REGULATION OF ANTIOXIDATIVE GENES AND AGING

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DESCRIPTION (Adapted from the Applicant's Abstract): The long-term objective of this proposal is to elucidate the regulatory mechanisms governing the expression of CuZn superoxide dismutase (SOD) and catalase, using Drosophila melanogaster as a model system. Superoxide dismutase and catalase are antioxidative enzymes which act in tandem to remove H2O2. The protective role of these enzymes is crucial, because hydrogen peroxide, in the presence of free Fe, can readily lead to the generation of hydroxyl free radicals, thought to be a major culprit in the causation of oxidative damage to biomacromolecules. The accumulation of oxidative damage has been postulated to play a significant role in various disease states, including cancer and atherosclerosis, and aging. Indeed, the overexpression of CuZn SOD in conjunction with catalase has been shown to reduce oxidative molecular damage and extend life span in Drosophila transgenics. The first two Specific Aims of this proposal are designed to test the hypothesis that antioxidative gene expression is subject to multiple levels of regulation. In Specific Aim 1, the temporal and spatial expression of both catalase and CuZn SOD expression will be determined by means of histochemical analysis (using the b-galactosidase reporter gene) and/or immunolocalization. This will be complemented by the second Specific Aim, which is to examine the inducibility of catalase and CuZn SOD, either in response to regimens of oxidative stress or in response to hormonal signals. The objective of Specific Aim 3 is to identify cis-acting regulatory elements that are critical for specific patterns of catalase and CuZn SOD expression in vivo. This will be achieved by fusing modified promoter sequence to reporter genes and characterizing expression patterns in Drosophila transgenics. In specific Aim 4, modified promoters which drive aberrant expression will be fused to the corresponding native gene domains. By placing these transgenes with altered promoters together with non-modified antioxidative transgenes, it should be possible to identify cis-regulatory elements that are essential for life span extension and thus pave the way for isolation of critical trans-acting regulatory factors. Ultimately these studies may lease to development of effective strategies for modulating the rate of aging, which can then be applied to mammalian systems.