Expression of SREBP-1c requires SREBP-2-mediated generation of a sterol ligand for LXR in livers of mice
The synthesis of cholesterol and fatty acids (FA) in liver is independently regulated by SREBP-2 and SREBP-1c, respectively. Here we genetically deleted Srebf-2 from hepatocytes and confirmed that SREBP-2 regulates all genes involved in cholesterol biosynthesis, the LDL receptor, and PCSK9; a secreted protein that degrades LDL receptors in liver. Surprisingly, we found that elimination of Srebf-2 in hepatocytes of mice also markedly reduced SREBP-1c and the expression of all genes involved in FA and triglyceride synthesis that are normally regulated by SREBP-1c. The nuclear receptor LXR is necessary for Srebf-1c transcription. The deletion of Srebf-2 and subsequent lower sterol synthesis in hepatocytes eliminated the production of an endogenous sterol ligand required for LXR activity and SREBP-1c expression. These studies demonstrate that cholesterol and FA synthesis in hepatocytes are coupled and that flux through the cholesterol biosynthetic pathway is required for maximal SREBP-1c expression and high rates of FA synthesis.
Article and author information
National Institutes of Health (HL-20948)
- Jay D Horton
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Animal experimentation: All animal experiments were performed with approval of the Institutional Animal Care and Research Advisory Committee at UT Southwestern.
- Peter Tontonoz, University of California, Los Angeles, United States
- Received: January 9, 2017
- Accepted: February 26, 2017
- Accepted Manuscript published: February 28, 2017 (version 1)
- Accepted Manuscript updated: March 6, 2017 (version 2)
- Version of Record published: March 13, 2017 (version 3)
© 2017, Rong et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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