bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microtubule protein phosphorylation in neuroblastoma cells and neurite growth
Authors: DÍAz-Nido J. , Armas-Portela R. , Correas I. , Dominguez J. E. , Montejo E. , Avila J. 
Published: May 2013

ABSTRACT
The development of highly asymmetrical neurones from undifferentiated neuroblasts involves the extension of processes (axon and dendrites), that depends on the assembly of an inner microtubule scaffolding. Clonal cell lines of neuronal origin, N2A and NIE-115 neuroblastoma cells, have been chosen as model systems to study the modifications of microtubule protein which accompany the outgrowth of axon-like processes (neurites). Neuroblastoma cells grow as proliferating and undifferentiated cells in standard culture medium but can be considered as committed neuronal precursors. Thus, they are characterized by a high content of tubulin, including the minor neuronal-specific isoform, and of MAPs including MAP1B and tau-like proteins. Serum withdrawal from the culture medium results in the extension of axon-like processes which is paralleled by a net increase in the amount of assembled tubulin. However, there is not any increase in the total amount of either tubulin or major MAPs which suggests an involvement of other regulatory factors in the promotion of microtubule assembly. Of relevance in this respect is the fact that j83-tubulin, MAP1B, and tau-like proteins become phosphorylated during neurite extension.
A casein kinase Il-like enzyme may be involved in some of these phosphorylation events. This enzyme is primarily localized to the nuclei in undifferentiated neuroblastoma cells, whereas a wider distribution of the enzyme between the nucleus and the cytoplasm is found in differentiating neuroblastoma cells. It thus appears plausible that a modified sorting of casein kinase II into the nucleus and the cytoplasm may be involved in the triggering of the phosphorylation of microtubule proteins during neuroblastoma cell differentiation.
Identification of Fos target genes by the use of selective induction systems
Authors: Braselmann Sylvia , Bergers Gabriele , Wrighton Christopher , Graninger Paula , Superti-Furga Giulio , Busslinger Meinrad 
Published: May 2013

ABSTRACT
c-Fos is a major component of the transcription factor AP-1 which has been implicated in the control of cell proliferation and differentiation as well as in transformation. In order to identify Fos target genes involved in these processes, we have taken advantage of the regulatory properties of the hormone-binding domain of the human estrogen receptor to develop transcriptional and post-translational induction systems, both of which allow selective elevation of Fos activity within a cell. Using this approach we have searched for Fos-responsive genes in rat fibroblasts and PC12 cells. Here we describe the identification and regulation of five Fosresponsive genes encoding a transcription factor (Fra-1), a secreted protein (Fit-1), a biosynthetic enzyme (ODC) and two membrane-associated proteins (annexin II and V), respectively. The post-translational induction system was also used to study the Fos-mediated block of neuronal differentiation of PC12 cells. These experiments demonstrate that Fos activity is dominant over NGF function and interferes with the expression of late NGF-inducible genes.
The role of the transcriptional activator protein DBP in circadian liver gene expression
Authors: Wuarin JÉRÔMe , Falvey Eileen , Lavery Dan , Talbot Dale , Schmidt Ed , Ossipow Vincent , Fonjallaz Philippe , Schibler Ueli 
Published: May 2013

ABSTRACT
DBP, a liver-enriched transcriptional activator protein of the leucine zipper protein family, accumulates according to a very strong circadian rhythm (amplitude approx. 1000-fold). In rat parenchymal hepatocytes, the protein is barely detectable during the morning hours. At about 2 p.m., DBP levels begin to rise, reach maximal levels at 8 p.m. and decline sharply during the night. This rhythm is free-running: it persists with regard to both its amplitude and phase in the absence of external time cues, such as daily dark/light switches. Also, fasting of rats for several days influences neither the amplitude nor the phase of circadian DBP expression. Since the levels of DBP mRNA and nascent transcripts also oscillate with a strong amplitude, circadian DBP expression is transcriptionally controlled. While DBP mRNA fluctuates with a similar phase and amplitude in most tissues examined, DBP protein accumulates to high concentrations only in liver nuclei. Hence, at least in nonhepatic tissues, cyclic DBP transcription is unlikely to be controlled by a positive and/or negative feedback mechanism involving DBP itself. More likely, the circadian DBP expression is governed by hormones whose peripheral concentrations also oscillate during the day. Several lines of evidence suggest a pivotal role of glucocorticoid hormones in establishing the DBP cycle.
Two genes whose mRNAs and protein products accumulate according to a strong circadian rhythm with a phase compatible with regulation by DBP encode enzymes with key functions in cholesterol metabolism: HMG-coA reductase is the rate-limiting enzyme in cholesterol synthesis; cholesterol 7-a hydroxylase performs the rate-limiting step in the conversion of cholesterol to bile acid. DBP may thus be involved in regulating cholesterol homeostasis.
Characterization of recombinant E-cadherin (uvomorulin) expressed in insect cells
Authors: Herrenknecht Kurt , Kemler Rolf 
Published: May 2013

ABSTRACT
Cadherins are Ca2+-dependent cell adhesion molecules that mediate cell adhesion by homophilic binding. Structural and functional analysis of the extracellular part of cadherins that mediates this binding has often been hampered by the availability of sufficient amount of protein. Therefore, we have expressed the extracellular region of E-cadherin (uvomorulin) using the baculovirus expression vector system (BEVS). A recombinant baculovirus was generated that encodes the signal peptide, the precursor region and the extracellular part of the mature protein, under the control of the promotor for polyhedrin. Infection of insect cells with recombinant virus led to the expression of about 40 mg of the E-cadherin fragment per 2×109 infected cells. About half of the protein synthesized was secreted, either as mature protein or in its unprocessed form. The precursor peptide was removed by trypsin treatment in the presence of Ca2+ and recombinant protein was purified to homogeneity. Biochemical characterization of the recombinant protein revealed a high degree of similarity with the mouse wild-type protein. Recombinant protein exhibited the known resistance to trypsin in the presence of Ca2+ and was recognized by two different conformation-sensitive monoclonal anti-E-cadherin antibodies. Rabbit antibodies made against the recombinant protein recognized E-cadherin from different species. In spite of the high degree of structural resemblance recombinant E-cadherin was not able to inhibit E-cadherin mediated cell-cell adhesion.
Patches and fences: probing for plasma membrane domains
Authors: Edidin Michael 
Published: May 2013

ABSTRACT
Cell plasma membranes appear to be composed of domains, patches whose composition and function differ from the average for an entire membrane surface. Proteins and lipids may be segregated into domains by different mechanisms. Some of these mechanisms are discussed, followed by a summary of the evidence for membrane domains obtained in my laboratory. This evidence is largely based on measurements of the lateral diffusion of membrane proteins and lipids. Recent new approaches to the interpretation of lateral diffusion measurements, consideration of so-called fractal or long time-tails promise to give new insights into the stability and lifetime of membrane domains.
Responses to Wnt signals in vertebrate embryos may involve changes in cell adhesion and cell movement
Authors: Moon Randall T. , DeMarais Alyce , Olson Daniel J. 
Published: May 2013

ABSTRACT
Wnt genes encode secreted glycoproteins, and, because of their homology with the Drosophila segment polarity gene wingless, are likely to play important roles as modulators of local intercellular signalling during embryonic development. Although little is known of the mechanisms by which Wnts signal in an autocrine or paracrine manner, it is increasingly clear that cells can respond rapidly to Wnt signals in the absence of transcription, and that these responses may include changes in cell adhesion and cell movement. We review recent evidence from studies on Xenopus laevis and other sys-terns, which demonstrate that (1) a subset of Wnts modulate gap junctional permeability, which may be a reflection of changes in cadherin-mediated cell adhesion, (2) embryos express β-catenin and plakoglobin, which are homologs of the armadillo gene products, known to be involved in the wingless signalling pathway, and known to be found at cell junctions, and (3) overexpression of specific Wnts in Xenopus embryos leads to clear changes in cell behavior and movement.
Defective acidification of the biosynthetic pathway in cystic fibrosis
Authors: Barasch Jonathan , Al-Awqati Qais 
Published: May 2013

SUMMARY
Cystic fibrosis is associated with defective epithelial sodium chloride and fluid secretion in epithelia. In addition, there is widespread reductions in sialylation of secreted proteins and increases in the sulfation and fucosylation of mucus glycoproteins. The major morbidity in the disease is due to the colonization of respiratory epithelia by Pseudomonas. The cystic fibrosis gene (CFTR) is a cyclic AMP activated Cl channel, which when mutated is retained in the endoplasmic reticulum. We postulate that this Cl channel is responsible for effective acidification of the Golgi. In CF cells, we demonstrate the Golgi pH is higher than in normal cells and suggest that the abnormalities in glycoprotein biosynthesis is due to changes in the kinetics of sialyl transferase, a pH sensitive enzyme. Defects in sialylation also result in decreased sialylation of glycolipids and asialogangliosides are potential Pseudomonas receptors.
Phenotypic conversions in renal development
Authors: Herzlinger D. , Abramson R. , Cohen D. 
Published: May 2013

ABSTRACT
The transporting epithelia of the kidney are derived from an embryonic rudiment containing two distinct cell populations: ureteric bud epithelia and mesenchymal cells of the metanephric blastema. The ureteric bud is a caudal outgrowth of the Wolffian Duct and gives rise to the renal collecting system by branching morphogenesis. The metanephric blastema gives rise to diverse cells of the nephron after receiving an inductive stimulus. It has been proposed that mesenchymal progenitors of the metanephric blastema derive directly from intermediate mesoderm, although this hypothesis has never been tested directly. Utilizing direct lineage analysis techniques we demonstrate, in an organ culture system, that mesenchymal nephron progenitors are immediate descendants of ureteric bud epithelia. Ureteric bud epithelia can give rise to mesenchymal nephron progenitors that populate the metanephric blastema by undergoing an epithelial-to-mesenchymal transition followed by delamination. If this process occurs in vivo, renal morphogenesis can be characterized by two phenotypic conversions: an epithelial-to-mesenchymal transition leading to the generation of mesenchymalnephron progenitors, followed by a mesenchymal-to-epithelial transition leading to the generation of diverse nephron epithelial cell types. We have immortalized an embryonic renal mesenchymal cell line and demonstrate that the clonal cell line, RSTEM-1, undergoes phenotypic conversions in vitro, providing a suitable model to study the regulation of the epithelial phenotype.
Recognition and processing of damaged DNA
Authors: Lindahl Tomas 
Published: May 2013

ABSTRACT
Base excision-repair, which is required for correction of spontaneous hydrolytic and oxidative damage to DNA as well as lesions inflicted by alkylating agents, is a relatively well understood repair pathway. Mammalian factors involved in this pathway are reviewed, with emphasis on current uncertainties.
Most DNA replication and repair enzymes in mammalian cell nuclei, e.g. DNA polymerases α, β, δ, and ε, have direct counterparts in yeast. In contrast, the abundant enzymes in mammalian cell nuclei that bind and are activated specifically by DNA strand interruptions, poly(ADP-ribose) polymerase and DNA-dependent protein kinase, have not been detected in yeast; nor has p53, which is elevated in response to DNA strand breaks. We have found a family of four distinct DNA ligases in human cell nuclei, whereas only a single DNA ligase has been detected in yeast. It would appear that the cellular responses to DNA strand breaks may differ markedly between higher and lower eukaryotes.
Appearance of apparently ubiquitin-conjugated lκB-α during its phosphorylation-induced degradation in intact cells
Authors: Traenckner E. Britta-Mareen , Baeuerle Patrick A. 
Published: May 2013

ABSTRACT
NF-κ B is a dimeric protein that serves to initiate gene transcription in higher eukaryotic cells in response to mainly pathogenic stimuli. Its activity is controlled by a third inhibitory subunit, called IκB. When IκB is bound, NF-κB cannot bind to DNA or enter the nucleus but is stored in a latent cytoplasmic form. Upon stimulation of cells IκB is released, which allows the activation of NF-κB. We have analyzed the molecular mechanism underlying the removal of IκB-α. Distinct extracellular stimuli lead to a phosphorylation of IκB-α on serines 32 and 36 by a yet unidentified kinase. These modifications do not directly dissociate IκB from NF-κB but render the inhibitor highly susceptible for proteolytic degradation by, presumably, the proteasome. In this paper, we report for the first time that higher molecular mass forms of IκB-α occur under conditions that lead to a phosphorylation of IκB-α and activation of NF-KB. These IκB-α variants had discrete molecular masses and were most prominent in cells overexpressing IκB-α, suggesting the covalent modification of IκB-α by ubiquitin conjugation. The proteasome inhibitor Cbz-Ile-Glu(O-t-Bu)-Ala-leucinal (PSI), which stabilizes the phospho form of IκB-α, only slightly increased the amount of conjugates indicating that the conjugation of IκB-α with ubiquitin was the rate-limiting step in I κ B-α degradation, and not its phosphorylation or proteolysis. Our data suggest that conjugation of IκB-α with ubiquitin is an intermediate reaction in the phosphorylation-controlled degradation of IκB-α and the subsequent activation of NF-κB.
Regulation of cell proliferation and differentiation by Myc
Authors: Hopewell Robert , Li Linheng , MacGregor Douglas , Nerlov Claus , Ziff Edward B. 
Published: May 2013

ABSTRACT
Myc is a nuclear phosphoprotein which controls cellular proliferation, most likely by regulating gene activity. The finding that the neuronal model cell line PC12 lacks the Myc DNA binding partner, the Max protein, and the demonstration that Myc is a repressor of gene activity as well as a transactivator, lead to models for Myc action in regulating cell growth.
Regulation of transcription by E2F1/DP1
Authors: Martin Klaus , Trouche Didier , Hagemeier Christian , Kouzarides Tony 
Published: May 2013

ABSTRACT
The E2F1 transcription factor, in co-operation with DPI, controls the expression of several S-phase specific genes. This activity is most likely responsible for the oncogenic and S-phase inducing properties of E2F1, suggesting that this transcription factor plays a key role in regulating the cell cycle. The transcriptional activation functions of E2F1 are resident in a small C-terminal domain which can inde-pendently activate transcription. Here we review the protein-protein interactions which impinge upon and regulate this activation domain and put forward some models on their mechanism of action.
Does the Wilms’ tumour suppressor gene, WT1, play roles in both splicing and transcription?
Authors: Charlieu Jean-Paul , Larsson Stefan , Miyagawa Kiyoshi , Heyningen Veronica van , Hastie Nicholas D. 
Published: May 2013

ABSTRACT
The Wilms’ tumour suppressor gene (WT1) encodes a protein(s) with 4 zinc fingers that is essential for the development of the genitourinary system. A considerable body of evidence exists to support the idea that WT1 binds DNA and functions as a transcription factor. However, we have shown recently by confocal microscopy and immunoprecipitation studies that a significant proportion of WT1 is associated with splice factors in kidney cell lines, fetal tissues and transfected Cos cells. Different isoforms of WT1 are produced by an alternative splice that leads to the presence or absence of a 3 amino acid insertion (KTS) between zinc fingers 3 and 4. We have shown that these different forms localise differently in the nucleus. The +KTS form mainly localises with splice factors, the −KTS form mainly with transcription factors. Here we propose a model to account for these different localisations. Also, we discuss the possible significance of these findings.
Protein kinases in the control of mitosis: focus on nucleocytoplasmic trafficking
Authors: Gallant P. , Fry A. M. , Nigg E. A. 
Published: May 2013

ABSTRACT
The eukaryotic cell nucleus is a highly dynamic organelle. This is illustrated most dramatically during mitosis, when the nuclear envelope breaks down, the nuclear lamina disassembles, chromosomes condense, and a microtubulebased spindle apparatus distributes sister chromatids to the dividing daughter cells. Many of these dramatic changes in nuclear architecture and microtubule organization are controlled by phosphorylation and dephosphorylation events. Whereas the cardinal role of cyclin-dependent kinases (CDKs) in the regulation of mitosis is well established, there is now clear evidence for the requirement of additional mitotic protein kinases. Studies into the regulation of CDKs and other mitotic kinases have revealed that these enzymes undergo cell cycle dependent changes in subcellular distribution, suggesting that localization may contribute to regulating their activities. This article describes some recent findings relating to the nucleocytoplasmic translocation of CDK/cyclin complexes at the onset of mitosis. In addition, it summarizes recent information on two novel human protein kinases which have been implicated in the control of mitotic progression.
Analysis of the temporal program of replication initiation in yeast chromosomes
Authors: Friedman Katherine L. , Raghuraman M. K. , Fangman Walton L. , Brewer Bonita J. 
Published: May 2013

ABSTRACT
The multiple origins of eukaryotic chromosomes vary in the time of their initiation during S phase. In the chromosomes of Saccharomyces cerevisiae the presence of a functional telomere causes nearby origins to delay initiation until the second half of S phase. The key feature of telomeres that causes the replication delay is the telomeric sequence (C1-3A/G1-3-3T) itself and not the proximity of the origin to a DNA end. A second group of late replicating origins has been found at an internal position on chromosome XIV. Four origins, spanning ∼140 kb, initiate replication in the second half of S phase. At least two of these internal origins maintain their late replication time on circular plasmids. Each of these origins can be separated into two functional elements: those sequences that provide origin function and those that impose late activation. Because the assay for determining replication time is costly and laborious, it has not been possible to analyze in detail these ‘late′ elements. We report here the development of two new assays for determining replication time. The first exploits the expression of the Escherichia coli dam methylase in yeast and the characteristic period of hemimethylation that transiently follows the passage of a replication fork. The second uses quantitative hybridization to detect two-fold differences in the amount of specific restriction fragments as a function of progress through S phase. The novel aspect of this assay is the creation in vivo of a non-replicating DNA sequence by site-specific pop-out recombination. This non-replicating fragment acts as an internal control for copy number within and between samples. Both of these techniques are rapid and much less costly than the more conventional density transfer experiments that require CsCl gradients to detect replicated DNA. With these techniques it should be possible to identify the sequences responsible for late initiation, to search for other late replicating regions in the genome, and to begin to analyze the effect that altering the temporal program has on chromosome function.
Stepwise assembly of initiation complexes at budding yeast replication origins during the cell cycle
Authors: Diffley John F. X. , Cocker Julie H. , Dowell Simon J. , Harwood Janet , Rowley Adele 
Published: May 2013

ABSTRACT
DNA replication is a pivotal event in the cell cycle and, as a consequence, is tightly controlled in eukaryotic cells. The initiation of DNA replication is dependent upon the completion of mitosis and upon the commitment to complete the cell cycle made during G1. Characterisation of the protein factors required for initiating DNA replication is essential to understand how the cell cycle is regulated. Recent results indicate that initiation complexes assemble in multiple stages during the cell cycle. First, origins are bound by the multisubunit origin recognition complex (ORC) which is essential for DNA replication in vivo. ORC, present at little more than one complete complex per replication origin, binds to origins immediately after initiation in the previous cell cycle. ORC binding occurs by the recognition of a bipartite sequence that includes the essential ARS consensus sequence (ACS) and the functionally important Bl element adjacent to the ACS. A novel pre-replicative complex (pre-RC) assembles at origins at the end of mitosis in actively cycling cells and remains at origins until DNA replication initiates. Finally, Dbf4, which is periodically synthesised at the end of Gi, interacts with replication origins. Dbf4-origin interaction requires an intact ACS strongly suggesting that interaction occurs through ORC. Dbf4 interacts with and is required for the activation of the Cdc7 protein kinase and together, Dbf4 and Cdc7 are required for the Gi-S transition. Separate regions of Dbf4 are required for Cdc7- and origin-interaction suggesting that Dbf4 may act to recruit Cdc7 to replication origins where phosphorylation of some key component may cause origin firing.
Edward Dembowski – życie i twórczość „czerwonego kasztelanica”
Authors: Jezioro Artur 
Published: May 2013

Edward Dembowski – life and work of “the red castellan’s‑ son”
Edward Dembowski is one of the most controversial figures of Polish history in the nineteenth century. Outstanding conspirator, totally dedicated to the democratic and revolutionary ideals, tirelessly tried to trigger off another national uprising, combined with the social revolution. He was primarily a man of action, but also left a number of writings, showing his achievements in the field of philosophy, literature and journalism. Dembowski’s figure is surrounded by legend, also because of his tragic death at a young age. But in fact, the “red castellan” is surrounded by two legends – the black one and the white one. According to the first of them, the character of the following article was an insane communist and revolutionary, guilty of bloodshed in the name of utopian ideals. The second legend, positive, presents his person as the heroic envoy, one of the national heroes of the nineteenth‑century, totally dedicated to the national and social causes, finally dying in the name of these ideals. Which of the two legends is closer to the truth? I hope that this article, which aims to provide an overview of the most important facts about the life of Edward Dembowski and to present his political, social and philosophical views, will help readers find the answer to this question. The first part of the paper primarily describes the life and activity of Edward Dembowski, while the second one focuses on his philosophical views.