Early in the pathogenesis of atherosclerosis, aggregated, oxidized lipoprotein particles become attached to proteins in the subendothelial matrix of the affected arteries. Monocytes (Mos) that traverse the overlying endothelium come into contact with these matrix-bound lipoprotein particles, engulf them, and eventually take up large amounts of lipid, developing into lipid-engorged macrophage foam cells, which promote further growth of the atherosclerotic plaque. We hypothesize that alterations in the plasma membrane cholesterol levels in Mos and macrophages caused by interactions with these matrix-bound lipoproteins may be partially responsible for lesion growth. Based on our preliminary studies, we postulate that retained and aggregated lipoproteins alter actin dynamics in Mos and macrophages in the subendothelial space, and therefore inhibit the migration and phagocytic function of these cells. This may promote the retention of cells in the tissue and thus the growth of atherosclerotic plaques.
The specific aims of this grant are designed to test this hypothesis. Numerous studies have investigated the effects of reducing membrane cholesterol levels on cellular functions, but far fewer have looked at the effects of the potentially more physiologically significant event of increasing membrane cholesterol levels. Our preliminary data indicate that overloading a Mo's plasma membrane with cholesterol decreases its migration rate in a three dimensional (3D) collagen gel. Similarly, our studies with neutrophils showed that cholesterol depletion inhibited Rac GTPase-mediated actin reorganization and migration. We propose to first quantify the extent to which stimulated actin reorganization in Mos and macrophages is sensitive to raising or lowering membrane cholesterol levels, and then we will study how these changes affect the actin-dependent functions of migration and phagocytosis. Next, we will directly test the idea that effects on migration and phagocytic function can be attributed to disruption of activation and/or targeting of Rho GTPases (i.e. Rho, Rac, and Cdc42). Initially we will use pharmacological means to alter membrane cholesterol, and later we will use progressively more physiological cholesterol modulating scenarios from isolated lipoproteins to matrix-embedded lipoproteins that mimic an atherogenic environment.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Program Projects (P01)
Project #
5P01HL072942-03
Application #
7061260
Study Section
Special Emphasis Panel (ZHL1)
Project Start
Project End
Budget Start
2005-04-01
Budget End
2006-03-31
Support Year
3
Fiscal Year
2005
Total Cost
$232,949
Indirect Cost
Name
Weill Medical College of Cornell University
Department
Type
DUNS #
060217502
City
New York
State
NY
Country
United States
Zip Code
10065
Kennedy, David J; Chen, Yiliang; Huang, Wenxin et al. (2013) CD36 and Na/K-ATPase-?1 form a proinflammatory signaling loop in kidney. Hypertension 61:216-24
Butler, Jason M; Kobayashi, Hideki; Rafii, Shahin (2010) Instructive role of the vascular niche in promoting tumour growth and tissue repair by angiocrine factors. Nat Rev Cancer 10:138-46
Nakaya, Hideaki; Summers, Barbara D; Nicholson, Andrew C et al. (2009) Atherosclerosis in LDLR-knockout mice is inhibited, but not reversed, by the PPARgamma ligand pioglitazone. Am J Pathol 174:2007-14
Hooper, Andrea T; Shmelkov, Sergey V; Gupta, Sunny et al. (2009) Angiomodulin is a specific marker of vasculature and regulates vascular endothelial growth factor-A-dependent neoangiogenesis. Circ Res 105:201-8
Haka, Abigail S; Grosheva, Inna; Chiang, Ethan et al. (2009) Macrophages create an acidic extracellular hydrolytic compartment to digest aggregated lipoproteins. Mol Biol Cell 20:4932-40
Kopp, Hans-Georg; Hooper, Andrea T; Avecilla, Scott T et al. (2009) Functional heterogeneity of the bone marrow vascular niche. Ann N Y Acad Sci 1176:47-54
Hooper, Andrea T; Butler, Jason M; Nolan, Daniel J et al. (2009) Engraftment and reconstitution of hematopoiesis is dependent on VEGFR2-mediated regeneration of sinusoidal endothelial cells. Cell Stem Cell 4:263-74
Muller, William A; Luscinskas, F William (2008) Assays of transendothelial migration in vitro. Methods Enzymol 443:155-76
Zhou, Xiaoye; He, Wei; Huang, Zhiping et al. (2008) Genetic deletion of low density lipoprotein receptor impairs sterol-induced mouse macrophage ABCA1 expression. A new SREBP1-dependent mechanism. J Biol Chem 283:2129-38
Lamon, Brian D; Hajjar, David P (2008) Inflammation at the molecular interface of atherogenesis: an anthropological journey. Am J Pathol 173:1253-64

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