Abstract 20439: Sam68 Negatively Modulates Macrophage Autophagy in Atherosclerosis

Background: Macrophage autophagy regulates 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 macrophages, lentivirus-shRNA mediated knockdown of Sam68 (Sam68-KDn) led to a reduced protein level of total LC3, LC3-II, and p62/sqstm1 under basal culture condition, however, to a greater accumulation of LC3 in the presence of autolysosome inhibitor Bafliomycin A1, suggesting that Sam68 is physiologically a repressor of autophagy flux. Consistently, in HeLa/GFP-LC3 cells with Sam68-KDn, Bafliomycin A1 treatment also led to a greater autophagy flux than in control HeLa/GFP-LC3 cells, as revealed by autophagosome punctae counting (immuno-fluorescent microscopy) and median fluorescent intensity (flow cytometry). Notably, the mRNA levels of well-known transcriptional targets of autophagy related genes (MAP1L...