In situ accumulation of 3 beta-hydroxylanost-8-en-32-aldehyde in hepatocyte cultures. A putative regulator of 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity.
Biphasic modulation of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA reductase) has been demonstrated in primary hepatocyte cultures treated with the lanosterol 14 alpha-methyl demethylase inhibitor miconazole. At concentrations of the drug which lead to suppressed levels of reductase activity, the appearance of a polar, mevalonate-derived sterol is noted. Cochromatography of the identified sterol with 3 beta-hydroxylanost-8-en-32-aldehyde tentatively identified the metabolite as a lanosterol 14 alpha-methyl demethylation intermediate. Subsequent isolation and characterization of the metabolite by gas chromatography/mass spectroscopy confirmed this structural assignment. When the lanosterol 14 alpha-methyl demethylase-deficient mutant, AR45, was treated with authentic metabolite, a suppression of HMG-CoA reductase was observed. These results demonstrate that metabolism of the oxygenated biosynthetic intermediate is not required to suppress reductase activity. The results also strongly support the hypothesis that oxygenated 14 alpha-methyl demethylase intermediates are endogenously generated modulators of HMG-CoA reductase activity.
D000818:Animals; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D003577:Cytochrome P-450 Enzyme System; D008401:Gas Chromatography-Mass Spectrometry; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism*; D007810:Lanosterol / Q000031:analogs & derivatives* / Q000378:metabolism; D008297:Male; D008798:Mevalonic Acid / Q000378:metabolism; D008825:Miconazole / Q000494:pharmacology; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D010088:Oxidoreductases / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D058886:Sterol 14-Demethylase
D007810:Lanosterol; C032444:lanosten-3-ol-32-al; D008825:Miconazole; D003577:Cytochrome P-450 Enzyme System; D010088:Oxidoreductases; D006903:Hydroxymethylglutaryl CoA Reductases; D058886:Sterol 14-Demethylase; D008798:Mevalonic Acid