Poster abstracts
Poster number 39 submitted by Diptatanu Das
Dysregulated RNA splicing network drives regeneration failure causing hepatic decompensation in alcohol-associated liver disease
Diptatanu Das (Department of Biochemistry, University of Illinois, Urbana-Champaign), Anuprova D. Bhowmik (Department of Biochemistry, University of Illinois, Urbana-Champaign), Arnab K. Roy (Department of Biochemistry, University of Illinois, Urbana-Champaign), Rajesh Dutta (Division of Gastroenterology, Department of Medicine, Duke University Health System), Anna M. Diehl (Division of Gastroenterology, Department of Medicine, Duke University Health System), Auinash Kalsotra (Department of Biochemistry, University of Illinois, Urbana-Champaign)
Abstract:
Alcohol-associated liver diseases (ALDs) are the primary cause of liver-related mortality worldwide, accounting for ~50% of all liver transplants. ALD progresses from alcohol-associated fatty liver (AFL) to steatohepatitis (SAH)—characterized by inflammation and acute-on chronic hepatocellular injury. While a normal liver is renowned for its ability to regenerate, why it fails in ALD remains unclear. Here, we performed comprehensive multi-omic profiling of healthy and diseased human livers using bulk and single-nucleus RNA- plus ATAC-seq. We report that hepatic immune milieu alterations in ALD prevent hepatocytes from transitioning to a proliferative progenitor-like state, trapping them into an unproductive intermediate state. We found reduced expression of adult transcription factors (TFs), in agreement with their chromatin states, but the expression of fetal TFs, in contrast to their chromatin accessibility, did not increase in ALD. This discordance between gene expression and chromatin accessibility motivated us to reason that post-transcriptional mechanisms might be dominant in driving altered activity of key genes responsible for cellular transitions. We found striking changes in RNA binding protein (RBP) expression, particularly ESRP, PTBP, and SR families, that cause misregulation of developmentally controlled RNA splicing in ALD. Our data pinpoint ESRP2 as a pivotal disease-sensitive RBP and support a causal role for its deficiency in ALD pathogenesis. We discovered that ESRP2 downregulation decreased inclusion of nuclear localization signal (NLS)-encoding exons of two cellular state-associated proteins – SLK and Wnt effector TCF4. We found cytoplasmic enrichment of SLK and TCF4 in human SAH livers. Using antisense oligonucleotides (ASOs), we recapitulated the disease-linked missplicing of Slk and Tcf4 in hepatocyte cultures, and studied how defects in SLK and TCF4 nuclear localization disrupts WNT and Hippo signaling pathways, which are critical for normal liver regeneration. In summary, our results demonstrate that dysregulated RNA splicing impedes regeneration in ALD, eventually leading to hepatic decompensation and liver failure.
Keywords: Alternative Splicing, Alcohol-associated Liver Disease, nuclear localization