Researchers Create Mouse Model of Human Retrotransposons

To study the function of retrotransposons in a living organism, researchers have created a mouse model of human L1 retrotransposition. Their work was reported in the December 2002 issue of Nature Genetics.

Only 3% of human DNA encodes the physical body. The remaining 97% of the three billion base pair genome contains over one million genetic structures, called transposons, which have the capacity to jump from one chromosomal location to another. Transposons that jump to a new location via an RNA intermediate are known as retrotransposons. The L1 variety of retrotransposons comprises about one third of the human genome.

To better study retrotransposons, researchers from the University of Pennsylvania School of Medicine (Philadelphia, USA; www.upenn.edu) have bred a mouse to model human L1 retrotransposons.

"There are about one-half million L1 sequences in the human genome, of which 80 to 100 remain an active source of mutation, said senior author Dr. Haig H. Kazazian, Jr., chair of the University of Pennsylvania's department of genetics. "Retrotransposons can cause new genes to emerge that may benefit an organism, or they can kill by knocking out important genes. Overall, however, it seems that they are neutral and add to the apparent sloppiness of the genome. 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.”





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