The long range objective of the proposed research is to gain a complete understanding of the role of oxygenated sterols (oxysterols) in the complex mechanisms by which cholesterol metabolism is regulated. Two key unresolved aspects of the putative participation of oxysterols in this important area of biomedical research will be investigated. First, the role of oxysterols will be more precisely defined by correlating both their positive and negative effects in different cellular compartments with changes in activities of key enzymes of cholesterol metabolism as a function of time. This will be accomplished by studies of the effects of a cholesterol-enriched diet, and cessation thereof, on the concentrations of oxysterols in rat liver subcellular fractions in relation to the corollary effects on 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, a rate limiting enzyme of cholesterol synthesis, as an index for negative response, and on cholesterol 7 alpha-hydroxylase, the rate limiting enzyme of bile acid synthesis, as an index for positive response. In addition, the effects of mevalonic acid, as a precursor of sterols and oxysterols in vivo, on these same factors, will be investigated. Second, the hypothesis will be explored that oxysterols, specifically those identified as potential signal molecules in rat liver, are associated with specific proteins in 1) the cytosol, and 2) the nucleus, by identifying endogenously bound oxysterols in protein fractions separated by isoelectric focusing. Any putative receptor proteins thus identified will be isolated, purified, and characterized. Initial exploration of the possible significance of the fact that a major portion of the intracellular oxysterols exist in esterified form also will be conducted. All of these planned experiments have as their fundamental goal a better understanding of the centrally important issue of how cholesterol metabolism is regulated. Such understanding will contribute to achieving the ability either to prevent or reverse atherosclerosis. In addition, detailed knowledge of how cholesterol metabolism is regulated will be important in efforts to prevent or control other pathological conditions, such as cholesterol gallstone disease or malignancies.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL052069-03
Application #
2430736
Study Section
Metabolism Study Section (MET)
Project Start
1995-07-01
Project End
1999-05-31
Budget Start
1997-06-01
Budget End
1998-05-31
Support Year
3
Fiscal Year
1997
Total Cost
Indirect Cost
Name
Dartmouth College
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
041027822
City
Hanover
State
NH
Country
United States
Zip Code
03755
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Shenoy, Sarita D; Spencer, Thomas A; Mercer-Haines, Nancy A et al. (2004) Induction of CYP3A by 2,3-oxidosqualene:lanosterol cyclase inhibitors is mediated by an endogenous squalene metabolite in primary cultured rat hepatocytes. Mol Pharmacol 65:1302-12
Erickson, Sandra K; Lear, Steven R; Deane, Sean et al. (2003) Hypercholesterolemia and changes in lipid and bile acid metabolism in male and female cyp7A1-deficient mice. J Lipid Res 44:1001-9
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Spencer, T A; Li, D; Russel, J S et al. (2001) Pharmacophore analysis of the nuclear oxysterol receptor LXRalpha. J Med Chem 44:886-97
Li, D; Spencer, T A (2000) Synthesis of 7alpha-hydroxy derivatives of regulatory oxysterols. Steroids 65:529-35
Spencer, T A; Li, D; Russel, J S et al. (2000) Further studies on the synthesis of 24(S),25-epoxycholesterol. A new, efficient preparation of desmosterol. J Org Chem 65:1919-23
Massimi, M; Lear, S R; Williams, D L et al. (1999) Differential expression of apolipoprotein E messenger RNA within the rat liver lobule determined by in situ hybridization. Hepatology 29:1549-55

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