“Jumping Genes” May Contribute to Aging-Related Brain Defects

As the body ages, the physical effects are notable; wrinkles in the skin appear, physical exertion becomes harder. But there are also less visible processes going on. Inside aging brains there is another phenomenon at work, which may contribute to age-related brain defects. In a paper published online on April 7, 2013 in the journal Nature Neuroscience, Cold Spring Harbor Laboratory (CSHL) Associate Professor Joshua Dubnau and colleagues show that so-called "jumping genes," or transposons, increase in abundance and activity in the brains of fruit flies as they age. Originally discovered at CSHL by eventual Nobel Prize winner Professor Barbara McClintock (photo) while working on maize (corn) in the 1940s, transposons are typically repeat DNA sequences that insert themselves into the DNA of an animal or plant. The moniker "jumping genes" comes from the fact that, when activated, transposons can reinsert themselves, or transpose, into another part of the genome. In the course of doing so, they are thought to either provide variations in genetic function or, especially in the germline, induce potentially fatal disruptive defects. The lifespan of a fruit fly can be measured in days. The average fruit fly lives for somewhere between 40-50 days. But these flies provide a powerful model with which to get at the genetics of phenomena like aging and brain function, including memory. Dr. Dubnau's interest was piqued by an experiment in which his team showed that when the activity of a protein called Ago2 (Argonaute 2) was perturbed, so was long-term memory—which was tested using a trained Pavolvian response to smell. "This is a neurodegenerative defect that gets profoundly more apparent with age of the flies," notes Dr. Dubnau.
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