Abstract
Microsomal preparations from normal human skin fibroblasts were used to investigate the role of free cholesterol in the endoplasmic reticulum in the control of cholesterol biosynthesis by regulation of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (NADPH) [(S)-mevalonate:NADP+ oxidoreductase (CoA-acylating), EC 1.1.1.34]. Controlled changes in the cholesterol/phospholipid ratio of microsomes were introduced either in intact cells by incubating fibroblast cultures with whole serum or lipoprotein-deficient serum or by enrichment or depletion of cholesterol in microsomal preparations by incubating microsomes with cholesterol-rich or cholesterol-poor egg phosphatidylcholine unilamellar vesicles. Cholesterol enrichment resulted in suppression of reductase activity and increased ESR order parameters for 12-nitroxystearate in the microsomal preparations. Conversely, cholesterol depletion caused an activation of reductase and a decrease in order parameter. Enrichment of microsomal preparations with a "nonfluid" lipid, dipalmitoyl phosphatidylcholine, also suppressed enzyme activity and increased membrane order. The effect was reversed by subsequent enrichment of the microsomes with fluid egg phosphatidylcholine. Our findings suggest that cholesterol may regulate its own biosynthesis, at least in part, by suppression of hydroxymethylglutaryl-CoA reductase mediated through changes in membrane fluidity as measured by ESR order parameter.
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Selected References
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- BLIGH E. G., DYER W. J. A rapid method of total lipid extraction and purification. Can J Biochem Physiol. 1959 Aug;37(8):911–917. doi: 10.1139/o59-099. [DOI] [PubMed] [Google Scholar]
- BUCHER N. L., OVERATH P., LYNEN F. beta-Hydroxy-beta-methyl-glutaryl coenzyme A reductase, cleavage and condensing enzymes in relation to cholesterol formation in rat liver. Biochim Biophys Acta. 1960 Jun 3;40:491–501. doi: 10.1016/0006-3002(60)91390-1. [DOI] [PubMed] [Google Scholar]
- Brown M. S., Dana S. E., Goldstein J. L. Regulation of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity in human fibroblasts by lipoproteins. Proc Natl Acad Sci U S A. 1973 Jul;70(7):2162–2166. doi: 10.1073/pnas.70.7.2162. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Brown M. S., Goldstein J. L. Multivalent feedback regulation of HMG CoA reductase, a control mechanism coordinating isoprenoid synthesis and cell growth. J Lipid Res. 1980 Jul;21(5):505–517. [PubMed] [Google Scholar]
- Chalvardjian A., Rudnicki E. Determination of lipid phosphorus in the nanomolar range. Anal Biochem. 1970 Jul;36(1):225–226. doi: 10.1016/0003-2697(70)90352-0. [DOI] [PubMed] [Google Scholar]
- Gibson D. M., Ingebritsen T. S. Reversible modulation of liver hydroxymethylglutaryl CoA reductase. Life Sci. 1978 Dec 31;23(27-28):2649–2664. doi: 10.1016/0024-3205(78)90644-6. [DOI] [PubMed] [Google Scholar]
- Gil G., Faust J. R., Chin D. J., Goldstein J. L., Brown M. S. Membrane-bound domain of HMG CoA reductase is required for sterol-enhanced degradation of the enzyme. Cell. 1985 May;41(1):249–258. doi: 10.1016/0092-8674(85)90078-9. [DOI] [PubMed] [Google Scholar]
- Hardgrave J. E., Heller R. A., Herrera M. G., Scallen T. J. Immunotitration of 3-hydroxy-3-methylglutaryl-coenzyme A reductase in various physiological states. Proc Natl Acad Sci U S A. 1979 Aug;76(8):3834–3838. doi: 10.1073/pnas.76.8.3834. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hashimoto S., Drevon C. A., Weinstein D. B., Bernett J. S., Dayton S., Steinberg D. Activity of acyl-CoA: cholesterol acyltransferase and 3-hydroxy-3-methylglutaryl-CoA reductase in subfractions of hepatic microsomes enriched with cholesterol. Biochim Biophys Acta. 1983 Nov 29;754(2):126–133. doi: 10.1016/0005-2760(83)90153-4. [DOI] [PubMed] [Google Scholar]
- Hatch F. T. Practical methods for plasma lipoprotein analysis. Adv Lipid Res. 1968;6:1–68. [PubMed] [Google Scholar]
- LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
- Landsberger F. R., Lenard J., Paxton J., Compans R. W. Spin-labeled electron spin resonance study of the lipid-containing membrane of influenza virus. Proc Natl Acad Sci U S A. 1971 Oct;68(10):2579–2583. doi: 10.1073/pnas.68.10.2579. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Philipp B. W., Shapiro D. J. Improved methods for the assay and activation of 3-hydroxy-3-methylglutaryl coenzyme A reductase. J Lipid Res. 1979 Jul;20(5):588–593. [PubMed] [Google Scholar]
- Richert L., Castagna M., Beck J. P., Rong S., Luu B., Ourisson G. Growth-rate-related and hydroxysterol-induced changes in membrane fluidity of cultured hepatoma cells: correlation with 3-hydroxy-3-methyl glutaryl CoA reductase activity. Biochem Biophys Res Commun. 1984 Apr 16;120(1):192–198. doi: 10.1016/0006-291x(84)91432-3. [DOI] [PubMed] [Google Scholar]
- Rodwell V. W., Nordstrom J. L., Mitschelen J. J. Regulation of HMG-CoA reductase. Adv Lipid Res. 1976;14:1–74. doi: 10.1016/b978-0-12-024914-5.50008-5. [DOI] [PubMed] [Google Scholar]
- Rudel L. L., Morris M. D. Determination of cholesterol using o-phthalaldehyde. J Lipid Res. 1973 May;14(3):364–366. [PubMed] [Google Scholar]
- Schreier-Muccillo S., Marsh D., Dugas H., Schneider H., Smith C. P. A spin probe study of the influence of cholesterol on motion and orientation of phospholipids in oriented multibilayers and vesicles. Chem Phys Lipids. 1973 Jan;10(1):11–27. doi: 10.1016/0009-3084(73)90037-6. [DOI] [PubMed] [Google Scholar]
- Venkatesan S., Mitropoulos K. A. 3-Hydroxy-3-methylglutaryl-coenzyme A reductase. The difference in the mechanism of the in vitro modulation by phosphorylation and dephosphorylation to modulation of enzyme activity by non-esterified cholesterol. Biochim Biophys Acta. 1982 Mar 12;710(3):446–455. doi: 10.1016/0005-2760(82)90128-x. [DOI] [PubMed] [Google Scholar]
- van Heusden G. P., Wirtz K. W. Hydroxymethylglutaryl CoA reductase and the modulation of microsomal cholesterol content by the nonspecific lipid transfer protein. J Lipid Res. 1984 Jan;25(1):27–32. [PubMed] [Google Scholar]
