Incubation of monolayers of cultured human fibroblasts with oxygenated sterols (25 hydroxycholesterol, 7 ketocholesterol, or 6 ketocholestanol) markedly enhanced the rate at which the cells esterified their endogenous cholesterol and produced an increase in the cellular content of cholesterol esters. The enhanced esterification capacity was associated with an increase in the activity of a membrane bound fatty acyl CoA: cholesteryl acyltransferase. Incubation of cells of 5 hr and 5 μg/ml of 25 hydroxycholesterol produced an 8 fold increase in the specific activity of this enzyme when assayed in cell free extracts. Sine the oxygenated sterols that elevated the activity of fatty acyl CoA:cholesteryl acyltransferase also suppressed the activity of 3 hydroxy 3 methylglutaryl coenzyme A reductase, the data suggest that the processes of cholesterol ester formation and cholesterol synthesis in human fibroblasts are regulated in a reciprocal manner by coordinate changes in the activities of these two membrane bound enzymes.
|Original language||English (US)|
|Number of pages||3|
|Journal||Journal of Biological Chemistry|
|State||Published - Dec 1 1975|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology