Abstract 376: Sam68 Suppresses Autophagy in Macrophages and Promotes Atherosclerosis

Background: Recent experimental evidence suggests that autophagy inhibits the pathogenesis of atherosclerosis. The Src-associated substrate during mitosis of 68 kDa (Sam68) belongs to the family of KH domain RNA binding protein; its role in macrophage autophagy and atherosclerosis has not been studied. Methods & Results: In Raw264.7 macrophage cell line, lentivirus-shRNA mediated knockdown of Sam68 (Sam68-KDn) led to a reduced level of LC3-I, LC3-II, and p62/sqstm1 proteins at basal culture condition, however, to a faster accumulation of these proteins with Bafliomycin A1 (autolysosome inhibitor) treatment, indicating an accelerated autophagy flux. Consistently, Sam68-KDn HeLa/GFP-LC3 cells displayed more autophagosome punctae counts (by immuno-fluorescent microscopy) and greater LC3-II specific median fluorescent intensity (by flow cytometry) than control HeLa/GFP-LC3 cells when treated with Bafliomycin A1. Notably, quantitative RT-PCR analyses revealed that Sam68-KDn did not alter mRNA expression of kno...