Okina, Y;
Sato-Matsubara, M;
Matsubara, T;
Daikoku, A;
Longato, L;
Rombouts, K;
Thanh Thuy, LT;
... Kawada, N; + view all
(2020)
TGF-β-driven reduction of cytoglobin leads to oxidative DNA damage in stellate cells during non-alcoholic steatohepatitis.
Journal of Hepatology
10.1016/j.jhep.2020.03.051.
(In press).
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Pinzani_TGF-β-driven reduction of cytoglobin leads to oxidative DNA damage in stellate cells during non-alcoholic steatohepatitis_Pre-proof.pdf - Accepted Version Download (11MB) | Preview |
Abstract
BACKGROUND: Cytoglobin (CYGB) is a respiratory protein that acts as a scavenger of reactive oxygen species. Although CYGB is expressed uniquely in hepatic stellate cells (HSCs) in the liver, the molecular role of CYGB in human HSC activation and human liver disease remains uncharacterised. The aim of this study was to reveal the mechanism by which TGF-β1/SMAD2 pathway regulates human CYGB promoter and the pathophysiological function of CYGB in human non-alcoholic steatohepatitis (NASH). METHODS: Immunohistochemical staining was performed using human NASH biopsy specimens. Molecular and biochemical analysis were performed by western blotting, quantitative PCR, and luciferase and immunoprecipitation assays. Hydroxyl radicals (•OH) and oxidative DNA damage were measured using an •OH-detectable probe and 8-hydroxy-2’-deoxyguanosine (8-OHdG) ELISA. RESULTS: In culture, TGF-β1-pretreated human hepatic stellate cells (HHSteCs) exhibited lowered CYGB levels together with increased NADPH oxidase 4 (NOX4) expression and were primed for H_{2}O_{2}-triggered OH production and 8-OHdG generation. Overexpression of human CYGB in HHSteCs cancelled out those effects of TGF-β1. Electron spin resonance demonstrated direct •OH-scavenging activity of recombinant human CYGB. Mechanistically, pSMAD2 reduced CYGB transcription by recruiting the M1 repressor isoform of SP3 to the human CYGB promoter at nucleotide positions +2–{+}^13 from the transcription start site. The same repression did not occur on the mouse Cygb promoter. TGF-β1/SMAD3 mediated αSMA and collagen expression. Consistent with those observations in cultured HHSteCs, CYGB expression was negligible, but 8-OHdG was abundant, in activated αSMA^{+}pSMAD2^{+}- and αSMA^{+}NOX4^{+}-positive hepatic stellate cells from human NASH patients with advanced fibrosis. CONCLUSIONS: Downregulation of CYGB by the TGF-β1/pSMAD2/SP3-M1 pathway brings about •OH-dependent oxidative DNA damage in activated hepatic stellate cells from human patients with NASH.
| Type: | Article |
|---|---|
| Title: | TGF-β-driven reduction of cytoglobin leads to oxidative DNA damage in stellate cells during non-alcoholic steatohepatitis |
| Location: | Netherlands |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1016/j.jhep.2020.03.051 |
| Publisher version: | https://doi.org/10.1016/j.jhep.2020.03.051 |
| Language: | English |
| Additional information: | © 2020 European Association for the Study of the Liver. Published by Elsevier B.V. under a Creative Commons license (https://creativecommons.org/licenses/by-nc-nd/4.0/). |
| Keywords: | NAFLD/NASH, TGF-β1, cytoglobin, hepatic stellate cells, liver fibrosis, oxidative stress |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Medicine UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Medicine > Inst for Liver and Digestive Hlth |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10096800 |
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