RNA-binding protein LARP6 coordinates hepatic stellate cell activation and liver fibrosis.

Metabolic syndrome and excessive alcohol consumption (MetALD) result in liver injury and fibrosis, which are driven by increased collagen production by activated hepatic stellate cells (HSCs). Our previous studies demonstrated that LARP6, an RNA-binding protein, may facilitate collagen production. However, the expression and function of LARP6 as a regulator of fibrosis development in a disease-relevant model remain poorly understood. We demonstrated that LARP6 was upregulated in human activated HSCs in metabolic dysfunction-associated steatohepatitis (MASH) and MetALD. By using single-nucleus RNA-seq and assay for transposase-accessible chromatin sequencing, we showed that JUNB upregulated LARP6 expression in activated HSCs. Moreover, LARP6 knockdown in human HSCs suppressed fibrogenic gene expression. By integrating enhanced crosslinking and IP analysis and ribosome profiling in HSCs, we showed that LARP6 interacted with mature mRNAs comprising more than 300 genes, including RNA structural elements within COL1A1, COL1A2, and COL3A1 to regulate mRNA expression and translation. IP-mass spectrometry analysis demonstrated LARP6 protein-protein interactions with mRNA translation components and the actin cytoskeleton. Furthermore, Dicer substrate siRNA-based HSC-specific gene knockdown or pharmacological inhibition of LARP6 attenuated fibrosis development in human MASH and MetALD liver spheroids. Our results suggest LARP6 plays a key role in fibrogenic gene regulation and that targeting LARP6 in human HSCs may represent a therapeutic approach for liver fibrosis.