The Connection Between Age And Genetic Damage Illuminated by Age-Related Changes

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The Connection Between Age And Genetic Damage Illuminated by Age-

Related Changes In DNA Repair

http://www.medicalnewstoday.com/medicalnews.php?newsid=54925

Researchers have uncovered a new way in which the aging process is

linked to DNA damage--which occurs normally as a result of cell

metabolism and environmental influences--and the various ways in

which cells repair that damage. In the new work, researchers found

that cells in young fruit flies make use of a different mix of

molecular DNA-repair mechanisms compared to cells in older flies.

The findings are reported by Engels and colleagues at the

University of Wisconsin and appear in the October 24th issue of the

journal Current Biology, published by Cell Press.

DNA repair is essential for the accurate preservation of genetic

information and to ensure the healthy functioning of cells, and a

connection between aging and DNA damage has long been suspected. One

line of evidence supporting the connection is that defects in

certain genes needed for DNA repair produce maladies that mimic

those of accelerated aging. In humans and other mammals, these

effects include elevated occurrence of malignancies, osteoporosis,

hearing loss, graying of hair, and hair loss. It is also known that

DNA damage accumulates with age in cells of a variety of tissue

types.

Breaks in the DNA chain have a variety of causes and occur

frequently in the course of natural cellular processes. Repairing

such breaks is an essential but hazardous process, often leaving

missing or added bases at the point of repair. Cells possess a

variety of methods for repairing broken DNA, and the cell's " choice "

of how to repair a particular break can be critical. Some repair

methods are simple but error prone, whereas the more accurate

methods have elaborate molecular requirements and are probably much

slower.

The new results show that the reproductive cells of young flies tend

to use the rough-and-ready repair processes that do not involve

extensive DNA synthesis and do not require a matching DNA template

for the repair. As the organisms age, however, the same kind of DNA

breaks are repaired primarily by the slower but much more accurate

methods that make use of a matching template. These findings raise

the question of whether the rapid but risky methods of DNA repair

used by cells of young individuals contribute to the accumulation of

genetic damage, and perhaps to the aging process itself. Older cells

may use the safer repair methods, but they still carry the genetic

damage incurred during DNA repair in the fly's " reckless " youth.

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The researchers include R. Preston, , and

R. Engels of the University of Wisconsin in Madison,

Wisconsin. This work was supported by National Institutes of Health

GM30948.

Preston et al.: " Age-Dependent Usage of Double-Strand Break Repair

Pathways. " Publishing in Current Biology 16, 2009-2015, October 24,

2006 DOI 10.1016/j.cub.2006.08.058. http://www.current-biology.com/