Purified cholesterol 7 alpha-hydroxylases (C7 alpha H) from human and rat liver microsomes, and from transformed Escherichia coli expression systems, were incubated with 0.3 mmol/L [gamma-P-32] adenosine triphosphate (ATP) in the presence and absence…
Bile acids activate a nuclear receptor, farnesoid X receptor (FXR), that induces bile salt export pump (BSEP) but inhibits cholesterol 7alpha-hydroxylase (CYP7A1) gene transcription in the liver. Guggulsterone, a plant sterol that lowers serum…
Cholesterol 7alpha-hydroxylase, the rate-limiting enzyme in the bile acid synthesis pathway, is down-regulated by taurocholate by way of negative feedback control at the level of gene transcription. The molecular basis of regulation of cholesterol…
Background/Aims: The decrease in cholesterol 7 alpha-hydroxylase induced by intraduodenal infusion of taurocholate in bile fistula vats may be indirect, i.e., mediated through release or absorption of an intestinal factor in response to the presence…
The present study examines the feedback control governing human cholesterol 7 alpha-hydroxylase mRNA expression in the human hepatoblastoma cell line, Hep G2. Glycochenodeoxycholate (GCDC) and glycodeoxycholate, hydrophobic bile salts, decreased…
This article is an invited report of a symposium sponsored by the Division for Drug Metabolism of the American Society for Pharmacology and Experimental Therapeutics held at Experimental Biology 2003 in San Diego, California, April 11 - 15, 2003.…
An overlapping binding site in the CYP7A1 promoter allows activation of FXR to override the stimulation by LXR alpha. Am J Physiol Gastrointest Liver Physiol 293: G817-G823, 2007. First published August 9, 2007; doi:10.1152/ajpgi.00209.2007.-The aim…
The transcription of the cholesterol 7 alpha-hydroxylase gene (CYP7A1) is greatly decreased in cholesterol-fed rabbits. To determine whether the molecular structure of the promoter is responsible for this downregulation, we cloned the rabbit CYP7A1…
This article is a report on a symposium sponsored by the American Society for Pharmacology and Experimental Therapeutics and held at the Experimental Biology 12 meeting in San Diego, CA. The presentations discussed the roles of a number of nuclear…
The current study examines regulation of CYP7B1, a DHEA 7 alpha-hydroxylase, by sex hormones. Transfection with estrogen receptor alpha and treatment with 17 P-estradiol in human embryonic kidney 293 cells significantly increased CYP7B1 catalytic…
The sterol 12alpha-hydroxylase (CYP8B1) is a key enzyme of the bile acid biosynthetic pathway. It regulates the composition of bile acids in bile, i.e. ratio between cholic acid (CA) and chenodeoxycholic acid (CDCA). In similarity with cholesterol…
Sterol 12alpha-hydroxylase (CYP8B1) is an obligatory enzyme for the synthesis of cholic acid and regulation of liver bile acid synthesis and intestine cholesterol absorption. The present study evaluates the roles for sterol regulatory element binding…
Taurocholate, a relatively hydrophobic bile salt, is a potent down-regulator of HMG-CoA reductase and cholesterol 7-alpha-hydroxylase (C7-alpha-H), the rate-determining enzymes of the cholesterol and bile acid biosynthetic pathways, respectively.…
In primary cultures of rat hepatocytes, transcription of the cholesterol 7 alpha-hydroxylase gene is induced synergistically by glucocorticoid and thyroid hormones. The objective of the present study was to evaluate the role of glucocorticoid and…
Cholesterol 7-alpha-hydroxylase catalyzes the rate-limiting step in the bile acid biosynthetic pathway. Regulation of this pathway is thought to occur solely as a result of a negative feedback control mechanism that is dependent upon the flux and…
The gene for cholesterol 7 alpha-hydroxylase (CYP7A1) contains a sequence at nt -149 to -118 that was found to play a large role in determining the overall transcriptional activity and regulation of the promoter. Hepatocyte nuclear factor 4 (HNF4)…
The cholesterol 7 alpha-hydroxylase gene (CYP7A) is transcriptionally regulated by a number of factors, including hormones, bile acids, and diurnal rhythm. Previous studies have identified a region from nucleotides (nt) -74 to -55 of the rat CYP7A…
