The Control of Cholesterol Homeostasis: Regulation of HMG CoA Reductase
Cholesterol homeostasis within cells is regulated so as to provide adequate cholesterol without building up excessive stores. Two regulated pathways account for this cholesterol. The LDL receptor pathway mediates the uptake of cholesterol-containing lipoproteins from the plasma by receptor-mediated endocytosis. The endogenous cholesterol synthetic pathway which converts acetyl CoA to cholesterol via a multi-enzyme pathway is regulated by changes in the activity of HMG CoA reductase. Changes in the expression of HMG CoA reductase have been shown to affect the expression of LDL receptors both in cultured cells as well as in intact animals [1, 2]. To better understand the mechanisms that control cholesterol homeostasis, the means by which HMG CoA reductase is regulated have been studied. In cells, suppression of HMG CoA reductase activity by cholesterol is accomplished by at least two mechanisms:
decreased transcription of the HMG CoA reductase gene
enhanced degradation of the reductase protein.
KeywordsCholesterol Codon Superoxide Methionine Acetyl
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© Springer-Verlag Berlin Heidelberg 1986