1169-P: PNPLA3 148M Is More Susceptible to PA-Induced Endoplasmic Reticulum Stress-Associated Apoptosis in HepG2 Cells

Abstract

PNPLA3 is a major susceptibility gene for MAFLD and its polymorphic locus of rs738409 (I148M) is associated with MAFLD occurrence and progression. Endoplasmic reticulum (ER) stress and hepatocyte apoptosis induced by free fatty acids lipotoxicity in fatty liver cells play an important role in the progression of NAFLD [9]. PNPLA3 is a member of the non-calcium-dependent phospholipase A2 (iPLA2) family, iPLA2ε, and whether PNPLA3 148M has stronger phospholipase activity than 148I to promote apoptosis in hepatocyte is not clear. In this study, we constructed 148I/I knock-in HepG2 cell model by Cas9/sgRNA system on the basis of HepG2 carrying PNPLA3 148M/M. The PNPLA3 148MM and I/I cells were intervened with palmitic acid (PA) for 24 h, and cell lipid deposition was detected using oil red staining, apoptosis was observed by TUNEL, and western blot to detect PNPLA3 expression and ER stress-related CHOP apoptotic signaling pathway molecule expression. The results showed no difference in PNPLA3 expression and hepatocyte lipid deposition between PNPLA3 148M/M and 148I/I cells at baseline. However, after PA intervention, PNPLA3 148M/M cells exhibited more significant lipid deposition and apoptosis than 148I/I, as well as ER-related apoptotic molecules Bip, PERK, p-eIF2α, CHOP PUMA, BAX and cleaved caspase3 expression were more significantly increased. In conclusion, PNPLA3 148M/M cells were more significantly susceptible to PA-induced lipid deposition and endoplasmic reticulum stress-related apoptosis than 148I/I cells. Disclosure H. Liang: None. Funding Guangdong Natural Science Foundation (2020A1515010226)