ITGBL1-MYH9 interaction in hepatic stellate cells acts as a mechano-regulator controlling liver fibrosis in mice

Résumé fourni par la source

Hepatic stellate cell (HSC) activation can lead to liver fibrosis, for which there are no effective treatments. Aberrant cytoskeletal reorganization is a central driver of HSC activation. Non-muscle myosin II (NM II) is known to regulate cytoskeleton remodeling via its actin cross-linking and contractile properties. However, the molecular players controlling actomyosin assembly and contractility in HSCs during liver fibrosis remain poorly defined. Here, we identified integrin β-like 1 (ITGBL1) as a gatekeeper of HSC quiescence by negatively regulating actomyosin contractility-driven mechanotransduction in HSCs. ITGBL1 expression was markedly elevated in activated HSCs found in patient and mouse fibrotic livers. Unexpectedly, HSC-specific Itgbl1 deficiency worsened liver fibrosis, whereas ITGBL1 overexpression in HSCs limited it, suggesting a protective role for ITGBL1 against a pathogenic HSC activation. Multi-omics and functional analyses revealed that ITGBL1 impaired F-actin filament organization in HSCs by disrupting myosin heavy chain 9 (MYH9, also named NM II heavy chain A)-dependent actomyosin assembly. In line, HSC-specific Myh9 deficiency or silencing of Myh9 in HSCs alleviated liver fibrosis. Taken together, our findings unveil the ITGBL1-MYH9 interaction acts as a critical mechano-regulatory brake that maintains cytoskeletal equilibrium and mechanical homeostasis in HSCs, providing a promising therapeutic strategy to combat liver fibrosis.

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