Mitochondrial glycerol-3-phosphate acyltransferase-1 is essential in liver for the metabolism of excess acyl-CoAs.

Published

Journal Article

In vitro studies suggest that the mitochondrial glycerol-3-phosphate acyltransferase-1 (mtGPAT1) isoform catalyzes the initial and rate-controlling step in glycerolipid synthesis and aids in partitioning acyl-CoAs toward triacylglycerol synthesis and away from degradative pathways. To determine whether the absence of mtGPAT1 would increase oxidation of acyl-CoAs and restrict the development of hepatic steatosis, we fed wild type and mtGPAT1-/- mice a diet high in fat and sucrose (HH) for 4 months to induce the development of obesity and a fatty liver. Control mice were fed a diet low in fat and sucrose (LL). With the HH diet, absence of mtGPAT1 resulted in increased partitioning of acyl-CoAs toward oxidative pathways, demonstrated by 60% lower hepatic triacylglycerol content and 2-fold increases in plasma beta-hydroxybutyrate, acylcarnitines, and hepatic mRNA expression of mitochondrial HMG-CoA synthase. Despite the increase in fatty acid oxidation, liver acyl-CoA levels were 3-fold higher in the mtGPAT1-/- mice fed both diets. A lack of difference in CPT1 and FAS mRNA expression between genotypes suggested that the increased acyl-CoA content was not because of increased de novo synthesis, but instead, to an impaired ability to use long-chain acyl-CoAs derived from the diet, even when the dietary fat content was low. Hyperinsulinemia and reduced glucose tolerance on the HH diet was greater in the mtGPAT1-/- mice, which did not suppress the expression of the gluconeogenic genes glucose-6-phosphatase and phosphoenolpyruvate carboxykinase. This study demonstrates that mtGPAT1 is essential for normal acyl-CoA metabolism, and that the absence of hepatic mtGPAT1 results in the partitioning of fatty acids away from triacylglycerol synthesis and toward oxidation and ketogenesis.

Full Text

Duke Authors

Cited Authors

  • Hammond, LE; Neschen, S; Romanelli, AJ; Cline, GW; Ilkayeva, OR; Shulman, GI; Muoio, DM; Coleman, RA

Published Date

  • July 8, 2005

Published In

Volume / Issue

  • 280 / 27

Start / End Page

  • 25629 - 25636

PubMed ID

  • 15878874

Pubmed Central ID

  • 15878874

International Standard Serial Number (ISSN)

  • 0021-9258

Digital Object Identifier (DOI)

  • 10.1074/jbc.M503181200

Language

  • eng

Conference Location

  • United States