of work: Type 2 diabetes is one of the most common diseases in the elderly population of the USA and is often associated with obesity. In all these cases there is alteration of glucose metabolism and insulin signaling. We have identified novel genes involved in fat metabolism and insulin signaling. (1) Using primers to known glucagon-like peptide receptor we searched for novel receptors expressed in mouse fat. We isolated a full length clone encoding a novel putative seven transmembrane domain protein. This gene is differentially expressed in adipocytes. The expression is increased (by 2-3 fold) in (a) adipocytes isolated from obese diabetic mice compared to normal littermates and in (b) adipocytes from non obese aged mice that develop glucose intolerance compared to young mice. Expression was not altered in the other tissues examined. Our data suggest that this novel gene could be involved in either development of glucose intolerance/type 2 diabetes or regulation of glucose metabolism in this disease state. Currently we are in the process of analyzing expression of this novel gene in other diabetic animal models and in adipocytes biopsies from obese and/or diabetic humans. Furthermore to establish its role in adipocyte physiology we are in the process of creating transgenic mice that specifically overexpress this gene in adipocytes. (2) We isolated a novel potential G-protein beta subunit from rat heart and muscle cDNA which contains signature sequences (WD-40 motifs) present in other G-protein beta subunits and signaling molecules. This clone is highly homologous to the most recently described G-protein beta subunit and is tentatively named G beta-6. G beta-6 is expressed in all insulin-sensitive tissues surveyed. The expression of G beta-6 is increased in Chinese hamster ovary (CHO) cells which overexpress the insulin receptors and are exposed to insulin compared to parental CHO cells. Likewise, overexpression of signaling deficient mutants of insulin receptor down regulates the expression of G beta-6. These data suggest that insulin receptor signaling up-regulates the expression of this G beta-6 indicating involvement in insulin signal transduction. We are currently in the process of isolating a full length clone for G beta-6. In addition using an antibody to G beta-6 that we have characterized, we are in the process of establishing associations of G beta-6 with other insulin receptor signaling molecules. This work received numerous awards including American Endocrine Society Travel Award (1996), Nathan Shock Poster Presentation Award (1996) and NIH FARE award (1997).
