In vivo CRISPR screening identifies BAZ2 chromatin remodelers as druggable regulators of mammalian liver regeneration

Abstract

Identifying new pathways that regulate mammalian regeneration is challenging due to the paucity of in vivo screening approaches. We employed pooled CRISPR knockout and activation screening in the regenerating liver to evaluate 165 chromatin regulatory proteins. Both screens identified the imitation-SWI chromatin remodeling components Baz2a and Baz2b, not previously implicated in regeneration. In vivo sgRNA, siRNA, and knockout strategies against either paralog confirmed increased regeneration. Distinct BAZ2-specific bromodomain inhibitors, GSK2801 and BAZ2-ICR, resulted in accelerated liver healing after diverse injuries. Inhibitor-treated mice also exhibited improved healing in an inflammatory bowel disease model, suggesting multi-tissue applicability. Transcriptomics on regenerating livers showed increases in ribosomal and cell cycle mRNAs. Surprisingly, CRISPRa screening to define mechanisms showed that overproducing Rpl10a or Rpl24 was sufficient to drive regeneration, whereas Rpl24 haploinsufficiency was rate limiting for BAZ2 inhibition-mediated regeneration. The discovery of regenerative roles for imitation-SWI components provides immediate strategies to enhance tissue repair.

Keywords: CRISPRa; bromodomain inhibitors; chromatin remodeling; colitis; hepatocyte proliferation; inflammatory bowel disease; in vivo CRISPR screening; liver regeneration; partial hepatectomy; protein synthesis.