Cholesterol hydroperoxides as substrates for cholesterol-metabolizing cytochrome?P450 enzymes and alternative sources of 25-hydroxycholesterol and other oxysterols.

ABSTRACT: The interaction of the primary autoxidation products of cholesterol, namely 25- and 20?-hydroperoxides, with the four principal cholesterol-metabolizing cytochrome?P450 enzymes is reported. Addition of cholesterol 25-hydroperoxide to the enzymes CYP27A1 and CYP11A1 induced well-defined spectral changes while generating 25-hydroxycholesterol as the major product. The 20?-hydroperoxides induced spectral shifts in CYP27A1 and CYP11A1 but glycol metabolites were detected only with CYP11A1. CYP7A1 and CYP46A1 failed to give metabolites with any of the hydroperoxides. A P450 hydroperoxide-shunt reaction is proposed, where the hydroperoxides serve as both donor for reduced oxygen and substrate. CYP27A1 was shown to mediate the reduction of cholesterol 25-hydroperoxide to 25-hydroxycholesterol, a role of potential significance for cholesterol-rich tissues with high oxidative stress. CYP27A1 may participate in the removal of harmful autoxidation products in these tissues, while providing a complementary source of 25-hydroxycholesterol, a modulator of immune cell function and mediator of viral cell entry.

SUBMITTER: van Lier JE 

PROVIDER: S-EPMC4578806 | biostudies-literature | 2015 Sep

REPOSITORIES: biostudies-literature