Genome-wide study of aging and oxidative stress response inDrosophilamelanogaster

Abstract

Aging is a universal but poorly understood biological process. Free radicals accumulate with age and have been proposed to be a major cause of aging. We measured genome-wide changes in transcript levels as a function of age in Drosophila melanogaster and compared these changes with those caused by paraquat, a free-radical generator. A number of genes exhibited changes in transcript levels with both age and paraquat treatment. We also found genes whose transcript levels changed with age but not with paraquat treatment. This study suggests that free radicals play an important role in regulating transcript levels in aging but that they are not the only factors. This genome-wide survey also identifies candidates for molecular markers of aging.A ging is a biological process universal to eukaryotic organisms, and its underlying mechanisms are under intensive study. Genetic analyses of yeast, nematode, fly, and mouse have uncovered a number of genes, whether mutated or misexpressed, that would increase the lifespans of these organisms (1). These genes include superoxide dismutase, a free-radical scavenger; methuselah, a potential G protein-coupled receptor, in Drosophila melanogaster; and p66 shc , an oxidative stress-response gene, in mice (2-5). Lifespan-related genes in Caenorhabditis elegans include clk-1, a gene involved in ubiquinone biosynthesis, and a group of genes involved in an insulin receptor-like signaling pathway: daf-2, age-1, and daf-16 (6, 7). Many mutations that increase lifespan also confer resistance to oxidative stress (1). This finding supports the free-radical hypothesis of aging, which suggests that reactive oxygen species that accumulate with increasing age cause oxidative damage to macromolecules (including nucleic acids, proteins, and lipids) and are causally linked to aging and death (8, 9). Free radicals have been found to regulate the expression of a number of genes that include antioxidant defense genes involved in repairing oxidative damage, as well as genes involved in inducing apoptosis (10, 11). The aging process is also accompanied by changes in the expression patterns of a number of genes (12)(13)(14). How the regulation of gene expression in aging correlates with that in response to oxidative stress, however, is understood poorly. Materials and MethodsConstruction of Microarray. We constructed a microarray containing 7,829 expressed sequence tags (ESTs). This set includes 221 ESTs provided by our lab and 7,608 ESTs generously supplied by K. White (Stanford University, Stanford, CA) and K. Burtis (University of California, Davis). The ESTs were amplified (as described by White et al., ref. 15), and the DNA was mechanically spotted onto polylysine-coated slides (as described by DeRisi et al., ref. 16).Calculation of Survival Rate and Preparation of Fly Tissues. Male flies (w 1118 ) raised in standard cornmeal agar medium, were collected within 24 h after eclosion (17). Approximately 200 flies were maintained in constant darkness in each food bottle at 26-27°C and 60-70% humidity an...

Life extension in Drosophila by feeding a drug

“…There have been various reports of global molecular changes associated with aging, by comparing tissues from young and old animals (37)(38)(39), but it is difficult to determine which events are directly involved in the aging process. The extension of lifespan of Drosophila by treatment with PBA may serve as a useful model.…”

Specific protein homeostatic functions of small heat‐shock proteins increase lifespan

“…Several screens have been performed as an attempt to elucidate the molecular events underlying aging (Zou et al ., 2000; Pletcher et al ., 2002). This has revealed changed expression of several genes involved in many cellular pathways, including members of HSP families.…”

Comparing genomic expression patterns across species identifies shared transcriptional profile in aging

“…Two specific molecular features of aging, the repression of oxidative metabolism genes 12,14 and the correlation between transcriptional profiles of aging and stress 14 , are widely assumed to represent responses to oxidative damage with advancing age. By profiling gene expression at time intervals throughout adulthood in C. elegans and D. melanogaster, we assessed how conserved gene expression programs were implemented over time.…”