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

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).

• Authors: Takeshi Chida, Masahiko Ito, Kenji Nakashima, Yumi Kanegae, Takuya Aoshima, Shuji Takabayashi, Kazuhito Kawata, Yoshimi Nakagawa, Masahiro Yamamoto, Hitoshi Shimano, Tomokazu Matsuura, Yoshimasa Kobayashi, Takafumi Suda, Tetsuro Suzuki
• Journal: Hepatology (Baltimore, Md.) (Hepatology) Vol. 66 Issue 5 Pg. 1430-1443 (11 2017) ISSN: 1527-3350 [Electronic] United States
• PMID: 28621467 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2017 by the American Association for the Study of Liver Diseases.

Chemical References

• Creb3l3 protein, mouse
• Cyclic AMP Response Element-Binding Protein
• Transforming Growth Factor beta1
• Transforming Growth Factor beta2

Topics

• Animals
• Autocrine Communication
• Cyclic AMP Response Element-Binding Protein (metabolism)
• Fibrosis
• Gene Expression Regulation
• Hepatic Stellate Cells (pathology)
• Hepatitis C (complications, metabolism, pathology)
• Liver (pathology)
• Liver Cirrhosis (metabolism, virology)
• Male
• Mice, Inbred C57BL
• Paracrine Communication
• Transforming Growth Factor beta1 (metabolism)
• Transforming Growth Factor beta2 (metabolism)