? ? There is mounting evidence that fat regulation involves a complex interplay between the feeding regulatory centers in the nervous system and the regulated transport, partitioning, storage, and utilization of stored fat. It is thought that this homeostatic system has evolved to ensure survival by maintaining energy reservoirs. However, in times of plentiful nutrient supplies, this homeostatic system can cause obesity in individuals with propensity for maintaining large energy stores. Obesity is associated with major heath epidemics worldwide. C. elegans provides an opportunity to identify and analyze fat regulatory genes. Importantly, these analyses are conducted in intact animals in the context of the homeostatic network. Previously, genome-wide RNAi approaches identified over 400 genes that, when inactivated, affect body fat content in C. elegans. These include components of neuroendocrine signaling, transcription, and metabolism. These findings highlight the shared ancestry of C. elegans and mammalian fat regulation and identify many novel pathways. Based on epistasis analyses and mammalian homology searches, 120 priority candidates have been identified. To understand the modes of function and regulation of these genes in intact organisms, i) feeding and locomotary rates of RNAi exposed animals will be determined, ii) quantitative RT-PCR assays will be used to monitor expression levels of a panel of fatty acid, sterol, and sugar metabolic enzymes in RNAi exposed animals, iii) genes identified to affect similar processes will be grouped into genetic pathways, iv) sites of function of fat genes and their products will be determined by GFP tag fusions, iv) these GFP-tag reporters and RT-PCR assays will be used to identify the fat gene inactivations that affect expression levels and/or localizations of the other fat regulatory genes. Similarly, impact of starvation or defects in insulin and serotonin signaling pathways on the fat regulatory genes will be assessed. ? ? ?
