SPAG5 deficiency activates autophagy to reduce atherosclerotic plaque formation in ApoE-/- mice

Autophagy, as a regulator of cell survival, plays an important role in atherosclerosis (AS). Sperm associated antigen 5 (SPAG5) is closely associated with the classical autophagy pathway, PI3K/Akt/mTOR signaling pathway. This work attempted to investigate whether SPAG5 can affect AS development by regulating autophagy.

This work demonstrated that SPAG5 knockdown alleviated AS development through activating autophagy. Thus, SPAG5 may be a potential target for AS therapy.

Human umbilical vein endothelial cells (HUVECs) were treated with oxidized-low density lipoprotein (ox-LDL) to induce cell damage. ApoE-/- mice were fed a Western diet to establish an AS mouse model. Haematoxylin and eosin (H&E) staining and Oil Red O staining evaluated the pathological changes and in lipid deposition in aortic tissues. CCK-8 and flow cytometry detected cell proliferation and apoptosis. Immunohistochemistry, Enzyme linked immunosorbent assay, qRT-PCR and western blotting assessed the levels of mRNA and proteins.

Ox-LDL treatment elevated SPAG5 expression and the expression of autophagy-related proteins, LC3-I, LC3-II, Beclin-1, and p62, in HUVECs. GFP-LC3 dots were increased in ox-LDL-treated HUVECs and LPS-treated HUVECs. SPAG5 knockdown reversed both ox-LDL and LPS treatment-mediated inhibition of cell proliferation and promotion of apoptosis in HUVECs. SPAG5 silencing further elevated autophagy and repressed the expression of PI3K, p-Akt/Akt, and p-mTOR/mTOR in ox-LDL-treated HUVECs. 3-MA (autophagy inhibitor) treatment reversed SPAG5 silencing-mediated increase of cell proliferation and decrease of apoptosis in ox-LDL-treated HUVECs. In vivo, SPAG5 knockdown reduced atherosclerotic plaques in AS mice through activating autophagy and inhibiting PI3K/Akt/mTOR signaling pathway.