Associate Provost for Research Boston University Medical Campus
NIDDK - National Institute of Diabetes & Digestive & Kidney Diseases	Research Resources

Abstract

Abstract: DESCRIPTION (provided by applicant): Obesity is a major health problem that predisposes to type 2 diabetes and other serious conditions. A more complete understanding of how fat synthesis is regulated in adipocytes is critical to guide rational development of new approaches for treating obesity and its complications. In the last grant period, we demonstrated that medium-chain fatty acids (octanoate) stimulate beta-oxidation and inhibit triglyceride synthesis in adipocytes, mimicking some of the metabolic effects of fasting. Analogous anti-lipogenic effects have been found in adipocytes treated with TNFalpha. We demonstrated that the three stressors, fasting in vivo, octanoate, and TNFalpha in vitro, induce many of the same cellular responses. These include increased generation of reactive oxidative species (ROS), activation of MAP-kinases (MAPK) and AMP-activated protein kinase (AMPK), and decreased expression of the nuclear transcription factor PPARgamma and associated lipogenic genes. In light of these findings, we plan to use these three stressors to manipulate lipogenesis in adipocytes to dissect mechanisms of regulation. We hypothesize that critical signals (ROS or ROS-independent) are generated as a result of increased beta-oxidation. These signaling molecules activate stress-responsive kinases, which inactivate PPARgamma, attenuating expression of genes necessary for fat synthesis. To test this hypothesis, we propose the following specific aims: (1) to determine whether ROS is crucial for regulation of lipogenesis; (2) to test if changes in beta-oxidation generate critical signals that cause inactivation of PPARgamma; and (3) to determine if PPARgamma is the point at which signals converge that control stress-induced anti-lipogenic effects, what is the mechanism of PPARgamma inactivation, and which metabolic genes are most sensitive to the stress manipulation. Each aim will be addressed with comprehensive and integrated application of cell biology and molecular biology in combination with metabolic and biochemical approaches, using culture murine and human adipocytes as well as rodent models. Together, these studies will provide new insights into the stress-induced regulation of lipogenesis in adipocytes, a potentially important avenue for modulating energy balance.

Thesaurus Terms:
adipocyte, free radical oxygen, lipid metabolism, lipolysis, obesity, oxidation, physiologic stressor, short chain fatty acid
bioenergetics, fasting, gene induction /repression, mitogen activated protein kinase, nutrient intake activity, peroxisome proliferator activated receptor, transcription factor, triglyceride, tumor necrosis factor alpha
human tissue, laboratory rat, northern blotting, nuclear magnetic resonance spectroscopy, tissue /cell culture

Institution:	BOSTON MEDICAL CENTER
	ONE BOSTON MEDICAL CENTER PLACE
	BOSTON, MA 02118
Fiscal Year:	2006
Department:
Project Start:	01-JUN-2000
Project End:	31-DEC-2010
ICD:	NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
IRG:	CADO