The proposed investigators deal with the mechanism by which oxysterol metabolites feedback to repress 3-hydroxy-3- methylglutaryl-CoA reductase (HMGR) and other genes of the cholesterogenic pathway. They focus upon the isolation, struc- ture and function of an oxysterol receptor which appears to mediate the inter action of oxysterols with the regulatory regions of these genes. Efforts to complete the isolation of the receptor from mouse L cells or mouse liver will involve conventional protein fractionation procedures with photoaffinity- labeled receptors and affinity chromatography with monoclonal and polyclonal antibodies or with an oxysterol affinity column. The amino acid sequence of the purified receptor will be determined and a portion of the corresponding DNA coding sequence synthesized to probe a mouse DNA library and to clone the receptor gene. Localization of the receptor in the nucleus or cytosol will be determined by enucleation of cells. Studied with the partially purified receptor will investigate conditions and mechanisms that lead to reversible and irreversible dissociation of heteromeric forms of the receptor. A factor(s) in cell cytosol that causes irreversible dissociation to the dimeric and trimeric receptor to a monomeric form will be identified. physical-chemical properties of the various forms of the receptor and their relative affinities for non-specific DNA and for oxysterol response elements from the promoters of regulated genes will be compared. The effect of the receptor in a HMGR transcriptional assay will be determined. Limited studies of invertebrates that do not synthesize sterols will be carried out to determine whether or not the receptor is present. Studies with mutant cell lines resistant to oxysterols will determine whether the mutations involve defects or deficiencies in the oxysterol receptor or the regulatory region of the HMGR gene. The results of these studies will increase our understanding of a regulatory system that is involved in cholesterol homeostasis and in cell growth, replication and differentiation.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Method to Extend Research in Time (MERIT) Award (R37)
Project #
5R37CA002758-35
Application #
3481587
Study Section
Metabolism Study Section (MET)
Project Start
1978-06-01
Project End
1992-11-30
Budget Start
1990-12-01
Budget End
1992-11-30
Support Year
35
Fiscal Year
1991
Total Cost
Indirect Cost
Name
Jackson Laboratory
Department
Type
DUNS #
042140483
City
Bar Harbor
State
ME
Country
United States
Zip Code
04609
Hallum 3rd, A V; Alberts, D S; Lippman, S M et al. (1995) Phase II study of 13-cis-retinoic acid plus interferon-alpha 2a in heavily pretreated squamous carcinoma of the cervix. Gynecol Oncol 56:382-6
Saucier, S E; Kandutsch, A A; Clark, D S et al. (1993) Hepatic uptake and metabolism of ingested 24-hydroxycholesterol and 24(S),25-epoxycholesterol. Biochim Biophys Acta 1166:115-23
Taylor, F R (1992) Correlation among oxysterol potencies in the regulation of the degradation of 3-hydroxy-3-methylglutaryl CoA reductase, the repression of 3-hydroxy-3-methylglutaryl CoA synthase and affinities for the oxysterol receptor. Biochem Biophys Res Commun 186:182-9
Taylor, F R; Shown, E P; Kandutsch, A A (1991) A proteolytic fragment of the oxysterol receptor which retains oxysterol binding activity. Arch Biochem Biophys 288:567-71
Saucier, S E; Kandutsch, A A; Gayen, A K et al. (1990) Oxygenation of desmosterol and cholesterol in cell cultures. J Lipid Res 31:2179-85
Schroeder, A C; Schultz, R M; Kopf, G S et al. (1990) Fetuin inhibits zona pellucida hardening and conversion of ZP2 to ZP2f during spontaneous mouse oocyte maturation in vitro in the absence of serum. Biol Reprod 43:891-7
Taylor, F R; Shown, E P; Thompson, E B et al. (1989) Purification, subunit structure, and DNA binding properties of the mouse oxysterol receptor. J Biol Chem 264:18433-9
Saucier, S E; Kandutsch, A A; Gayen, A K et al. (1989) Oxysterol regulators of 3-hydroxy-3-methylglutaryl-CoA reductase in liver. Effect of dietary cholesterol. J Biol Chem 264:6863-9
Taylor, F R; Kandutsch, A A (1989) Metabolism of 25-hydroxycholesterol in mammalian cell cultures. Side-chain scission to pregnenolone in mouse L929 fibroblasts. J Lipid Res 30:899-905
Schroepfer Jr, G J; Parish, E J; Tsuda, M et al. (1988) Inhibitors of sterol synthesis. Chemical syntheses, properties and effects of 4,4-dimethyl-15-oxygenated sterols on sterol synthesis and on 3-hydroxy-3-methylglutaryl coenzyme A reductase activity in cultured mammalian cells. Chem Phys Lipids 47:187-207

Showing the most recent 10 out of 18 publications