Faculty Collaboration Database

Vav protein guanine nucleotide exchange factor regulates CD36 protein-mediated macrophage foam cell formation via calcium and dynamin-dependent processes. J Biol Chem 2011 Oct 14;286(41):36011-36019

Date

08/26/2011

Pubmed ID

21865158

Pubmed Central ID

PMC3195569

DOI

10.1074/jbc.M111.265082

Scopus ID

2-s2.0-80053896976 (requires institutional sign-in at Scopus site)   41 Citations

Abstract

Atherosclerosis, a chronic inflammatory disease, results in part from the accumulation of modified lipoproteins in the arterial wall and formation of lipid-laden macrophages, known as "foam cells." Recently, we reported that CD36, a scavenger receptor, contributes to activation of Vav-family guanine nucleotide exchange factors by oxidatively modified LDL in macrophages. We also discovered that CD36-dependent uptake of oxidized LDL (oxLDL) in vitro and foam cell formation in vitro and in vivo was significantly reduced in macrophages deficient of Vav proteins. The goal of the present study was to identify the mechanisms by which Vav proteins regulate CD36-dependent foam cell formation. We now show that a Vav-dynamin signaling axis plays a critical role in generating calcium signals in mouse macrophages exposed to CD36-specific oxidized phospholipid ligands. Chelation of intracellular Ca(2+) or inhibition of phospholipase C-γ (PLC-γ) inhibited Vav activation (85 and 70%, respectively, compared with vehicle control) and reduced foam cell formation (approximately 75%). Knockdown of expression by siRNA or inhibition of GTPase activity of dynamin 2, a Vav-interacting protein involved in endocytic vesicle fission, significantly blocked oxLDL uptake and inhibited foam cell formation. Immunofluorescence microscopy studies showed that Vav1 and dynamin 2 colocalized with internalized oxLDL in macrophages and that activation and mobilization of dynamin 2 by oxLDL was impaired in vav null cells. These studies identified previously unknown components of the CD36 signaling pathway, demonstrating that Vav proteins regulate oxLDL uptake and foam cell formation via calcium- and dynamin 2-dependent processes and thus represent novel therapeutic targets for atherosclerosis.

Author List

Rahaman SO, Zhou G, Silverstein RL

Author

Roy L. Silverstein MD Professor in the Medicine department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Animals
Atherosclerosis
CD36 Antigens
Calcium
Calcium Signaling
Cells, Cultured
Dynamin II
Foam Cells
Gene Expression Regulation
Lipoproteins, LDL
Mice
Mice, Mutant Strains
Phospholipase C gamma
Proto-Oncogene Proteins c-vav
RNA, Small Interfering