REV-ERBα Regulates CYP7A1 Through Repression of Liver Receptor Homolog-1

Dec 15, 2017Drug metabolism and disposition: the biological fate of chemicals

REV-ERBα controls CYP7A1 by blocking a liver hormone receptor

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Abstract

GSK2945 treatment increased hepatic cholesterol 7-hydroxylase (Cyp7a1) level and lowered plasma cholesterol in wild-type mice.

REV-ERB regulates cholesterol 7-hydroxylase (CYP7A1) and bile acid synthesis.
The compound GSK2945 acts as a specific antagonist to REV-ERB.
GSK2945 treatment resulted in reduced plasma and liver cholesterol levels in hypercholesterolemic mice.
Increased expression of Cyp7a1/CYP7A1 was observed in both mouse and human primary liver cells after GSK2945 treatment.
Lrh-1 was identified as a direct target gene of REV-ERB and is associated with the regulation of Cyp7a1.
Conditional deletion of Lrh-1 in the liver diminished the effects of REV-ERB on cholesterol metabolism.

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Nuclear heme receptor reverse erythroblastosis virus (REV-ERB)(a transcriptional repressor) is known to regulate cholesterol 7-hydroxylase (CYP7A1) and bile acid synthesis. However, the mechanism for REV-ERBregulation of CYP7A1 remains elusive. Here, we investigate the role of LRH-1 in REV-ERBregulation of CYP7A1 and cholesterol metabolism. We first characterized the tertiary amine-(4-chloro-2-methylbenzyl)--(4-chlorobenzyl)-1-(5-nitrothiophen-2-yl)methanamine (GSK2945) as a highly specific Rev-erb/REV-ERBantagonist using cell-based assays and confirmed expression of Rev-erbin mouse liver. GSK2945 treatment increased hepatic mouse cholesterol 7-hydroxylase (Cyp7a1) level and lowered plasma cholesterol in wild-type mice. Likewise, the compound increased the expression and microsomal activity of Cyp7a1 in hypercholesterolemic mice. This coincided with reduced plasma and liver cholesterol and enhanced production of bile acids. Increased levels of Cyp7a1/CYP7A1 were also found in mouse and human primary hepatocytes after GSK2945 treatment. In these experiments, we observed parallel increases in Lrh-1/LRH-1 (a known hepatic activator of Cyp7a1/CYP7A1) mRNA and protein. Luciferase reporter, mobility shift, and chromatin immunoprecipitation assays revealed that Lrh-1/LRH-1 was a direct Rev-erb/REV-ERBtarget gene. Furthermore, conditional deletion of Lrh-1 in the liver abrogated the regulatory effects of Rev-erbon Cyp7a1 and cholesterol metabolism in mice. In conclusion, Rev-erbregulates Cyp7a1 and cholesterol metabolism through its repression of the Lrh-1 receptor. Targeting the REV-ERB/LRH-1 axis may represent a novel approach for management of cholesterol-related diseases. α α α α N N α α α α α α α α α

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REV-ERBα Regulates CYP7A1 Through Repression of Liver Receptor Homolog-1

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