A new study published in Nature Communications proposes that alcohol-related liver disease RNA splicing errors trap damaged liver cells in a non-functional middle state, preventing regeneration even after a patient stops drinking, and identifies an inflammatory pathway that, when blocked in laboratory conditions, partially reversed the problem.
What the researchers claim, and on what basis
The study comes from a collaboration involving researchers at the University of Illinois Urbana-Champaign, Duke University, and the Chan Zuckerberg Biohub Chicago. The team compared healthy liver tissue with samples from people with alcohol-associated hepatitis or cirrhosis, the latter obtained from Johns Hopkins University Hospital through an initiative supported by the National Institute on Alcohol Abuse and Alcoholism.
The central finding is that diseased liver cells had begun moving away from their mature state toward a regenerative, progenitor-like state, but could not complete the transition. The researchers describe these cells as neither functional adult cells nor dividing progenitor cells. In their account, this cellular limbo compounds itself: as more cells become stuck, greater pressure falls on the remaining functional cells, which then attempt to regenerate and risk becoming trapped in the same way.
Alcohol-associated liver disease is, by the study’s account, the leading cause of liver-related mortality worldwide, linked to roughly 3 million deaths each year. ‘The only real life-saving treatment option once a patient reaches the liver failure stage in those diseases is transplantation,’ said U. of I. biochemistry professor Auinash Kalsotra, who co-led the study with Duke University School of Medicine professor Anna Mae Diehl. ‘But if we understood why these livers were failing, maybe we could intervene.’
Alcohol-related liver disease RNA splicing and the ESRP2 protein
Rather than simply measuring total RNA and protein levels, the team used deep RNA sequencing and computational analysis to examine how RNA fragments were being edited inside liver cells. RNA splicing is the process by which cells cut and rejoin segments of RNA molecules before using them as instructions to build proteins. Different splice combinations can produce proteins with different functions or, critically, different destinations inside the cell.
The researchers found widespread mis-splicing across thousands of genes in diseased liver samples. They traced a significant part of this to low levels of a protein called ESRP2, which normally helps ensure RNA is spliced correctly. With ESRP2 deficient, many proteins were still being produced in roughly normal amounts, but were ending up in the wrong compartment of the cell, stuck in the cytoplasm rather than reaching the nucleus, where they are needed to regulate regeneration.
The paper identifies splicing defects in two specific ESRP2 targets, Tcf4 and Slk, as particularly consequential. According to the Nature Communications paper, mis-splicing of these genes alters their nuclear localisation and activities, disrupting WNT and Hippo signalling pathways, both of which are involved in cell growth and tissue repair. That level of mechanistic specificity is useful, because it gives researchers concrete molecular targets rather than a vague claim that ‘splicing goes wrong’.
Mice lacking the gene that produces ESRP2 developed patterns of liver injury and failed regeneration resembling those seen in people with advanced alcohol-associated hepatitis, which the researchers argue strengthens the causal link.
Can the damage be reversed?
The researchers traced the suppression of ESRP2 back to inflammation. When the liver processes alcohol, the resulting tissue damage draws in immune and support cells that release inflammatory and growth factors. The study found these signals suppress both the production and activity of ESRP2.
The team then tested whether blocking one of those signals could reverse the effect. In laboratory cultures of liver cells exposed to TGF-β, a key inflammatory factor, the researchers treated cells with a TGF-β receptor type I/II inhibitor called LY2109761. According to the Nature Communications paper, treatment with LY2109761 reinstated ESRP2 expression and restored the splicing of its target transcripts. The experiment was conducted in cell cultures, not in patients, and that distinction matters: laboratory results of this kind frequently fail to translate into clinical benefit.
Kalsotra described the findings as a potential ‘launching pad for future clinical studies’, suggesting that mis-spliced RNA molecules could serve as diagnostic markers, and that correcting splicing defects might improve recovery in alcohol-associated liver disease. The research was supported by the National Institutes of Health, the Chan-Zuckerberg Biohub Chicago, the Duke Endowment, and the Muscular Dystrophy Association. Whether any of this translates to a treatment will depend on results that do not yet exist, but the molecular pathway is now, at least, named and partially characterised.
