12220 Impaired Esrra-mediated Regulation Of Lysosomal Protein Translation And Autophagy In MASH: Restoration And MASH Reversal By Alternate Day Fasting

Abstract Disclosure: M. Tripathi: None. K. Gauthier: None. R. Sandireddy: None. S. Park: None. V. Giguere: None. P.K. Chow: None. S. Ghosh: None. D.P. McDonnell: None. P.M. Yen: None. B. Singh: None. The regulation of global and specific protein synthesis during the progression of metabolic dysfunction-associated steatohepatitis (MASH) is poorly understood. Accordingly, we performed a comprehensive analyses of protein translation by employing label-free quantitative proteomics, puromycin-labeling, and polysome profiling, and found a reduction in protein synthesis during lipotoxic stress in vitro and in liver tissues from MASH mouse models. We also found that expression of estrogen receptor-related receptor-α(ERRa/Esrra) and ribosomal Rplp1 were significantly downregulated at protein levels. Additionally, Esrra recruitment was decreased on the Rplp1 promoter, and led to diminished Rplp1 mRNA and protein expression. Taken together, these events reduced overall translation activity and the specific translation of lysosomal (e.g.,Lamp2, Ctsd) and autophagy (e.g., Sqstm1, Map1lc3b) proteins during MASH. Moreover, Esrra-Rplp1-mediated translation of these lysosomal and autophagy proteins and autophagy was compromised in MASH patients and liver-specific Esrra-deficient mice. Remarkably, alternate day fasting induced hepatic Esrra expression and reactivated Esrra-Rplp1 signaling in mice with MASH, leading to the re-expression of autophagy and lysosomal proteins to restore autophagy and reduce lipotoxicity, inflammation, and fibrosis. Thus, the Esrra-Rplp1-mediated translation of lysosomal and autophagy proteins critical for preventing lipotoxicity, inflammation, and fibrosis was suppressed during MASH. Reactivation of this pathway by intermittent fasting was able to reverse MASH. Our findings showed that Esrra not only regulated the transcription of genes involved in lipid metabolism, but also the specific translation of autophagy and lysosomal proteins via induction of Rplp1; thus, providing a molecular explanation for the beneficial hepatic effects of alternate day fasting in MASH. Presentation: 6/2/2024