page_title: Knockout rat
section_title: Sleeping beauty (SB) transposons
hierarchical_section_title: Knockout rat / Sleeping beauty (SB) transposons
caption_attribution_description: English: A graphic explaination of the Sleeping Beauty transposon technology used to create knockout rat models
context_page_description: A knockout rat is a genetically engineered rat with a single gene turned off through a targeted mutation used for academic and pharmaceutical research. Knockout rats can mimic human diseases and are important tools for studying gene function and for drug discovery and development. The production of knockout rats was not economically or technically feasible until 2008.
  Technology developed through funding from the National Institutes of Health and work accomplished by the members of the Knock Out Rat Consortium led to cost-effective methods to create knockout rats. The importance of developing the rat as a more versatile tool for human health research is evidenced by the $120 million investment made by the NIH via the Rat Genome Sequencing Project Consortium, resulting in the draft sequence of a laboratory strain of the brown or Norway rat. Additional developments with zinc finger nuclease technology in 2009 led to the first knockout rat with targeted, germline-transmitted mutations. Knockout rat disease models for Parkinson's, Alzheimer's, hypertension, and diabetes using zinc-finger nuclease technology are being commercialized by SAGE Labs.
context_section_description: The sleeping beauty (SB) transposon is a derivative of the Tc1/mariner superfamily of DNA transposons prevalent among both vertebrate and invertebrate genomes. However, endogenous DNA transposons from this family are completely inactive in vertebrate genomes. An active Tc1/mariner transposon, synthesized from alignment of inactive transposons from the salmonid subfamily of elements, was “awoken” to form the transposon named Sleeping Beauty. SB, like other DNA transposons, mobilizes itself via a cut-and-paste mechanism whereby a transposase enzyme, encoded by the transposon itself, excises and re-integrates the transposon at other sites within the genome. The 340 amino acid SB protein recognizes inverted terminal repeats (ITRs) that flank the transposon; it binds to these sequences and catalyzes excision of the transposon. SB then integrates into random sites within the genome, although some studies report very slight preferences for transcriptional units. There is also a simple requirement of a TA-dinucleotide at the target site, like all Tc1/mariner transposons.
  The SB transposon is a powerful tool for insertional mutagenesis in many vertebrate species. It recently exhibited especial utility for germ line mutagenesis in both mice and rats. There are several advantages that make SB a highly attractive mutagen geared toward gene discovery: 1) it has little bias for inserting within particular genomic regions or within specific recognition sequences, 2) de novo insertions of the transposon provide a “tagged” sequence marker for rapid identification of the specific mutation by simple PCR cloning methods, 3) in vivo SB insertional mutagenesis allows multiple mutations to be quickly and easily generated in a single animal, and in a single tissue, such as an adenomatous polyp.
caption: Sleeping Beauty transposon technology
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