Genome complexity: telomere function (Introduction)

by David Turell , Wednesday, March 11, 2015, 17:22 (3544 days ago) @ David Turell

Protect the ends of chromosomes in aging. Also may modify gene expression:-http://www.the-scientist.com/?articles.view/articleNo/42253/title/Rethinking-Telomeres/-"Telomeres are DNA repeats at the ends of chromosomes that protect genetic material from degradation. Because DNA polymerase cannot fully replicate the ends of chromosomes, telomeres shorten each time a cell divides. Telomeres also prevent the ends of chromosomes from fusing to one another by recruiting protective protein caps.-"New work led by Jerry W. Shay and Woodring Wright of the University of Texas Southwestern Medical Center in Dallas demonstrates that telomeres are more than just buffer zones. The team found that as chromosomes fold within the nucleus, telomeres come into contact with faraway genes and alter their expression. As telomeres shorten, which happens with aging, chromosome looping and gene-expression patterns change.-"'I'm delighted with this evidence that the [telomere] sequence may actually be doing some regulation and that the decrease of the sequence in some cells may drastically affect the way they are behaving,” says Mary-Lou Pardue, who studies telomeres at MIT and was not involved in the research. She points out that telomeres are longer and have a more complex sequence than should be necessary to simply protect the chromosome ends.-"Previous work had shown that genes near telomeres are repressed. Shay says that he and his colleagues began to suspect that telomeres were regulating more than just nearby genes when they found that the expression of a gene called ISG15 increased as the telomeres of its chromosomes shortened, even while genes closer to the ends of the chromosomes remained unaffected."