The worldwide epidemic of obesity has spurred increased interest in the molecular pathways and physiological mechanisms regulating energy homeostasis and fat storage (Flier 2004). There is a correlation between obesity and signs of premature aging, such as increased prevalence of age-related disease, shortened telomere length, and reduced life-expectancy (Olshansky 2005). However, the mechanisms by which fat metabolism and longevity are linked remain unclear. Given the difficulty of making causative associations in human studies, and the length and cost of murine aging studies, research in C. elegans and Drosophila has driven our understanding of the regulation of longevity. This proposal will investigate the role of a novel lipid-signaling pathway in the regulation of longevit, and characterize the effects of a potential longevity-promoting naturally occurring metabolite. Approach: In preliminary studies using C. elegans and Drosophila, we have found that increasing lipolysis is a conserved mechanism of lifespan extension. Additionally, we have found that when we induce lipolysis by increasing expression of lipase genes, levels of the lipid messenger oleoylethanolamide (OEA) are increased. Oral administration of OEA to C. elegans acts on the nuclear hormone receptor nhr-49 to induce the expression of genes we have found to promote longevity. In mammals, OEA is known to decrease obesity and increase fatty acid catabolism (Fu 2003). We propose that OEA is a longevity promoting metabolite and aim to identify the mechanism by which OEA influences aging and metabolism through studies in C. elegans and Drosophila.
In Aim 1, we will use cell-based GAL4 luciferase reporter assays and RNA-sequencing to characterize the transcriptional response to OEA and its dependence on the nuclear hormone receptor nhr-49. Additionally, we will test the effect of feeding OEA on C. elegans lifespan.
In Aim 2, we will utilize similar assays to test the role of the fatty acid bindig protein lbp-8 in facilitating the actions of OEA. Additionally, we will use high-throughput assessments of mitochondrial activity by the measurement of oxygen consumption rate to characterize the metabolic effects of these interventions.
In Aim 3, we will use advanced genetic manipulations of Drosophila to assess the tissues involved in the regulation of longevity by changes in lipid metabolism, and use similar metabolic and lifespan assays to assess the conservation of this pathway between worms and flies.
The worldwide obesity epidemic necessitates an increased understanding of the relationship between fat metabolism and aging to help prevent an increase in age-related metabolic diseases and decreased life expectancy. We aim to characterize a potential obesity-reducing and longevity-promoting pathway involving the naturally occurring lipid messenger oleoylethanolamide (OEA). Characterization of this pathway will enhance our understanding of the relationship between lipid metabolism and aging.