β1 integrin signaling governs necroptosis via the chromatin remodeling factor CHD4
Fibrosis, characterized by sustained activation of myofibroblasts and excessive extracellular matrix (ECM) deposition, is known to be associated with chronic inflammation. RIPK3, the central kinase of necroptosis signaling, is upregulated in fibrosis and contributes to the TNF-mediated inflammation. In bile duct ligation-induced liver fibrosis, we found that myofibroblasts are the major cell type expressing RIPK3. Genetic ablation of {beta}1 integrins, the major profibrotic ECM receptors in fibroblasts, not only abolished ECM fibrillogenesis but also blunted RIPK3 expression via an epigenetic mechanism mediated by the chromatin remodeling factor CHD4. While the function of CHD4 has been conventionally linked to NuRD and ChAHP complexes, we found that CHD4 potently repressed a set of genes, including Ripk3, with high locus specificity but independent of either the NuRD or ChAHP complex. Thus, our data uncover that {beta}1 integrin intrinsically links fibrotic signaling to RIPK3-driven inflammation via a novel mode of action of CHD4.