Chronic liver injury results in activation of quiescent Hepatic Stellate Cells (qHSCs) into Collagen Type I-producing activated HSCs that make liver fibrotic. We identified ETS1/2 (E26 transformation-specific transcription factors 1/2) as lineage-specific transcription factors regulating HSC phenotypes. Here we investigated the role of ETS1/2 in HSCs in liver fibrosis using toxic liver injury models and 3D human liver spheroids. Liver fibrosis was induced in wild-type and HSC-specific Ets1 (Ets1ΔHSC) and Ets2 (Ets2ΔHSC) knockout mice by administration of carbon tetrachloride for 6 weeks, following cessation of liver injury for 2 weeks. Liver fibrosis was more severe in Ets1ΔHSC, and to lesser extent in Ets2ΔHSC, compared to wild-type mice. Regression of liver fibrosis was suppressed only in Ets1ΔHSC, indicating Ets1 as the predominant isoform maintaining quiescent-like phenotype in HSCs. Similar results were obtained in a MASH model using 3D human liver spheroids. Knockdown of ETS1 in human HSCs caused upregulation of fibrogenic genes in MASH human liver spheroids and prevented fibrosis regression. ETS1 regulated the qHSC phenotype via CRTC2/PGC1α/PPARγ pathway. Knockdown of CRTC2 (cAMP response element-binding protein (CREB)-regulated transcription co-activator 2) abrogated PPARγ responses and facilitated HSC activation. These findings suggest that ETS1 may represent a therapeutic target for anti-fibrotic therapy.
Wonseok Lee, Xiao Liu, Sara Brin Rosenthal, Charlene Miciano, Sadatsugu Sakane, Kanani Hokutan, Debanjan Dhar, Hyun Young Kim, David A. Brenner, Tatiana Kisseleva