CD36 modulates migration of mouse and human macrophages in response to oxidized LDL and may contribute to macrophage trapping in the arterial intima

Abstract

The trapping of lipid-laden macrophages in the arterial intima is a critical but reversible step in atherogenesis. However, the mechanism by which this occurs is not clearly defined. Here, we tested in mice the hypothesis that CD36, a class B scavenger receptor expressed on macrophages, has a role in this process. Using both in vivo and in vitro migration assays, we found that oxidized LDL (oxLDL), but not native LDL, inhibited migration of WT mouse macrophages but not CD36-deficient cells. We further observed a crucial role for CD36 in modulating the in vitro migratory response of human peripheral blood monocyte-derived macrophages to oxLDL. oxLDL also induced rapid spreading and actin polymerization in CD36-sufficient but not CD36-deficient mouse macrophages in vitro. The underlying mechanism was dependent on oxLDL-mediated CD36 signaling, which resulted in sustained activation of focal adhesion kinase (FAK) and inactivation of Src homology 2-containing phosphotyrosine phosphatase (SHP-2). The latter was due to NADPH oxidase-mediated ROS generation, resulting in oxidative inactivation of critical cysteine residues in the SHP-2-active site. Macrophage migration in the presence of oxLDL was restored by both antioxidants and NADPH oxidase inhibitors, which restored the dynamic activation of FAK. We conclude therefore that CD36 signaling in response to oxLDL alters cytoskeletal dynamics to enhance macrophage spreading, inhibiting migration. This may induce trapping of macrophages in the arterial intima and promote atherosclerosis.

Novel Role for p21-activated Kinase 2 in Thrombin-induced Monocyte Migration

“…Cell Migration-THP-1 and RAW 264.7 cell migration was measured using a modified Boyden chamber migration assay using Transwell inserts with 8-m porous membrane (Nalgene Nunc International, Rochester, NY) as described by Park et al (25). The outer surface of the membrane was coated with growth factor-reduced Matrigel (70%), and the inserts were placed in a 24-well tissue culture plate (coated surface of the membrane facing toward the outer chamber).…”

Effects of exogenous ganglioside GM1 on different stages of cell spreading studied by directly quantifying spreading rate

“…Therefore, the value of spread area becomes the criterion for judging the degree of cell spreading, making this method more objective. Most of the reported studies only investigated the spread areas at early time points ( 3 h) during cell spreading due to the assumption that most cells spread out within 1-3 h (Ezzell et al, 1997;Park et al, 2009). Our results from this method, however, imply that each stage of cell spreading can potentially be influenced by reagents (Figures 2B,.…”

FAK contributes to proteinuria in hypercholesterolaemic rats and modulates podocyte F‐actin re‐organization via activating p38 in response to ox‐LDL

“…In diabetic rats, boosted tyrosine phosphorylation of FAK was present in renal glomeruli, with unchanged total FAK expression and unregulated integrin β1 expression 11. Notably, CD36‐dependent sustained activation of FAK was revealed in ox‐LDL‐stimulated mouse macrophages in vitro , suggesting that FAK was a potential participant in lipid metabolism 12. Prior studies also demonstrated that FAK modulated cell motility by influencing the cytoskeleton, structures of cell adhesion sites and membrane protrusions 13.…”