The incidence of obesity is increasing at an alarming rate in Western cultures, leading to its classification as an epidemic. In light of this epidemic, there is great impetus to better elucidate the processes that regulate fat production, storage, and release. The ability to regulate fat storage is a fundamental process required for survival of species ranging from mammals to invertebrates. It has therefore been suggested that diverse model organisms may be exploited in the study of fat metabolism. Very recent studies have demonstrated that the nematode Caenorhabditis elegans provides a useful model for identification of genes affecting fat storage. An RNAi screen to inactivate more than 16,000 genes in C. elegans and screen for alterations in fat storage identified 305 genes that reduced, and 112 genes that increased body fat upon inactivation (Ashrafi et al., 2003). More than 50% of these genes have mammalian homologs not previously implicated in regulating fat storage, and represent excellent candidates for having potential roles in human fat metabolism. In this proposal, we will evaluate several candidate """"""""fat genes"""""""" identified in C. elegans by generating and characterizing gene knockout mouse models. To circumvent the traditional time consuming and laborious process of generating gene knockouts via recombination in embryonic stem (ES) cells, we will utilize a resource containing thousands of pre-fabricated ES cell lines containing gene-trap insertions. We have identified 22 existing ES cell lines carrying inactivating insertions within mouse homologs of C. elegans fat genes identified by Ashrafi et al., which are available from the BayGenomics Gene-Trap Consortium. We have confirmed that several of these genes are prominently expressed in mouse adipose tissue, and hypothesize that these genes, which have already been shown to play a role in fat storage in C. elegans, may affect fat development or metabolism in mammals. We will utilize the existing gene-trap ES cell lines to generate mouse knockout strains for several of the putative """"""""fat genes"""""""", and characterize them for adipose tissue mass, glucose and energy metabolism. This pilot study will reveal whether """"""""fat genes"""""""" identified in the invertebrate C. elegans have a similar role in mammals, and may identify novel genes involved in fat storage and metabolism.
| Reue, Karen; Vergnes, Laurent (2006) Approaches to lipid metabolism gene identification and characterization in the postgenomic era. J Lipid Res 47:1891-907 |
