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Hepatology. 2017 Nov;66(5):1430-1443. doi: 10.1002/hep.29319. Epub 2017 Sep 29.

Critical role of CREBH-mediated induction of transforming growth factor β2 by hepatitis C virus infection in fibrogenic responses in hepatic stellate cells.

Author information

1
Department of Virology & Parasitology, Laboratory Animal Facilites & Services, Hamamatsu University School of Medicine, Hamamatsu, Japan.
2
2nd Department of Internal Medicine, Laboratory Animal Facilites & Services, Hamamatsu University School of Medicine, Hamamatsu, Japan.
3
Core Research Facilities of Basic Science (Molecular Genetics), Research Center for Medical Science, Tokyo, Japan.
4
Preeminent Medical Photonics Education & Resarch Center, Laboratory Animal Facilites & Services, Hamamatsu University School of Medicine, Hamamatsu, Japan.
5
Department of Internal Medicine (Endocrinology and Metabolism), Faculty of Medicine, University of Tsukuba, Tsukuba, Japan.
6
Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
7
Department of Laboratory Medicine, The Jikei University School of Medicine, Tokyo, Japan.

Abstract

Mechanisms of hepatic fibrogenesis induced by hepatitis C virus (HCV), one of the leading causes of liver fibrosis, are not fully understood. We studied transcriptional up-regulation of transforming growth factor β (TGF-β), especially TGF-β2, which is mediated by activation of liver-enriched transcription factor cAMP-responsive element-binding protein, hepatocyte specific (CREBH) triggered by HCV infection and its functional significance for induction of profibrogenic phenotypes by interaction of HCV-infected cells with hepatic stellate cells (HSCs). Compared to TGF-β1, expression of TGF-β2 mRNA was induced faster and to a higher level upon HCV infection. Serum TGF-β2 levels in hepatitis C patients were higher compared to those in healthy individuals and were positively correlated with hepatic fibrosis stages F0-F2. TGF-β2 promoter activity was decreased and increased, respectively, by silencing and overexpression of CREBH. CREBH recognition sites were identified in the TGF-β2 promoter. CREBH binding to the promoter and its increase in cells expressing HCV Core-NS2 were shown by gel mobility shift and chromatin immunoprecipitation, respectively. The active form of CREBH was detectable in HCV-infected chimeric mice with human livers and cells expressing HCV proteins. Involvement of CREBH in HCV-induced fibrogenic response was further demonstrated in the CREBH null-mutant mouse model. Fibrogenic phenotypes were assessed using co-cultures of HCV-infected cells and HSCs. Expressions of fibrogenic factors and TGF-β1 increasing in the co-cultures was prevented by TGF-β2- or CREBH silencing.

CONCLUSION:

CREBH was identified as a key positive regulator of TGF-β2 transcription in HCV-infected cells. TGF-β2 released from infected cells potentially contributes to cross-induction of TGF-β in an autocrine manner through its own signaling pathway, leading to an increase in fibrogenic responses in adjacent HSCs. (Hepatology 2017;66:1430-1443).

PMID:
28621467
DOI:
10.1002/hep.29319
[Indexed for MEDLINE]

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