The mouse model of L1 retrotransposition is expected to increase our understanding of the nature of jumping genes and their implication in disease. According to the Penn researchers, the mouse model may also prove to be a useful tool for studying how a gene functions by knocking it out through L1 insertion. Their report is in the December issue of Nature Genetics and currently available online (see below for URL).
"There are about a half million L1 sequences in the human genome, of which 80 to 100 remain an active source of mutation," said Haig H. Kazazian, Jr., MD, Chair of Penn's Department of Genetics and senior author in the study. "This animal model will help us better understand how this happens, as well as provide a useful tool for discovering the function of known genes."
In humans, retrotransposons cause mutations in germ line cells, such as sperm, which continually divide and multiply. Like an errant bit of computer code that gets reproduced and spread online, retrotransposons are adept at being copied from one location and placed elsewhere in the chromosomes. When retrotransposons are inserted into important genes, they can cause disease, such as hemophilia and muscular dystrophy. On the other hand, retrotransposons have been around for 500 to 600 million years, and have contributed a lot to evolutionary change.
"In the grand scheme of evolution, retrotransposons have behaved like fickle gods, arbitrarily wreaking havoc in some and benefiting others," said Kazazian. "Retrotransposons can cause new
Contact: Greg Lester
University of Pennsylvania School of Medicine