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Hepatology. 2018 Jun;67(6):2320-2337. doi: 10.1002/hep.29585. Epub 2018 Apr 19.

Dual catenin loss in murine liver causes tight junctional deregulation and progressive intrahepatic cholestasis.

Author information

1
Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, PA.
2
Department of General Surgery, School of Medicine, Xi'an Jiaotong University, China.
3
Pittsburgh Heart, Lung and Blood Vascular Medicine Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA.
4
Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA.
5
Pittsburgh Liver Research Center, University of Pittsburgh Medical Center and University of Pittsburgh School of Medicine, Pittsburgh, PA.
6
Department of Pharmacology, Toxicology and Therapeutics, Kansas University Medical Center, Kansas City, KS.
7
Children's Hospital of Pittsburgh, Pittsburgh, PA.
8
Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA.

Abstract

β-Catenin, the downstream effector of the Wnt signaling, plays important roles in hepatic development, regeneration, and tumorigenesis. However, its role at hepatocyte adherens junctions (AJ) is relatively poorly understood, chiefly due to spontaneous compensation by γ-catenin. We simultaneously ablated β- and γ-catenin expression in mouse liver by interbreeding β-catenin-γ-catenin double-floxed mice and Alb-Cre transgenic mice. Double knockout mice show failure to thrive, impaired hepatocyte differentiation, cholemia, ductular reaction, progressive cholestasis, inflammation, fibrosis, and tumorigenesis, which was associated with deregulation of tight junctions (TJ) and bile acid transporters, leading to early morbidity and mortality, a phenotype reminiscent of progressive familial intrahepatic cholestasis (PFIC). To address the mechanism, we specifically and temporally eliminated both catenins from hepatocytes using adeno-associated virus 8 carrying Cre-recombinase under the thyroid-binding globulin promoter (AAV8-TBG-Cre). This led to a time-dependent breach of the blood-biliary barrier associated with sequential disruption of AJ and TJ verified by ultrastructural imaging and intravital microscopy, which revealed unique paracellular leaks around individual hepatocytes, allowing mixing of blood and bile and leakage of blood from one sinusoid to another. Molecular analysis identified sequential losses of E-cadherin, occludin, claudin-3, and claudin-5 due to enhanced proteasomal degradation, and of claudin-2, a β-catenin transcriptional target, which was also validated in vitro.

CONCLUSION:

We report partially redundant function of catenins at AJ in regulating TJ and contributing to the blood-biliary barrier. Furthermore, concomitant hepatic loss of β- and γ-catenin disrupts structural and functional integrity of AJ and TJ via transcriptional and posttranslational mechanisms. Mice with dual catenin loss develop progressive intrahepatic cholestasis, providing a unique model to study diseases such as PFIC. (Hepatology 2018;67:2320-2337).

PMID:
29023813
PMCID:
PMC5893443
DOI:
10.1002/hep.29585
[Indexed for MEDLINE]
Free PMC Article

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