176:58-59 (1990); Wilson et al., J. Virol. 63:2374-2378 (1989); Miller et al., J. Virol. 65:2220-2224 (1991); PCT/US94/05700).
In applications in which transient expression is preferred, adenoviral based systems can be used. Adenoviral based vectors are capable of very high transduction efficiency in many cell types and do not require cell division. With such vectors, high titer and high levels of expression have been obtained. This vector can be produced in large quantities in a relatively simple system. Adeno-associated virus (“AAV”) vectors are also used to transduce cells with target nucleic acids, e.g., in the in vitro production of nucleic acids and peptides, and for in vivo and ex vivo gene therapy procedures (see, e.g., West et al., Virology 160:38-47 (1987); U.S. Pat. No. 4,797,368; WO 93/24641; Kotin, Human Gene Therapy 5:793-801 (1994); Muzyczka, J. Clin. Invest. 94:1351 (1994). Construction of recombinant AAV vectors is described in a number of publications, including U.S. Pat. No. 5,173,414; Tratschin et al., Mol. Cell. Biol. 5:3251-3260 (1985); Tratschin, et al., Mol. Cell. Biol. 4:2072-2081 (1984); Hermonat & Muzyczka, PNAS 81:6466-6470 (1984); and Samulski et al., J. Virol. 63:03822-3828 (1989).
At least six viral vector approaches are currently available for gene transfer in clinical trials, which utilize approaches that involve complementation of defective vectors by genes inserted into helper cell lines to generate the transducing agent.
pLASN and MFG-S are examples of retroviral vectors that have been used in clinical trials (Dunbar et al., Blood 85:3048-305 (1995); Kohn et al., Nat. Med. 1:1017-102 (1995); Malech et al., PNAS 94:22 12133-12138 (1997)). PA317/pLASN was the first therapeutic vector used in a gene therapy trial. (Blaese et al., Science 270:475-480 (1995)). Transduction efficiencies of 50% or greater have been observed for MFG-S packaged vectors. (Ellem et al., Immunol Immunother. 44(1):10-20 (1997); Dranoff et al., Hum. Gene Ther. 1:111-2 (1997).
Recombinant adeno-associated virus vectors (rAAV) are a promising alternative gene delivery systems based on the defective and nonpathogenic parvovirus adeno-associated type 2 virus. All vectors are derived from a plasmid that retains only the AAV 145 bp inverted terminal repeats flanking the transgene expression cassette. Efficient gene transfer and stable transgene delivery due to integration into the genomes of the transduced cell are key features for this vector system. (Wagner et al., Lancet 351:9117 1702-3 (1998), Kearns et al., Gene Ther. 9:748-55 (1996)). Other AAV serotypes, including AAV1, AAV3, AAV4, AAV5, AAV6, AAV8, AAV 8.2, AAV9, AAV rh10 and pseudotyped AAV such as AAV2/8, AAV2/5 and AAV2/6 can also be used in accordance with the present invention.
Replication-deficient recombinant adenoviral vectors (Ad) can be produced at high titer and readily infect a number of different cell types. Most adenovirus vectors are engineered such that a transgene replaces the Ad E1a, E1b, and/or E3 genes; subsequently the replication defective vector is propagated in human 293 cells that supply deleted gene function in trans. Ad vectors can transduce multiple types of tissues in vivo, including non-dividing, differentiated cells such as those found in liver, kidney and muscle. Conventional Ad vectors have a large carrying capacity. An example of the use of an Ad vector in a clinical trial involved polynucleotide therapy for anti-tumor immunization with intramuscular injection (Sterman et al., Hum. Gene Ther. 7:1083-9 (1998)). Additional examples of the use of adenovirus vectors for gene transfer in clinical trials include Rosenecker et al., Infection 24:1 5-10 (1996); Sterman et al., Hum. Gene Ther. 9:7 1083-1089 (1998); Welsh et al., Hum. Gene Ther. 2:205-18 (1995); Alvarez et al., Hum. Gene Ther. 5:597-613 (1997); Topf et al., Gene Ther. 5:507-513 (1998); Sterman et al., Hum. Gene Ther. 7:1083-1089 (1998).
Packaging cells are used to form virus particles that are capable of infecting a host cell. Such cells include 293 cells, which package adenovirus, and ψ2 cells or PA317 cells, which package retrovirus. Viral vectors used in gene therapy are usually generated by a producer cell line that packages a nucleic acid vector into a viral particle. The vectors typically contain the minimal viral sequences required for packaging and subsequent integration into a host (if applicable), other viral sequences being replaced by an expression cassette encoding the protein to be expressed. The missing viral functions are supplied in trans by the packaging cell line. For example, AAV vectors used in gene therapy typically only possess inverted terminal repeat (ITR) sequences from the AAV genome which are required for packaging and integration into the host genome. Viral DNA is packaged in a cell line, which contains a helper plasmid encoding the other AAV genes, namely rep and cap, but lacking ITR sequences. The cell line is also infected with adenovirus as a helper. The helper virus promotes replication of the AAV vector and expression of AAV genes from the helper plasmid. The helper plasmid is not packaged in significant amounts due to a lack of ITR sequences. Contamination with adenovirus can be reduced by, e.g., heat treatment to which adenovirus is more sensitive than AAV.
In many gene therapy applications, it is desirable that the gene therapy vector be delivered with a high degree of specificity to a particular tissue type. Accordingly, a viral vector can be modified to have specificity for a given cell type by expressing a ligand as a fusion protein with a viral coat protein on the outer surface of the virus. The ligand is chosen to have affinity for a receptor known to be present on the cell type of interest. For example, Han et al., Proc. Natl. Acad. Sci. USA 92:9747-9751 (1995), reported that Moloney murine leukemia virus can be modified to express human heregulin fused to gp70, and the recombinant virus infects certain human breast cancer cells expressing human epidermal growth factor receptor. This principle can be extended to other virus-target cell pairs, in which the target cell expresses a receptor and the virus expresses a fusion protein comprising a ligand for the cell-surface receptor. For example, filamentous phage can be engineered to display antibody fragments (e.g., FAB or Fv) having specific binding affinity for virtually any chosen cellular receptor. Although the above description applies primarily to viral vectors, the same principles can be applied to nonviral vectors. Such vectors can be engineered to contain specific uptake sequences which favor uptake by specific target cells.
Gene therapy vectors can be delivered in vivo by administration to an individual patient, typically by systemic administration (e.g., intravenous, intraperitoneal, intramuscular, subdermal, or intracranial infusion) or topical application, as described below. Alternatively, vectors can be delivered to cells ex vivo, such as cells explanted from an individual patient (e.g., lymphocytes, bone marrow aspirates, tissue biopsy) or universal donor hematopoietic stem cells, followed by reimplantation of the cells into a patient, usually after selection for cells which have incorporated the vector.
Vectors (e.g., retroviruses, adenoviruses, liposomes, etc.) containing nucleases and/or donor constructs can also be administered directly to an organism for transduction of cells in vivo. Alternatively, naked DNA can be administered. Administration is by any of the routes normally used for introducing a molecule into ultimate contact with blood or tissue cells including, but not limited to, injection, infusion, topical application and electroporation. Suitable methods of administering such nucleic acids are available and well known to those of skill in the art, and, although more than one route can be used to administer a particular composition, a particular route can often provide a more immediate and more effective reaction than another route.
Vectors suitable for introduction of polynucleotides described herein include non-integrating lentivirus vectors (IDLV). See, for example, Ory et al. (1996) Proc. Natl. Acad. Sci. USA 93:11382-11388; Dull et al. (1998) J. Virol. 72:8463-8471; Zuffery et al. (1998) J. Virol. 72:9873-9880; Follenzi et al. (2000) Nature Genetics 25:217-222; U.S. Patent Publication No 2009/054985.
Pharmaceutically acceptable carriers are determined in part by the particular composition being administered, as well as by the particular method used to administer the composition. Accordingly, there is a wide variety of suitable formulations of pharmaceutical compositions available, as described below (see, e.g., Remington's Pharmaceutical Sciences, 17th ed., 1989).
It will be apparent that the nuclease-encoding sequences and donor constructs can be delivered using the same or different systems. For example, a donor polynucleotide can be carried by a plasmid, while the one or more nucleases can be carried by an AAV vector. Furthermore, the different vectors can be administered by the same or different routes (intramuscular injection, tail vein injection, other intravenous injection, intraperitoneal administration and/or intramuscular injection. The vectors can be delivered simultaneously or in any sequential order.
Formulations for both ex vivo and in vivo administrations include suspensions in liquid or emulsified liquids. The active ingredients often are mixed with excipients which are pharmaceutically acceptable and compatible with the active ingredient. Suitable excipients include, for example, water, saline, dextrose, glycerol, ethanol or the like, and combinations thereof. In addition, the composition may contain minor amounts of auxiliary substances, such as, wetting or emulsifying agents, pH buffering agents, stabilizing agents or other reagents that enhance the effectiveness of the pharmaceutical composition.
Applications
The methods and compositions of the invention can be used in any circumstance wherein it is desired to supply a transgene encoding one or more proteins that are aberrantly expressed in a subject with a metabolic disorder (e.g., methylmalonic acidemia, propionic acidemia, glycogen storage diseases type 1, familial hypercholesterolemia (FH) is a common genetic and metabolic disease, urea cycle disorders (e.g., citrullinemia or OTC deficiency), Crigler Najjar Syndrome (CNS), Gilbert syndrome, hepatorenal tyrosinemia, primary hyperoxaluria. transthyretin gene (TTR)-mediated amyloidosis (ATTR), Wilson's disease, phenylketonuria (PKU), and familial lipoprotein lipase deficiency (LPLD). The transgene can express one or more of following proteins to supply functional proteins lacking in the subject: MMAA, MMAB, MMACHC, MMADHC (C2orf25), MTRR, LMBRD1, MTR, propionyl-CoA carboxylase (PCC) (PCCA and/or PCCB subunits), a glucose-6-phosphate transporter (G6PT) protein or glucose-6-phosphatase (G6Pase), an LDL receptor (LDLR), an ApoB protein, an LDLRAP-1 protein, a PCSK9 protein, a mitochondrial protein such as NAGS (N-acetylglutamate synthetase), CPS1 (carbamoyl phosphate synthetase I), and OTC (ornithine transcarbamylase), ASS (argininosuccinic acid synthetase), ASL (argininosuccinase acid lyase) and/or ARG1 (arginase), and/or a solute carrier family 25 (SLC25A13, an aspartate/glutamate carrier) protein, a UGT1A1 or UDP glucuronsyltransferase polypeptide A1, a fumarylacetoacetate hydrolyase (FAH), an alanine-glyoxylate aminotransferase (AGXT) protein, a glyoxylate reductase/hydroxypyruvate reductase (GRHPR) protein, a transthyretin gene (TTR) protein, an ATP7B protein, a phenylalanine hydroxylase (PAH) protein and/or a lipoprotein lyase (LPL) protein.
Thus, this technology is of use in conditions where a subject is deficient in some protein or RNA involved in a metabolic disorder. Metabolic diseases are those in which a protein or RNA in a metabolic pathway is dysfunctional in some manner such that the pathway does not function properly. Thus, the patient suffers due to either a build-up of an altered protein or RNA, from the build-up of an intermediate in the pathway, or from the lack of the final product of the pathway, or from all of the above.
Methylmalonic acidemia is an autosomal recessive metabolic disease that is lethal early in life (prevalence of approximately 1/25,000 births) where the defect is in the conversion of methylmalonyl-coenzyme A (coA) into succinyl-CoA by methylmalonyl CoA mutase. There are several types of methylmalonic acidemia that are classified by which protein in the pathway is encoded by the mutated or poorly expressed gene sequence. It appears the conversion of vitamin B12 into its co-enzyme complexes is defective. Several enzymes are required for this process, and mutations in the genes encoding these enzymes appear to be the cause of the complementation groups observed (cb1A through cb1H, see Dobson et al (2002) Proc Nat Acad Sci USA 99(24): 15554-15559). The complementation groups and genes associated are shown below in Table A.







TABLE A







Genes and complementation groups associated


with Methylmalonic acidemia










Complementation Group
Gene Symbol







cblA
MMAA



cblB
MMAB



cblC
MMACHC



cblD
MMADHC



cblD (variant 1)
(C2orf25)



cblD (variant 2)



cblE
MTRR



cblF
LMBRD1



cblG
MTR










Thus, insertion of a gene encoding a wild-type allele of a defective gene that is causing methylmalonic acidemia into an albumin locus may provide a therapeutic benefit for these patients.
Propionic acidemia is a disorder of branch-chain amino acid metabolism characterized by the build-up of propionic acid resulting in episodes of vomiting, dehydration and severe metabolic acidosis (prevalence of approximately 1/35,000 births, but closer to 1/3000 in Saudi Arabia). Normally, carboxylation of propionyl-CoA is a two-step reaction where in the first step, bicarbonate is attached to the ureido nitrogen of the apoenzyme-biotin complex, forming a carboxybiotin-apoenzyme intermediate. This complex, in turn, reacts with propionyl-CoA and transfers the carboxyl group from biotin to the second carbon of propionyl-CoA, forming D-methylmalonyl-CoA. Both of these steps are catalyzed by propionyl-CoA carboxylase (PCC), a mitochondrial protein made of pairs of non-identical α and β subunits, encoded by the PCCA and PCCB genes, respectively. Mutation in either of these genes can lead to propionic acidemia. Using the methods and compositions disclosed in this invention, wild-type copies of PCCA and/or PCCB gene could be inserted, with the optional inclusion of a mitochondrial targeting peptide, into the albumin locus in the liver such that functional PCC could be made, preventing the build-up of proprionic acid.
Glycogen storage diseases type 1 are caused by a deficiency in the glucose-6-phosphate alpha system, a complex that is important in maintaining blood glucose levels (prevalence of about 1/50,000 births in the United States). The complex consists of a glucose-6-phosphate transporter (G6PT) that translocates glucose-6-phosphate from the cytoplasm into the lumen of the endoplasmic reticulum, and a G6Pase-α catalytic unit that hydrolyses the glucose-6-phosphate into glucose and phosphate. A deficiency in G6Pase-α causes GSD type Ia (GSD-Ia) and a deficiency in G6PT causes GSD type Ib (GSD-Ib). Both GSD-Ia and GSD-Ib patients manifest a disturbed glucose homeostasis, while GSD-Ib patients also suffer symptoms of neutropenia and myeloid dysfunctions. Both enzymes are transmembrane proteins associated with the endoplasmic reticulum. Current treatments treat the symptoms to some extent, but are not curative. There are animal models of these diseases and attempts have been made using these models to correct the disease via gene therapy. Wild type genes were delivered to the animals using AAV vectors. While some benefit was seen, problems relating to AAV tropism, and lack of sufficient expression of the transgene remained (see Chou and Mansfield (2007) Curr Gene Ther 7(2): 79). Thus, using the methods and compositions of the current invention, a transgene containing the appropriate gene related to the glucose-6-phosphate alpha system can be introduced into the liver and expressed via or at an albumin locus (e.g., from endogenous albumin control elements and/or exogenous promoters).
Familial hypercholesterolemia (FH) is a common genetic and metabolic disease. Most of the patients have a defect in the LDL receptor (LDLR) gene (1/500 births), while others have detects in ApoB (1/1000), PCSK9 (<1/2500), or LDLRAP-1. The LDLR gene mutations fall into 5 activity classes: Class I—no synthesis of LDLR; Class II—LDLR complex is not transported to the golgi apparatus; Class III—LDLR does not bind to LDL; Class IV—LDLR:LDL complex does not cluster properly in the cell membrane; and Class V—LDLR does not recycle properly in the cell. Expression of a wild type LDLR gene from an albumin locus could circumvent all these class of LDLR mutations. ApoB is a protein that is part of the lipoprotein particle and FH is associated with the R3500Q mutation. Expression of a transgene encoding wild-type equivalents of these genes could significantly impact the clinical manifestations of FH. Additionally, the methods and compositions of the invention contemplate the expression of a transcriptional regulator from an albumin locus (e.g. a ZFP-TF) that would specifically increase the expression of a gene if the mutation caused decreased expression.
Another class of metabolic genetic diseases are those involved in the urea cycle. These occur with a prevalence rate of 1/30,000 births and involve several genes. One of the more well-known urea cycle disorders is called Citrullinemia (associated with mutations in the ASS1 or SLC25A13 genes). Another well-known example is OTC deficiency, cause by a low level expression of ornithine transcarbamoylase. Some of these genes that are linked to urea cycle disorders encode proteins that are located in the mitochondria while others encode cytosolic proteins. The mitochondrial proteins are encoded by the NAGS (N-acetylglutamate synthetase), CPS1 (carbamoyl phosphate synthetase I), and OTC (ornithine transcarbamylase) genes while the cytosolic proteins are encoded by ASS (argininosuccinic acid synthetase), ASL (argininosuccinase acid lyase) and ARG1 (arginase) genes. The SLC25A13 gene also encodes solute carrier family 25 (aspartate/glutamate carrier), member 13 which is involved making citrin, which is needed to transport important urea cycle solutes into the mitochondria. The urea cycle takes place in the liver and serves to place ammonia in the less toxic form of urea or uric acid. Targeted integration at an albumin locus in the liver of a wild-type version of a gene encoding one of these enzymes could be used to treat these disorders.
A very rare genetic metabolic disorder is Crigler Najjar Syndrome (CNS, incidence of about 1/1,000,000 births) and related Gilbert syndrome are both disorders affecting the metabolism of billirubin. This disorder can be caused by mutations in the UGT1A1 (or UDP glucuronsyltransferase polypeptide A1) where type 1 CNS is characterized by a complete lack of UGT1A1 and type II CNS has low level expression. The biochemical role of the UGT1A1 protein is to degrade the lyophillic bilirubin into water soluble compounds for excretion. Lack of UGT1A1 activity can lead to hyperbillirubinemia and current treatment involves hours of time spent under ultra-violet irridation to cause billirubin breakdown through the skin. Expression of a wild-type or functionally similar UGT1A1 gene from the albumin locus in the liver via the compositions and methods of the invention could alleviate these conditions.
Hepatorenal tyrosinemia, also called Type 1 tyrosinemia is another genetic metabolic disease and is caused by lack of fumarylacetoacetate hydrolyase activity (encoded by FAH), resulting in the accumulation of fumarylacetoacetate in hepatocytes and proximal renal tubule cells causing oxidative damage and DNA damage, and eventually cell death. The incidence of Type 1 tyrosinemia is approximately 1/100,000 worldwide, but in Quebec, the incidence is about 1/16,000. It is the last enzyme in the tyrosine catabolism pathway, and treatment of this disease using the methods and compositions of this invention could be achieved by expression of a wild-type version of FAH at an albumin locus.
Mutations in the AGXT gene (alanine-glyoxylate aminotransferase) can cause another metabolic disease known as Primary Hyperoxaluria. Incidence of this disease is approximately 3/1,000,000 but is more common in the Mediterranean regions. Type I is primarily caused by mutations in AGXT (50 mutations have been identified) while type II is caused by mutations in glyoxylate reductase/hydroxypyruvate reductase (GRHPR). The breakdown and processing of certain sugars and amino acids produces glyoxylate which is converted to glycine or glycolate through the action of AGXT and GRHPR. A shortage of these enzymes, prevents the conversion of glyoxylate to glycine or glycolate, and then the glyoxylate gets converted to oxalate. Patients develop a build-up of oxalate, leading to kidney damage and injury to other organs. Patients also develop severe kidney stones. Expression of a wild type version of the defective copy of either of these genes as appropriate from an albumin locus could be therapeutic for these patients.
A genetic disease caused by mutations in the transthyretin gene (TTR) can lead to the TTR mediated amyloidosis (ATTR) and has an incidence of about 1/100,000. TTR is a protein found in serum and cerebrospinal fluid that carries the thyroid hormone thyroxine (T4). Misfolding of this protein is associated with amyloid diseases and over 100 mutations in the gene sequence have been described that can increase the susceptibility of the protein to misfolding. Expression of a wild-type version of the gene from an albumin locus combined with a knock-out of the mutant form of the gene could lead to effective treatment of the disease.
Wilson's disease or hepatolenticular degeneration is an autosomal recessive genetic disorder (incidence of 1/30,000) in which copper accumulates in tissues; this manifests as neurological or psychiatric symptoms and liver disease. It is caused by mutations in the Wilson disease n (ATP7B) gene which encodes a P-type ATPase that transports copper into bile and incorporates it into ceruloplasmin. Excess build up of copper caused by a defective ATP7B gene can be fatal, but expression of a wild-type version of the protein can be effective. Thus, expression of ATP7B via an albumin locus could be helpful for patients afflicted with this disease.
Phenylketonuria (PKU) is an autosomal recessive metabolic genetic disorder characterized by a mutation in the gene encoding the hepatic enzyme phenylalanine hydroxylase (PAH), rendering it nonfunctional or hypomorphic. This enzyme is necessary to metabolize phenylalanine to tyrosine. Build up of phenylalanine can lead to seizures, mental retardation and other medical problems. The treatment for this disorder to follow a strict diet avoiding foods containing aromatic amino acids, sometimes for life. Incidence is approximately 1/15,000 in the United States. Use of the methods and compositions of the invention could lead to expression of a wild-type PAH from an albumin locus in the liver, leading to a reduction of phenylalanine concentration.
Another inherited metabolic disorder is familial lipoprotein lipase deficiency (LPLD). This disorder is caused be a defective LPL or lipoprotein lyase gene, and is associated with a disruption of the normal breakdown of fats in the body. The condition is characterized by pancreatitis, abdominal pain, enlargement of the liver and hepatosplenomegaly. LPL is important for the breakdown of lipoproteins from chylomicrons and very low density lipoproteins. More than 200 mutations in LPL have been characterized but the most common is G188E. These mutations reduce or remove all lipoprotein lipase activity. Thus, expression of a wild-type version of the LPL gene from an albumin locus in the liver could be used to treat these patients.
The following Examples relate to exemplary embodiments of the present disclosure in which the nuclease comprises a zinc finger nuclease (ZFN), TALEN or CRISPR/Cas system. It will be appreciated that this is for purposes of exemplification only and that other nucleases can be used, for instance homing endonucleases (meganucleases) with engineered DNA-binding domains and/or fusions of naturally occurring of engineered homing endonucleases (meganucleases) DNA-binding domains and heterologous cleavage domains.
EXAMPLES
Example 1
Targeted Integration of a Transgene to Cells
A safe harbor locus in a target cell (e.g., CD34+ hematopoietic stem cell) is targeted for addition of a transgene encoding one or more proteins that are aberrantly expressed in a metabolic disorder. The safe harbor locus is CCR5, HPRT, AAVS1, Rosa or albumin and is targeted by one or more ZFNs, TALENs and/or CRISPR/Cas system as described in U.S. Pat. Nos. 7,951,925 and 8,110,379; U.S. Publication Nos. 20080159996; 201000218264; 20120017290; 20110265198; 20130137104; 20130122591; 20130177983 and 20130177960 and U.S. Provisional Application No. 61/823,689.
The metabolic disorder is methylmalonic acidemia, propionic acidemia, glycogen storage diseases type 1, familial hypercholesterolemia (FH) is a common genetic and metabolic disease, urea cycle disorders (e.g., citrullinemia OTC deficiency), Crigler Najjar Syndrome (CNS), Gilbert syndrome, hepatorenal tyrosinemia, primary hyperoxaluria. transthyretin gene (TTR)-mediated amyloidosis (ATTR), Wilson's disease, phenylketonuria (PKU), or familial lipoprotein lipase deficiency (LPLD). The protein is MMAA, MMAB, MMACHC, MMADHC (C2orf25), MTRR, LMBRD1, MTR, propionyl-CoA carboxylase (PCC) (PCCA and/or PCCB subunits), a glucose-6-phosphate transporter (G6PT) protein or glucose-6-phosphatase (G6Pase), an LDL receptor (LDLR), an ApoB protein, an LDLRAP-1 protein, a PCSK9 protein, a mitochondrial protein such as NAGS (N-acetylglutamate synthetase), CPS1 (carbamoyl phosphate synthetase I), and OTC (ornithine transcarbamylase), ASS (argininosuccinic acid synthetase), ASL (argininosuccinase acid lyase) and/or ARG1 (arginase), and/or a solute carrier family 25 (SLC25A13, an aspartate/glutamate carrier) protein, a UGT1A1 or UDP glucuronsyltransferase polypeptide A1, a fumarylacetoacetate hydrolyase (FAH), an alanine-glyoxylate aminotransferase (AGXT) protein, a glyoxylate reductase/hydroxypyruvate reductase (GRHPR) protein, a transthyretin gene (TTR) protein, an ATP7B protein, a phenylalanine hydroxylase (PAH) protein and/or a lipoprotein lyase (LPL) protein.
A vector (e.g., non-integrating chimeric adenoviral vector (Ad5/F35)) for the transient expression of safe-harbor targeted nucleases and a vector (e.g., integrase defective lentiviral vector (IDLV)) carrying the transgene of choice are constructed, essentially as described in U.S. Pat. Nos. 7,951,925 and 8,110,379; U.S. Publication Nos. 20080159996; 201000218264; 20120017290; 20110265198; 20130137104; 20130122591; 20130177983 and 20130177960 and U.S. Provisional Application No. 61/823,689. The transgene vector may include homology arms to the endogenous safe harbor locus for HDR integration or may be integrated via non-HDR mechanisms such as donor capture. Alternatively, the safe-harbor targeted nucleases are delivered to the cell as mRNAs.
Targeted gene addition is determined by any suitable means, for example by immuno-cytochemistry for the transgene protein 1-4 weeks post-transduction. In addition, appropriate PCR using specific primers recognizing the 5′ integration junction are used to confirm targeted integration into the safe harbor gene and/or by Surveyor nuclease Cel-1 assay at selected off-target loci.
Optionally, to increase the percentage of cells with integrated transgene, a drug resistance gene is also integrated in a site-specific manner into the safe harbor locus of the cells with the transgene.
Cells are also tested for toxicity of the transgene and/or nuclease and it is confirmed that nuclease-mediated gene addition does not interfere with transgene expression and/or growth of the cells in culture.
Example 2
Engraftment of Gene Targeted Cells into Subjects
To further assess the potential for gene-targeted cells to serve as a potential cell therapy, their capacity to express the transgene in vivo by administering the modified cells to mice or non-human primates. Nuclease-modified cells continue to express the transgene in vivo.
Example 3
In Vivo Targeted Integration
Subjects (e.g., mice or non-human primates) are administered vectors encoding a protein aberrantly expressed in a metabolic disorder and vectors encoding ZFN pairs targeting the albumin locus (as described in U.S. Patent Publication 20130177983) by intravenous injection (e.g., tail vein) as described in U.S. Patent Publication No. 20120128635.
Plasma levels of the donor protein are evaluated using standard techniques and show the protein is expressed in vivo.
All patents, patent applications and publications mentioned herein are hereby incorporated by reference in their entirety.
Although disclosure has been provided in some detail by way of illustration and example for the purposes of clarity of understanding, it will be apparent to those skilled in the art that various changes and modifications can be practiced without departing from the spirit or scope of the disclosure. Accordingly, the foregoing descriptions and examples should not be construed as limiting.

## Claims

1. An isolated mouse or human cell comprising an exogenous transgene encoding a protein, wherein the exogenous transgene is integrated site-specifically using a nuclease into an endogenous albumin gene, wherein the protein is a functional version of a protein selected from the group consisting of a methylmalonic aciduria CbIA Type (MMAA) protein, a methylmalonic aciduria CbIB Type (MMAB) protein, a methylmalonic aciduria CbIC Type (MMADHC) protein, a 5-Methyltetrahydrofolate-Homocysteine Methyltransferase Reductase (MTRR) protein, a lysosomal membrane protein domain (LMBRD 1) protein, a 5-Methyltetrahydrofolate-Homocysteine Methyltransferase (MTR) protein, a propionyl-CoA protein, a glucose-6-phosphate transporter (G6PT) protein, a glucose-6-phosphatase (G6Pase) protein, a low density lipoprotein receptor (LDLR) protein, a low density lipoprotein receptor adaptor protein 1 (LDLRAP-1 protein), N-acetylglutamate synthetase (NAGS) protein, a carbamoyl phosphate synthetase 1 (CPS1) protein, an ornthine transcarbamylase (OTC) protein, an argininosuccinic acid synthetase (ASS) protein, an argininosuccinase acid lyase (ASL) protein, an arginase (ARG1) protein, a solute carrier family 25 protein, a UDP glucuronosyltransferase 1 family, polypeptide A1 (UGT1A1) protein, a fumarylacetoacetate hydrolyase (FAH), an alanine-glyoxylate aminotransferase (AGXT) protein, a glyoxylate reductase/hydroxypyruvate reductase (GRHPR) protein, an APTase Cu(2+) transporting beta (ATP7B) protein, a phenylalanine hydroxylase (PAH) protein and a lipoprotein lyase (LPL) protein.

2. The cell of claim 1, wherein the cell is selected from the group consisting of a hepatic cell, an induced pluripotent stem cell (iPSC), a hematopoietic stem cell, a hepatic cell, a hepatic stem cell, and a red blood precursor cell.

3. The cell of claim 1, wherein expression of the transgene is driven by an endogenous albumin promoter.

4. The cell of claim 1, wherein the transgene is operably linked to a promoter sequence that drives expression of the transgene.

5. A method of generating a genetically modified cell according to claim 1, the method comprising administering a nuclease and a vector encoding the transgene to the cell such that the transgene is integrated into the endogenous albumin gene.