NECROTIC CELL DEATH AND HELICASES IN C ELEGANS AGING

Exploiting the experimental strengths of animal systems to elucidate genetic, cellular and biochemical mechanisms of aging may ultimately influence design of novel interventions that could reduce or delay age- related degenerative processes in human. Here we propose to pioneer work on two projects expected to provide new insight into aging mechanisms in Caenorhabditis elegans. The first project is focused on the role of degenerative cell death in the aging process. We have noted that the bodies of aging nematodes feature vacuoles and cellular inclusions reminiscent of those that occur during necrotic-like injury-induced death. We have developed genetic and molecular tools that now position us to address Aim 1: to test the hypothesis that degenerative cell death is an important/essential component of C. elegans aging. We will correlate necrotic-like cell death with nematode age, compare extent of degeneration in wild type vs. long-lived C. elegans mutants, and test for the influence of mutations that disrupt degenerative cell death on aging and lifespan. To test a potential biomarker of aging, we will also assay for evidence of lipid peroxidation in degenerating structures. This study is of fundamental interest because damage to cellular DNA, proteins and organelles is known to accumulate in aging cells and to contribute to their dysfunction, but whether injury-induced cell death contributes in a critical way to the aging of an organism has remained a mystery. The objective of the second project is AIM II: to generate and characterize mutations in C. elegans genes related to human Werner's syndrome gene WRN and yeast gene SGS1. Although C. elegans is a powerful genetic system, mutations that accelerate senescence have not yet been characterized in this organism. In the long-term we hope to identify biomarkers of aging that enable us to identify such mutations. Here we will attempt to develop a model for "accelerated senescence" in C. elegans by identifying deletion mutants of two related helicase family members that are implicated in accelerated senescence phenomena in humans and in yeast. Mutants will be characterized for evidence of chromosome instability, developmental defects, age-related phenotypes and interactions with other genes that influence lifespan. Generation of a nematode model for these aging disorders should extend understanding of the influence of helicase family members on senescence and at the same time provide data that may facilitate future genetic screens for mutations that cause similar phenotypes.