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Heat Shock, Future Shock at NIA's 8th Shock Lecture

By Michael Miller

Shocking doesn't adequately describe the nature of the talk given by guest lecturer Dr. S. Michal Jazwinski at NIA's 8th annual Nathan W. Shock Memorial Lecture on Aging.

Words like enlightening, informative and entertaining seem more appropriate. As part of the introduction to the lecture, it was humorously mentioned that Esquire magazine once gave Jazwinski one of its Dubious Achievement Awards. Based on Jazwinski's cloning of the LAG1 longevity gene in yeast, and the misquoted extrapolation that humans could live 600 years, Esquire expressed its befuddlement at what might be done with all of the resulting 600-year-old people, or tons of very old yeast. Jazwinski's lecture, however, was one that commemorated and advanced the understanding of Dr. Nathan Shock's landmark research and interest in aging.

Jazwinski, professor of biochemistry and molecular biology at Louisiana State University Medical Center in New Orleans, prefaced his talk, "Longevity, Genes, and Aging: The View Provided by a Genetic Model System," by discussing the history of aging research and some of the rather antiquated ideas about the science of aging that date to the 16th century.

Jazwinski's research is done mainly in yeast cells, which can divide only a limited number of times, thus allowing researchers to observe and calculate the lifespan of individual cells. He has identified nine genes that play a role in lifespan in yeast, and he spent a good part of the lecture identifying those genes and the interactive role they play in the life of a yeast cell.

Two of the most important genes he discussed were the RAS1 and RAS2 genes, which function as nutritional sensors whose role is to achieve a sort of cellular homeostasis. RAS1 seems to shorten lifespan while RAS2 prolongs it. By genetic manipulation in his lab, Jazwinski can overexpress RAS2 in yeast, which can lead to an extension of lifespan. Another gene, PHB1, may be essential for long life. Jazwinski has concluded there is an additive effect among a number of genes that extend lifespan, suggesting more than one pathway to longevity.

Heat shock, with its fascinating implications for humans, was the next topic. In experiments with yeast, Jazwinski found that inducing heat tolerance led to a longer lifespan. However, if heat shock was administered chronically, lifespan seemed shortened.

Jazwinski says, "many people believe that chronic stress contributes to human aging, especially brain aging, and only additional research will tell us if chronic stress in yeast will broaden our knowledge of chronic stress in humans."

In conclusion, Jazwinski brought various disparate theories of aging together. In addition to genes and heat shock, telomeres, the tips of chromosomes, have been mentioned as possible determinants of aging and cancer. Jazwinski doesn't believe that telomere shortening, as such, is the key aspect of their role in determining longevity. He thinks a cell's organization, which is essentially the way various pathways a cell uses to survive integrate with each other, is determined genetically. Disruption of this organization is what leads to aging.

As part of his endeavor to help all of us avoid "future shock," Jazwinski is currently studying the nonlinearity inherent in the dynamic process of aging. As evidenced by the probing nature of the questions at the end of his talk, everyone at NIA is eager to see what revelations about aging Jazwinski comes up with next.

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