Obesity and its sequelae including diabetes are epidemic. Manipulating fat cells could lead to new therapies for obesity-associated disease. Peroxisome proliferator-activated receptors (PPARs) are involved in obesity and diabetes. One of these receptors, PPAR, is required for adipogenesis. Identification of endogenous PPAR ligands has been elusive. We have now identified an endogenous ligand for PPAR and developed an analogous strategy for identifying endogenous PPAR ligands. This work was predicated on the finding that inactivation of fatty acid synthase (FAS) in mouse liver produces a phenotype resembling PPAR deficiency that is rescued by pharmacologic activation of PPAR. Mass spectrometry techniques identified a lipid bound to PPAR that was FAS-dependent. This application focuses on obesity-resistant animals with FAS deficiency in adipose tissue, FASKOF (Fatty Acid Synthase KnockOut in Fat) mice. FAS-deficient embryonic fibroblasts have a phenotype resembling PPAR deficiency that is rescued by pharmacologic activation of PPAR. This project will test the hypothesis that in adipose tissue and its precursors, fatty acid synthase, an enzyme required for the process of de novo lipogenesis, mediates risk for obesity and metabolic disease in part by activating the nuclear receptor PPAR.
The specific aims are: 1. To determine if mice with FAS inactivation in adipose tissue (FASKOF mice) are protected from diet- induced and genetic obesity and if pharmacologic activation of PPAR reverses protection. 2. To determine if the presence of FAS is required for PPAR activation and the normal adipocyte differentiation process. 3. To use mass spectrometry analyses to identify potential endogenous PPAR ligands by comparing lipids bound to PPAR isolated from FASKOF (FAS-deficient) and control (FAS-replete) cells. This project has the potential to help clarify how endogenous ligands are generated for a nuclear receptor implicated in the modulation of adiposity, glucose metabolism and inflammation.
This application is relevant to public health and the mission of the NIH. Obesity shortens and diminishes the quality of life through its association with diabetes, heart disease and stroke, arthritis, sleep apnea, certain cancers, and other disorders. Identifying novel pathways for altering the function of fat cells has the potential to improve the metabolic milieu of obesity and treat obesity-associated diseases.
|Lodhi, Irfan J; Semenkovich, Clay F (2014) Peroxisomes: a nexus for lipid metabolism and cellular signaling. Cell Metab 19:380-92|
|Hsu, Fong-Fu; Lodhi, Irfan J; Turk, John et al. (2014) Structural distinction of diacyl-, alkylacyl, and alk-1-enylacyl glycerophosphocholines as [M - 15]? ions by multiple-stage linear ion-trap mass spectrometry with electrospray ionization. J Am Soc Mass Spectrom 25:1412-20|
|Wei, Xiaochao; Song, Haowei; Semenkovich, Clay F (2014) Insulin-regulated protein palmitoylation impacts endothelial cell function. Arterioscler Thromb Vasc Biol 34:346-54|
|Jensen-Urstad, Anne P L; Song, Haowei; Lodhi, Irfan J et al. (2013) Nutrient-dependent phosphorylation channels lipid synthesis to regulate PPAR*. J Lipid Res 54:1848-59|
|Spears, Larry D; Razani, Babak; Semenkovich, Clay F (2013) Interleukins and atherosclerosis: a dysfunctional family grows. Cell Metab 18:614-6|
|Funai, Katsuhiko; Song, Haowei; Yin, Li et al. (2013) Muscle lipogenesis balances insulin sensitivity and strength through calcium signaling. J Clin Invest 123:1229-40|
|Knobloch, Marlen; Braun, Simon M G; Zurkirchen, Luis et al. (2013) Metabolic control of adult neural stem cell activity by Fasn-dependent lipogenesis. Nature 493:226-30|
|Wei, Xiaochao; Yang, Zhen; Rey, Federico E et al. (2012) Fatty acid synthase modulates intestinal barrier function through palmitoylation of mucin 2. Cell Host Microbe 11:140-52|
|Cheverud, James M; Lawson, Heather A; Fawcett, Gloria L et al. (2011) Diet-dependent genetic and genomic imprinting effects on obesity in mice. Obesity (Silver Spring) 19:160-70|
|Lawson, Heather A; Lee, Arthur; Fawcett, Gloria L et al. (2011) The importance of context to the genetic architecture of diabetes-related traits is revealed in a genome-wide scan of a LG/J ýý SM/J murine model. Mamm Genome 22:197-208|
Showing the most recent 10 out of 14 publications