Oxidized Low-Density Lipoprotein Promotes Macrophage Lipid Accumulation via the Toll-Like Receptor 4-Src Pathway

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Background:Uptake of oxidized low-density lipoprotein (oxLDL) by macrophages is recognized as a crucial step in the development of atherosclerosis, whereas the precise molecular mechanisms involving it remain to be elucidated.Methods and Results:This study focused on determining the role of toll-like receptor 4 (TLR4) and Src kinase in macrophage lipid accumulation. oxLDL significantly enhanced Src kinase activity and intracellular lipid contents in RAW264.7 macrophages, whereas the small interference RNA-mediated knockdown of TLR4 and Src or chemical inhibition of Src activity blocked oxLDL-induced lipid accumulation. Immunoprecipitation and immunofluorescence studies demonstrated that TLR4 was associated with Src on the plasma membrane upon oxLDL stimulation.Conclusions:The results of the present study suggest an essential role of TLR4-Src signaling in macrophages in the pathogenesis of atherosclerosis. (Circ J 2015; 79: 2509–2516)