Abstract 19442: Molecular Crosstalk Between Necroptosis and Autophagy Signaling Pathways: Roles of p62 and p53

Purpose: Necroptosis, a programmed cell death, has been implicated in various pathological conditions including heart failure. Here we examined whether and how receptor-interacting protein kinase (RIP) 1-dependent necroptotic signal modulates autophagy in cardiomyocytes, focusing on two modulators of autophagy, p62 and p53. Methods and Results: In H9c2 cells, the necroptotic pathway was activated by co-incubation with TNF (50 ng/ml) and z-VAD-fmk (zVAD, 20 μM), a pan-caspase inhibitor. TNF/zVAD increased LDH in the culture medium, which was prevented by necrostatin-1, a RIP1 inhibitor, and attenuated by rapamycin, a promoter of autophagy. The protective effect of rapamycin was blocked by Atg5 knockdown, confirming role of autophagy in the protection. TNF/zVAD did not affect phosphorylation of protein kinases that inhibit autophagy (Akt and p70S6K, a kinase downstream of mTORC1) and/or activate autophagy (AMPK, ULK1 and VASP, a target downstream of PKA). However, TNF/zVAD suppressed autophagic flux that wa...