Abstract

Plasma membrane cholesterol-rich microdomains, lipid rafts and caveolae, mediate HDL reverse cholesterol transport, signaling, antibody recognition, and serve as entry portals for potential bioterror toxins, viruses, and parasites. While cholesterol is essential for lipid raft/caveolae function, almost nothing is known regarding distribution, structure, and regulation of cholesterol in lipid rafts or caveolae. Preliminary Data show sterol carrier protein-2 (SCP-2) binds caveolin-1 in vitro and in vivo, alters lipid raft/caveolae cholesterol domains, and inhibits HDL-mediated cholesterol efflux from cells rich in caveolin-1 (L-cell fibroblasts). In contrast, cultured primary hepatocytes (from wild-type, SCP-2 overexpressing, and SCP-2 gene targeted mice) provide a model for addressing cholesterol membrane dynamics in cells essentially deficient in caveolin-1, but rich in proteins that mediate cholesterol transport between plasma membrane and HDL (SRB1, P-gp, ABCA1). We now propose four specific aims.
Aim 1. Determine which proteins (SRB1, ABCA1, P-gp) mediating HDL-cholesterol efflux/uptake are present in plasma membrane lipid rafts versus caveolae, interactions between them, and interactions with caveolin-1.
Aim 2. Examine how SCP-2 interacts with caveolin-1, and whether SCP-2 binds lipid raft or caveolae proteins mediating HDL-cholesterol uptake/efflux (SRB 1, ABCA1, P-gp).
Aim 3. Resolve if SCP-2 expression alters cholesterol distribution, cholesterol dynamics, and structure in purified rafts and caveolae. SCP-2 level will be modified with SCP-2 overexpressing L-cell fibroblasts and primary cultured hepatocytes from SCP-2 overexpressed and gene-ablated mice.
Aim 4. In living cells, determine if SCP-2 expression alters cholesterol distribution, structure, and dynamics in lipid rafts or caveolae. Results will provide fundamental, mechanistic details of cholesterol organization and dynamics in lipid rafts, regulation by SCP-2, differential roles of rafts versus caveolae in mediating HDL-cholesterol uptake/efflux, and insights on potential intervention in metabolic disease, pathogen entry, and bioterror agents. ? ?

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
2R01GM031651-22
Application #
6730788
Study Section
Metabolism Study Section (MET)
Program Officer
Chin, Jean
Project Start
1997-10-01
Project End
2007-11-30
Budget Start
2003-12-01
Budget End
2004-11-30
Support Year
22
Fiscal Year
2004
Total Cost
$334,650
Indirect Cost

  Institution

Name
Texas Agrilife Research
Department
Physiology
Type
Schools of Earth Sciences/Natur
DUNS #
847205713
City
College Station
State
TX
Country
United States
Zip Code
77843

  Publications

McIntosh, Avery L; Atshaves, Barbara P; Landrock, Danilo et al. (2013) Liver fatty acid binding protein gene-ablation exacerbates weight gain in high-fat fed female mice. Lipids 48:435-48
Storey, Stephen M; McIntosh, Avery L; Huang, Huan et al. (2012) Intracellular cholesterol-binding proteins enhance HDL-mediated cholesterol uptake in cultured primary mouse hepatocytes. Am J Physiol Gastrointest Liver Physiol 302:G824-39
McIntosh, Avery L; Atshaves, Barbara P; Storey, Stephen M et al. (2012) Loss of liver FA binding protein significantly alters hepatocyte plasma membrane microdomains. J Lipid Res 53:467-80
Atshaves, Barbara P; McIntosh, Avery L; Storey, Stephen M et al. (2010) High dietary fat exacerbates weight gain and obesity in female liver fatty acid binding protein gene-ablated mice. Lipids 45:97-110
Landrock, Danilo; Atshaves, Barbara P; McIntosh, Avery L et al. (2010) Acyl-CoA binding protein gene ablation induces pre-implantation embryonic lethality in mice. Lipids 45:567-80
Schroeder, Friedhelm; Huang, Huan; McIntosh, Avery L et al. (2010) Caveolin, sterol carrier protein-2, membrane cholesterol-rich microdomains and intracellular cholesterol trafficking. Subcell Biochem 51:279-318
Storey, Stephen M; Atshaves, Barbara P; McIntosh, Avery L et al. (2010) Effect of sterol carrier protein-2 gene ablation on HDL-mediated cholesterol efflux from cultured primary mouse hepatocytes. Am J Physiol Gastrointest Liver Physiol 299:G244-54
Atshaves, Barbara P; Martin, Gregory G; Hostetler, Heather A et al. (2010) Liver fatty acid-binding protein and obesity. J Nutr Biochem 21:1015-32
Huang, Huan; McIntosh, Avery L; Atshaves, Barbara P et al. (2010) Use of dansyl-cholestanol as a probe of cholesterol behavior in membranes of living cells. J Lipid Res 51:1157-72
Zhou, Minglong; Widmer, R Jay; Xie, Wei et al. (2010) Effects of exercise training on cellular mechanisms of endothelial nitric oxide synthase regulation in coronary arteries after chronic occlusion. Am J Physiol Heart Circ Physiol 298:H1857-69

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