U.S. researchers find enzyme affects aging process

By Andrea Orr

LOS ANGELES (06/09/97 Reuter News) -

Researchers said Monday they had found an enzyme that appeared to play a role in the pace at which various organisms age and when they die. They said the enzyme is found in virtually all life forms and in every tissue in the human body, with particularly high concentrations in the brain. Although it does not explain all of the mysteries of aging nor offer hope for developing anything like a youth potion, doctors said it could potentially be used in developing treatments for certain age-related disorders like cataracts and Alzheimer's Disease. The research was conducted at the University of California at San Francisco, where doctors genetically engineered mice so their bodies did not have any of the enzyme, known as PCMT  or L-isoaspartyl methyltransferase. The enzyme-deficient mice were smaller than normal mice and all suffered seizures and died before they were 60 days old, the equivalent of late adolescence in a mouse's lifespan. While previous studies had established the enzyme played a role in the repair of damaged proteins in the laboratory, it had not been shown to affect an organism's overall aging process. These new findings were published in the June 10 issue of the Proceedings of the National Academy of Sciences. ``When we looked at the mice that we had genetically engineered on a biochemical level, we found that there was a large increase in the number of damaged proteins in their cells compared to normal mice,'' said the author of the study, Dr. Edward Kim, a postdoctoral fellow at the UCSF-affiliated Gladstone Institute of Cardiovascular Disease.

Kim said the enzyme appeared to work by recognizing defective proteins and repairing them so they could continue to function. ``There are several theories about how and why cells age, among them that a cell ages when it can't rid itself of its garbage -- such as defective proteins,'' Kim added. ``In this study, the brain cells seemed particularly sensitive to the accumulation of aged proteins.'' Kim said there could also be external reasons for a cell's aging, such as exposure to carcinogens or other environmental factors. But he said a number of age-related diseases like cataracts and Alzheimer's were characterized at least in part by a buildup of damaged protein in the affected tissue.

  C.Mallery

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