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New Lifespan Extension Genes Found

Date:
September 30, 2005
Source:
University of California - Davis
Summary:
New genes tied to lifespan extension in yeast have been identified by researchers from UC Davis and Harvard Medical School.
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New genes tied to lifespan extension in yeast have been identified by researchers from UC Davis and Harvard Medical School.

Drasticallyreducing calorie intake, or caloric restriction, is known to extend thelifespan of species including yeast, worms and rodents. Previousresearch linked a gene called Sir2 with lifespan extension due tocaloric restriction, but worms and yeast that lack Sir2 also livelonger when put on a tough diet, showing that some other genes must beat work.

Researchers led by David Sinclair at Harvard MedicalSchool and Su-Ju Lin at UC Davis' Center for Genetics and Developmentand Section of Microbiology screened for other life-extending genes inyeast. They found a gene called Hst2 that accounts for most of thedifference.

Deleting Hst2 and Sir2 blocked most of the beneficialeffect of caloric restriction. When Hst2 was overexpressed, so that thegene was more active than normal, the yeast lived longer than normal. Athird gene, Hst1, appears to act when both Sir2 and Hst2 are missing.

Sir2and the newly identified Hst genes account for all of thelife-prolonging effects of caloric restriction in yeast, Lin said.

Inyeast, the effects of aging seem to be due to a build-up of toxiccircular DNA molecules that accidentally get copied out of ribosomalDNA, an unstable area of the yeast genome that contains hundreds ofrepeated sequences.

The researchers showed that caloricrestriction drastically reduces recombination of ribosomal DNA, andthat deleting Hst2 and Sir2 blocks this effect.

Very similargenes are found in widely different animals including worms, flies androdents. But the targets of these genes are likely to be different, asthe toxic DNA circles have not been identified in more advancedorganisms, Lin said.

The work was published in the Sept. 16 issue of Science.


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The above story is based on materials provided by University of California - Davis. Note: Materials may be edited for content and length.


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University of California - Davis. "New Lifespan Extension Genes Found." ScienceDaily. ScienceDaily, 30 September 2005. <www.sciencedaily.com/releases/2005/09/050930080433.htm>.
University of California - Davis. (2005, September 30). New Lifespan Extension Genes Found. ScienceDaily. Retrieved May 25, 2015 from www.sciencedaily.com/releases/2005/09/050930080433.htm
University of California - Davis. "New Lifespan Extension Genes Found." ScienceDaily. www.sciencedaily.com/releases/2005/09/050930080433.htm (accessed May 25, 2015).

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