Dietary intake of excess fat or carbohydrate results in increased synthesis and storage of triacylglycerol (TAG). The long-chain fatty acids (FA) that contribute to TAG synthesis must be first converted to acyl-CoAs by long-chain acyl-CoA synthetase (ACSL). Because acyl-CoAs lie at a branch-point of storage and mitochondrial ?-oxidation, the fate of the acyl-CoAs formed may contribute to, or counteract, nutritional disorders related to increased TAG storage like obesity, fatty liver, atherosclerosis, and diabetes. We hypothesize that 1) ACSL1 is able to direct FA towards ?-oxidation in highly oxidative tissues because the enzyme interacts with carnitine acyltranferase to hand off its acyl-CoA product;2) that the function of ACSL1 differs in liver because at least 50% of the protein is present on the endoplasmic reticulum where it interacts with glycerolipid acyltransferases;and 3) that the mechanism for these differences lies both in the membrane association and phosphorylation status of ACSL1. Further, we propose that tissue use of glucose rather than FA as a fuel source is not without cost, and that the metabolic and functional problems arising from this use may be dangerous for organ function and insulin signaling. We further hypothesize, in keeping with the proposition that each ACSL directs FA towards a specific fate, that the ACSL4 isoform functions to regulate the entry of arachidonate into pathways of phospholipid synthesis versus eicosanoid formation. Our studies will address critical gaps in our knowledge about the metabolic fates of FA as substrates for complex lipid formation, as metabolic fuels, as precursors for eicosanoid signaling, as regulators of insulin action, and as transcription factor ligands.

Public Health Relevance

This project will enhance our understanding of insulin resistance, the metabolic syndrome, and cardiac and skeletal muscle fuel metabolism by determining the functions of two of the long-chain acyl-CoA synthetase isoforms in different tissues, by examining how they direct fatty acids towards different downstream pathways, and by investigating how abnormalities in ACSL function alters insulin signaling in cardiac and skeletal muscle.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK059935-12
Application #
8474746
Study Section
Integrative Nutrition and Metabolic Processes Study Section (INMP)
Program Officer
Pawlyk, Aaron
Project Start
2001-07-01
Project End
2016-05-31
Budget Start
2013-06-01
Budget End
2014-05-31
Support Year
12
Fiscal Year
2013
Total Cost
$301,447
Indirect Cost
$91,559
Name
University of North Carolina Chapel Hill
Department
Nutrition
Type
Schools of Public Health
DUNS #
608195277
City
Chapel Hill
State
NC
Country
United States
Zip Code
27599
Pascual, Florencia; Coleman, Rosalind A (2016) Fuel availability and fate in cardiac metabolism: A tale of two substrates. Biochim Biophys Acta 1860:1425-33
Alves-Bezerra, Michele; Klett, Eric L; De Paula, Iron F et al. (2016) Long-chain acyl-CoA synthetase 2 knockdown leads to decreased fatty acid oxidation in fat body and reduced reproductive capacity in the insect Rhodnius prolixus. Biochim Biophys Acta 1861:650-62
Li, Lei O; Grevengoed, Trisha J; Paul, David S et al. (2015) Compartmentalized acyl-CoA metabolism in skeletal muscle regulates systemic glucose homeostasis. Diabetes 64:23-35
Grevengoed, Trisha J; Martin, Sarah A; Katunga, Lalage et al. (2015) Acyl-CoA synthetase 1 deficiency alters cardiolipin species and impairs mitochondrial function. J Lipid Res 56:1572-82
Cooper, Daniel E; Young, Pamela A; Klett, Eric L et al. (2015) Physiological Consequences of Compartmentalized Acyl-CoA Metabolism. J Biol Chem 290:20023-31
Schisler, Jonathan C; Grevengoed, Trisha J; Pascual, Florencia et al. (2015) Cardiac energy dependence on glucose increases metabolites related to glutathione and activates metabolic genes controlled by mechanistic target of rapamycin. J Am Heart Assoc 4:
Grevengoed, Trisha J; Cooper, Daniel E; Young, Pamela A et al. (2015) Loss of long-chain acyl-CoA synthetase isoform 1 impairs cardiac autophagy and mitochondrial structure through mechanistic target of rapamycin complex 1 activation. FASEB J 29:4641-53
Liu, Yong; He, Yizhou; Jin, Aiwen et al. (2014) Ribosomal protein-Mdm2-p53 pathway coordinates nutrient stress with lipid metabolism by regulating MCD and promoting fatty acid oxidation. Proc Natl Acad Sci U S A 111:E2414-22
Grevengoed, Trisha J; Klett, Eric L; Coleman, Rosalind A (2014) Acyl-CoA metabolism and partitioning. Annu Rev Nutr 34:1-30
Paul, David S; Grevengoed, Trisha J; Pascual, Florencia et al. (2014) Deficiency of cardiac Acyl-CoA synthetase-1 induces diastolic dysfunction, but pathologic hypertrophy is reversed by rapamycin. Biochim Biophys Acta 1841:880-7

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