Normal cells control their cholesterol content within narrow limits. If cholesterol uptake increases, cholesterol efflux is also increased to keep cell cholesterol content the same. If this response is inhibited, free and esterified cholesterol accumulate in the cell. Foam cell formation reflects a failure of this regulatory pathway. The molecular basis of this reflexive cholesterol unloading and its regulation will be determined. We recently observed that caveolae, which are cholesterol-rich cell surface microdomains, are the terminus of the cholesterol efflux pathway to high density lipoprotein. The presence of caveolae at the cell surface is recognized to depend on caveolin, a 22kDa cholesterol-binding protein.
Four Specific Aims deal with different aspects of the molecular and cell biology of caveolae related to cholesterol transport and efflux. In the first Specific Aim, the mechanism of induction of caveolin mRNA in response to cholesterol loading by low density lipoprotein will be determined. In the second Specific Aim, human lymphoid cells which lack endogenous caveolin will be stably transfected with human caveolin cDNA. Its effects on the ability of these cells to regulate their cholesterol content will be determined. In the third Specific Aim, the intracellular lipid vesicles that carry cholesterol to the caveolae will be fully characterized, as will the cytoplasmic factors required for cholesterol transport. In the last Specific Aim, the identity of a factor, possibly related to cellubrevin, which targets intracellular cholesterol to the cell surface caveolae, will be established. These studies will provide novel basic information on the biology of cellular cholesterol homeostasis. They will also identify new targets for intervention in promoting the unloading of cholesterol-filled cells.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL057976-04
Application #
6184367
Study Section
Pathology A Study Section (PTHA)
Project Start
1997-04-01
Project End
2001-03-31
Budget Start
2000-04-01
Budget End
2001-03-31
Support Year
4
Fiscal Year
2000
Total Cost
$356,621
Indirect Cost
Name
University of California San Francisco
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
073133571
City
San Francisco
State
CA
Country
United States
Zip Code
94143
Chau, Phuonglan; Fielding, Phoebe E; Fielding, Christopher J (2007) Bone morphogenetic protein-1 (BMP-1) cleaves human proapolipoprotein A1 and regulates its activation for lipid binding. Biochemistry 46:8445-50
Chau, Phuonglan; Nakamura, Yasushi; Fielding, Christopher J et al. (2006) Mechanism of prebeta-HDL formation and activation. Biochemistry 45:3981-7
Huuskonen, Jarkko; Vishnu, Meeta; Fielding, Phoebe E et al. (2005) Activation of ATP-binding cassette transporter A1 transcription by chromatin remodeling complex. Arterioscler Thromb Vasc Biol 25:1180-5
Huuskonen, Jarkko; Vishnu, Meeta; Pullinger, Clive R et al. (2004) Regulation of ATP-binding cassette transporter A1 transcription by thyroid hormone receptor. Biochemistry 43:1626-32
Nakamura, Yasushi; Kotite, Leila; Gan, Yonghong et al. (2004) Molecular mechanism of reverse cholesterol transport: reaction of pre-beta-migrating high-density lipoprotein with plasma lecithin/cholesterol acyltransferase. Biochemistry 43:14811-20
Huuskonen, Jarkko; Fielding, Phoebe E; Fielding, Christopher J (2004) Role of p160 coactivator complex in the activation of liver X receptor. Arterioscler Thromb Vasc Biol 24:703-8
Fielding, Phoebe E; Chau, Phuonglan; Liu, Dong et al. (2004) Mechanism of platelet-derived growth factor-dependent caveolin-1 phosphorylation: relationship to sterol binding and the role of serine-80. Biochemistry 43:2578-86
Fielding, C J; Fielding, P E (2004) Membrane cholesterol and the regulation of signal transduction. Biochem Soc Trans 32:65-9
Spencer, Thomas A; Wang, Pingzhen; Li, Dansu et al. (2004) Benzophenone-containing cholesterol surrogates: synthesis and biological evaluation. J Lipid Res 45:1510-8
Zheng, Yong-Hui; Plemenitas, Ana; Fielding, Christopher J et al. (2003) Nef increases the synthesis of and transports cholesterol to lipid rafts and HIV-1 progeny virions. Proc Natl Acad Sci U S A 100:8460-5

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