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 (MARK) 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 stressorsto manipulate lipogenesis in adipocytes to dissect mechanisms of regulation. We hypothesize that critical signals (ROS or ROS-independent) are generatedas 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 integratedapplication 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.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK059261-07
Application #
7333302
Study Section
Cellular Aspects of Diabetes and Obesity Study Section (CADO)
Program Officer
Haft, Carol R
Project Start
2000-06-01
Project End
2010-12-31
Budget Start
2008-01-01
Budget End
2008-12-31
Support Year
7
Fiscal Year
2008
Total Cost
$281,897
Indirect Cost
Name
Boston Medical Center
Department
Type
DUNS #
005492160
City
Boston
State
MA
Country
United States
Zip Code
02118
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