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Mol Cell Biol. 2009 Sep;29(17):4864-72. doi: 10.1128/MCB.00553-09. Epub 2009 Jun 29.

Sterol regulatory element binding protein 1a regulates hepatic fatty acid partitioning by activating acetyl coenzyme A carboxylase 2.

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1
Department of Molecular Biology and Biochemistry, University of California, Irvine, California 92697-3900, USA.

Erratum in

  • Mol Cell Biol. 2009 Nov;29(21):5974.

Abstract

We generated a line of mice in which sterol regulatory element binding protein 1a (SREBP-1a) was specifically inactivated by insertional mutagenesis. Homozygous mutant mice were completely viable despite expressing SREBP-1a mRNA below 5% of normal, and there were minimal effects on expression of either SREBP-1c or -2. Microarray expression studies in liver, where SREBP-1a mRNA is 1/10 the level of the highly similar SREBP-1c, demonstrated that only a few genes were affected. The only downregulated genes directly linked to lipid metabolism were Srebf1 (which encodes SREBP-1) and Acacb (which encodes acetyl coenzyme A [acetyl-CoA] carboxylase 2 [ACC2], a critical regulator of fatty acyl-CoA partitioning between cytosol and mitochondria). ACC2 regulation is particularly important during food restriction. Similar to Acacb knockout mice, SREBP-1a-deficient mice have lower hepatic triglycerides and higher serum ketones during fasting than wild-type mice. SREBP-1a and -1c have identical DNA binding and dimerization domains; thus, the failure of the more abundant SREBP-1c to substitute for activating hepatic ACC2 must relate to more efficient recruitment of transcriptional coactivators to the more potent SREBP-1a activation domain. Our chromatin immunoprecipitation results support this hypothesis.

PMID:
19564420
PMCID:
PMC2725716
DOI:
10.1128/MCB.00553-09
[Indexed for MEDLINE]
Free PMC Article
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