Received for publication December 5, 2005.
Revised January 16, 2006.
Accepted for publication January 18, 2006.

Cholesterol-metabolizing cytochromes P450

Abstract

By catalyzing the first steps in different pathways of cholesterol degradation, cytochromes P450 (P450s or CYPs) 7A1, 27A1, 11A1, and 46A1 play key roles in cholesterol homeostasis. CYP7A1 is a microsomal liver-specific enzyme that converts cholesterol to 7-hydroxycholesterol. CYP27A1 is a ubiquitously expressed mitochondrial P450 that metabolizes cholesterol to 27-hydroxycholesterol. CYP11A1 also resides in mitochondria but is expressed mainly in steroidogenic tissues where it catalyses the conversion of cholesterol to pregnenolone. Finally, CYP46A1 is a brain-selective microsomal monoxygenase producing 24S-hydroxycholesterol from cholesterol. Catalytic efficiencies of cholesterol-metabolizing P450s vary significantly and likely reflect physiological requirements of different organs for the rate of cholesterol turnover. P450s 7A1, 27A1, 11A1, and 46A1 represent a unique system for elucidation of how different enzymes have adapted to fit their specific roles in cholesterol elimination. Studies of cholesterol-metabolizing P450s suggest that their activities could be modulated post-translationally and that they should also be considered as targets for regulation of cholesterol homeostasis.

Key words: cholesterol, cytochrome P450, cytochrome P450 function, extrahepatic cytochrome P450, human CYP enzymes, membrane-protein interactions, structure-activity relationships

This article has been cited by other articles:

				N. Mast, M. A. White, I. Bjorkhem, E. F. Johnson, C. D. Stout, and I. A. Pikuleva Crystal structures of substrate-bound and substrate-free cytochrome P450 46A1, the principal cholesterol hydroxylase in the brain PNAS, July 15, 2008; 105(28): 9546 - 9551. [Abstract] [Full Text] [PDF]