Cullin 3 (CUL3) is a central component of CUL3-RING ubiquitin (Ub) ligases (CRL3s), which mediate the ubiquitination and subsequent proteasomal degradation of numerous proteins involved in diverse cellular processes. CUL3 has been shown to regulate the proliferation of liver progenitor cells and the metabolic function of mature hepatocytes. However, its role in perinatal liver development and homeostasis remains largely unexplored. We first generated mice with an embryonic-onset hepatocyte-specific deletion of Cul3 (Cul3f/f; Alb-Cre+, Cul3LKO). Cul3LKO mice were born with lower body weights and showed a significant increase in liver-to-body weight ratio starting at postnatal day 5. They developed rapidly progressive liver failure, and none of them survived beyond four weeks of age. Liver from Cul3LKO mice showed a completely dysregulated architecture, extensive hepatocyte necrosis or dropout, massive lymphocyte infiltration, hepatic rosettes or pseudorosettes, and hemangioma. Most notably, they showed pathological features that partially resembled the human congenital disorder Caroli syndrome. These features included extensive ductal plate malformations, various liver cysts, congenital hepatic fibrosis (scarring of the liver), and hyperbilirubinemia. Molecular analyses revealed a reduction in hepatocyte differentiation markers (HNF4α and CEBPα), along with an increase in cholangiocyte markers (CK7 and CK19) and progenitor markers (AFP, PKM2, and beta-Catenin) in the Cul3LKO liver. Cul3LKO liver demonstrated significantly higher expression of hepatic necroptosis marker proteins, confirming extensive hepatocyte necrosis. All these pathological changes were more prominent in male Cul3LKO mice. Furthermore, CRISPR–Cas9-mediated CUL3 knockout in hepatoblastoma HepG2 cells and pharmacological inhibition of CUL3 neddylation with DI951 in primary hepatocytes recapitulated upregulation of cholangiocyte and progenitor marker expression. In conclusion, loss of CUL3 results in hepatocyte necrosis and cholangiocyte and progenitor cell proliferation, with specific histological and molecular features similar to those observed in human Caroli syndrome. Our study underscores the importance of CUL3 in preserving hepatocyte identity and viability and emphasizes its essential role in regulating hepatocyte and cholangiocyte lineage determination during perinatal liver development. Funding sources: This work was supported by the National Institute of Diabetes and Digestive and Kidney Diseases R01DK135657A1 and the National Heart, Lung and Blood Institute 2R01HL132182. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.
Nguyen et al. (Fri,) studied this question.