Background and objective: Persistent hepatic progenitor cells (HPC) activation resulting in ductular reaction (DR) is responsible for pathologic liver repair in cholangiopathies. Also, HPC/DR expansion correlates with fibrosis in several chronic liver diseases, including steatohepatitis. Increasing evidence indicates Notch signaling as a key regulator of HPC/DR response in biliary and more in general liver injuries. Therefore, we aimed to investigate the role of Notch during HPC/DR activation in a mouse model of steatohepatitis. Methods: Steatohepatitis was generated using methionine-choline deficient (MCD) diet. For hepatocyte lineage tracing, R26R-YFP mice were infected with AAV8-TBG-Cre. Results: MCD diet promoted a strong HPC/DR response that progressively diffused in the lobule, and correlated with increased fibrosis and TGF-β1 expression. Notch signaling was unchanged in laser-capture microdissected HPC/DR, whereas Notch receptors were down regulated in hepatocytes. However, in-vivo lineage tracing experiments identified discrete hepatocytes showing Notch-1 activation and expressing (the Notch-dependent) Sox9. Stimulation of AML-12 hepatocyte-cell line with immobilized Jag1 induced Sox9 and down-regulated albumin and BSEP expression. TGF-β1 treatment in primary hepatic stellate cells (HSC) induced Jag1 expression. In MCD diet-fed mice, αSMA-positive HSC were localized around Sox9 expressing hepatocytes, suggesting that Notch activation in hepatocytes was promoted by TGF-β1 stimulated HSC. In-vivo Notch inhibition reduced HPC response and fibrosis progression. Conclusion: Our data suggest that Notch signaling is an important regulator of DR and that in steatohepatitis, hepatocytes exposed to Jag1-positive HSC, contribute to pathologic DR by undergoing Notch-mediated differentiation towards an HPC-like phenotype. Given the roles of Notch in fibrosis and liver cancer, these data suggest mesenchymal expression of Jag1 as an alternative therapeutic target.

Morell, C., Fiorotto, R., Meroni, M., Raizner, A., Torsello, B., Cadamuro, M., et al. (2017). Notch signaling and progenitor/ductular reaction in steatohepatitis. PLOS ONE, 12(11) [10.1371/journal.pone.0187384].

Notch signaling and progenitor/ductular reaction in steatohepatitis

Morell, Carola M.
Primo
Membro del Collaboration Group
;
Torsello, Barbara
Membro del Collaboration Group
;
Cadamuro, Massimiliano
Membro del Collaboration Group
;
Spagnuolo, Gaia
Membro del Collaboration Group
;
Strazzabosco, Mario
Ultimo
Membro del Collaboration Group
2017

Abstract

Background and objective: Persistent hepatic progenitor cells (HPC) activation resulting in ductular reaction (DR) is responsible for pathologic liver repair in cholangiopathies. Also, HPC/DR expansion correlates with fibrosis in several chronic liver diseases, including steatohepatitis. Increasing evidence indicates Notch signaling as a key regulator of HPC/DR response in biliary and more in general liver injuries. Therefore, we aimed to investigate the role of Notch during HPC/DR activation in a mouse model of steatohepatitis. Methods: Steatohepatitis was generated using methionine-choline deficient (MCD) diet. For hepatocyte lineage tracing, R26R-YFP mice were infected with AAV8-TBG-Cre. Results: MCD diet promoted a strong HPC/DR response that progressively diffused in the lobule, and correlated with increased fibrosis and TGF-β1 expression. Notch signaling was unchanged in laser-capture microdissected HPC/DR, whereas Notch receptors were down regulated in hepatocytes. However, in-vivo lineage tracing experiments identified discrete hepatocytes showing Notch-1 activation and expressing (the Notch-dependent) Sox9. Stimulation of AML-12 hepatocyte-cell line with immobilized Jag1 induced Sox9 and down-regulated albumin and BSEP expression. TGF-β1 treatment in primary hepatic stellate cells (HSC) induced Jag1 expression. In MCD diet-fed mice, αSMA-positive HSC were localized around Sox9 expressing hepatocytes, suggesting that Notch activation in hepatocytes was promoted by TGF-β1 stimulated HSC. In-vivo Notch inhibition reduced HPC response and fibrosis progression. Conclusion: Our data suggest that Notch signaling is an important regulator of DR and that in steatohepatitis, hepatocytes exposed to Jag1-positive HSC, contribute to pathologic DR by undergoing Notch-mediated differentiation towards an HPC-like phenotype. Given the roles of Notch in fibrosis and liver cancer, these data suggest mesenchymal expression of Jag1 as an alternative therapeutic target.
Articolo in rivista - Articolo scientifico
Animals; Diet; Fatty Liver; Hepatocytes; Male; Mice; Mice, Inbred C57BL; Receptors, Notch; Stem Cells; Signal Transduction; Biochemistry, Genetics and Molecular Biology (all); Agricultural and Biological Sciences (all)
English
2017
12
11
e0187384
none
Morell, C., Fiorotto, R., Meroni, M., Raizner, A., Torsello, B., Cadamuro, M., et al. (2017). Notch signaling and progenitor/ductular reaction in steatohepatitis. PLOS ONE, 12(11) [10.1371/journal.pone.0187384].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/178719
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