Basic Study
Copyright ©The Author(s) 2019. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Sep 28, 2019; 25(36): 5434-5450
Published online Sep 28, 2019. doi: 10.3748/wjg.v25.i36.5434
High mobility group box-1 release from H2O2-injured hepatocytes due to sirt1 functional inhibition
Ting-Jie Ye, Yan-Lin Lu, Xiao-Feng Yan, Xu-Dong Hu, Xiao-Ling Wang
Ting-Jie Ye, Yan-Lin Lu, Xiao-Feng Yan, Xu-Dong Hu, Xiao-Ling Wang, Department of Biology, School of Basic Medical Sciences, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
Yan-Lin Lu, Department of Oncology and Institute of Traditional Chinese Medicine in Oncology, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200032, China
Author contributions: Ye TJ, Lu YL, and Yan XF performed the experiments, collected the data, and prepared the figures and tables; Wang XL and Ye TJ obtained the funding and designed the experiments; Wang XL and Hu XD supervised the project and wrote and finalized the manuscript.
Supported by the National Natural Science Foundation of China, No. 81503367 and No. 81703832.
Institutional review board statement: All procedures involving animals were approved by the Animal Ethics Committee of Shanghai University of Traditional Chinese Medicine.
Institutional animal care and use committee statement: All procedures involving animals were approved by the Animal Ethics Committee of Shanghai University of Traditional Chinese Medicine. (protocol number: PZSHUTCM190419001).
Conflict-of-interest statement: The authors declared that they have no conflict of interest.
ARRIVE guidelines statement: The authors have read the ARRIVE guidelines, and the manuscript was prepared and revised according to the ARRIVE guidelines.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Xiao-Ling Wang, MD, Full Professor, Department of Biology, School of Basic Medical Sciences, Shanghai University of Traditional Chinese Medicine, 1200 Cailun Road, Pudong, Shanghai 201203, China. shengwuwang12@126.com
Telephone: +86-21-51322585
Received: April 26, 2019
Peer-review started: April 26, 2019
First decision: May 24, 2019
Revised: August 7, 2019
Accepted: August 19, 2019
Article in press: August 19, 2019
Published online: September 28, 2019
Processing time: 155 Days and 23.4 Hours
Abstract
BACKGROUND

High mobility group box-1 (HMGB1), recognized as a representative of damage-associated molecular patterns, is released during cell injury/death, triggering the inflammatory response and ultimately resulting in tissue damage. Dozens of studies have shown that HMGB1 is involved in certain diseases, but the details on how injured hepatocytes release HMGB1 need to be elicited.

AIM

To reveal HMGB1 release mechanism in hepatocytes undergoing oxidative stress.

METHODS

C57BL6/J male mice were fed a high-fat diet for 12 wk plus a single binge of ethanol to induce severe steatohepatitis. Hepatocytes treated with H2O2 were used to establish an in vitro model. Serum alanine aminotransferase, liver H2O2 content and catalase activity, lactate dehydrogenase and 8-hydroxy-2-deoxyguanosine content, nicotinamide adenine dinucleotide (NAD+) levels, and Sirtuin 1 (Sirt1) activity were detected by spectrophotometry. HMGB1 release was measured by enzyme linked immunosorbent assay. HMGB1 translocation was observed by immunohistochemistry/immunofluorescence or Western blot. Relative mRNA levels were assayed by qPCR and protein expression was detected by Western blot. Acetylated HMGB1 and poly(ADP-ribose)polymerase 1 (Parp1) were analyzed by Immunoprecipitation.

RESULTS

When hepatocytes were damaged, HMGB1 translocated from the nucleus to the cytoplasm because of its hyperacetylation and was passively released outside both in vivo and in vitro. After treatment with Sirt1-siRNA or Sirt1 inhibitor (EX527), the hyperacetylated HMGB1 in hepatocytes increased, and Sirt1 activity inhibited by H2O2 could be reversed by Parp1 inhibitor (DIQ). Parp1 and Sirt1 are two NAD+-dependent enzymes which play major roles in the decision of a cell to live or die in the context of stress . We showed that NAD+ depletion attributed to Parp1 activation after DNA damage was caused by oxidative stress in hepatocytes and resulted in Sirt1 activity inhibition. On the contrary, Sirt1 suppressed Parp1 by negatively regulating its gene expression and deacetylation.

CONCLUSION

The functional inhibition between Parp1 and Sirt1 leads to HMGB1 hyperacetylation, which leads to its translocation from the nucleus to the cytoplasm and finally outside the cell.

Keywords: Sirtuin1; Poly ADP-ribose polymerase 1; High mobility group box-1; Hepatocytes; Hydrogen peroxide

Core tip: High mobility group box 1 (HMGB1) is a nuclear protein that non-specifically binds to the minor grooves in DNA. Once released passively by necrotic and damaged cells, HMGB1 will become a damage-associated molecular pattern molecule triggering the inflammatory response and ultimately results in tissue damage. In the present study, we found that HMGB1 is released from H2O2-injured hepatocytes due to Sirt1 functional inhibition.