Planas Paz, Lara, Pikiolek, Monika, Cochran, Nadire, Orsini, Vanessa, Bergling, Sebastian, Neri, Marilisa, Schuierer, Sven, Yang, Zinger, Cobos, Carlos Manuel, Muhic, Jasna, Hoppe, Philipp, Alford, John, Russ, Carsten, Reece-Hoyes, John, Calabrese, Diego, Cuttat-Theurillat, Rachel, Waldt, Annick, Nigsch, Florian, Gubser Keller, Caroline, Nicholson, Thomas, Mao, Xiaohong, Yang, Yi, Heim, Markus, Terracciano, Luigi, Bouwmeester, Antonius, Cong, Feng, Mcallister, Gregory, Hoffman, Gregory, Roma, Guglielmo and Tchorz, Jan (2019) YAP, but Not RSPO-LGR4/5, Signaling in Biliary Epithelial Cells Promotes a Ductular Reaction in Response to Liver Injury. Nature cell biology, x (x). x-x. ISSN na

Abstract

The liver has an intrinsically high capacity to regenerate involving several distinct cellular niches. Hepatic progenitor cells (HPCs) transiently appear around the portal vein following damage to support liver regeneration. Despite the clinical relevance of HPC-mediated liver regeneration, the regulatory mechanisms controlling HPC response are poorly understood. Liver organoids can be clonally expanded in vitro and differentiated into both hepatocytes and biliary cells, thereby displaying characteristics of bipotential HPCs. Here, we performed a CRISPR loss-of-function (LOF) screen in liver organoids, highlighting pathways regulating HPC expansion in vitro, followed by in vivo validation using drug-induced HPC response in transgenic mice. We show that the YAP/Hippo pathway is essential for HPC growth in vitro and liver-specific YAP1 LOF impairs HPC response in vivo. While Rspo-mediated Wnt/β-Catenin signalling is required for liver organoid formation and growth in vitro, blocking RSPO-induced Wnt/β-Catenin activation by Lgr4/5 LOF in vivo does not affect HPC response. Detailed spatiotemporal analysis of Wnt/β-Catenin reporter mice and single cell RNA sequencing (scRNA-Seq) of EpCam+ cells isolated during HPC response indicate absence of Wnt/β-Catenin signalling and no expression of the Rspo-Lgr4/5-Znrf3/Rnf43 module components, whereas YAP signalling is prominent in EpCam+ cells. However, periportal hepatocytes show Axin2, Lgr4 and Lgr5 expression during HPC response and Lgr4/5 LOF impairs resolution of HPC response during recovery, suggesting that Wnt/β-Catenin signalling in periportal hepatocytes is important for HPC response resolution and portal tract repair. Our data highlight time-sensitive requirement of growth signalling pathways in initiating and controlling key regulatory pathways of HPC response and liver regeneration.

Item Type:	Article
Date Deposited:	14 Aug 2025 00:45
Last Modified:	14 Aug 2025 00:45
URI:	https://oak.novartis.com/id/eprint/38674