Chromatin architecture as a checkpoint for NASH-associated liver injury

Nonalcoholic steatohepatitis (NASH) is a progressive liver disease that is characterized by liver injury, inflammation and fibrosis. NASH pathogenesis is linked to reprogramming of chromatin landscape in the liver that predisposes hepatocytes to stress-induced tissue injury. However, the molecular nature of the putative checkpoint that maintains chromatin architecture and preserves hepatocyte health remains elusive. Here we show that heterogeneous nuclear ribonucleoprotein U (hnRNPU), a nuclear matrix protein that governs chromatin architecture and gene transcription, is a critical factor that couples chromatin disruption to NASH pathogenesis. RNA-seq and ChIP-seq studies revealed an extensive overlap between hnRNPU occupancy and altered gene expression during NASH. Hepatocyte-specific inactivation of hnRNPU disrupted liver chromatin accessibility, activated the molecular signature of NASH and sensitized mice to diet-induced NASH pathogenesis. Mechanistically, hnRNPU deficiency stimulated the expression of a truncated isoform of TrkB that promotes inflammatory signaling in hepatocytes and stress-induced cell death. These findings illustrate a novel mechanism through which disruptions of chromatin architecture drive the emergence of disease-specific signaling patterns that promote liver injury and exacerbate NASH pathogenesis. 6 biological replicates were analyzied in each group for ATAC-seq (control vs liver specific knockout); 2 control and 3 liver specific knockout samples were used in RNA-seq