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
ARTICLE HIGHLIGHTS
Research background

High mobility group box-1 (HMGB1) released by injured/dying cells becomes a key of damage-associated molecular patterns molecule to trigger inflammation responses leading to a series of tissue and organ damage, even diseases. But the details on how the injured hepatocytes released HMGB1 are to be elicited.

Research motivation

Hepatocytes are the most abundant cell type in the liver and the most easily attacked target, and loss of hepatocytes would contribute to various hepatic diseases. So, it is important to investigate the mechanism of HMGB1 release during hepatocyte injury or death.

Research objectives

To elicit HMGB1 release regulated by Sirt1 in injured/ dying hepatocytes, male C57BL/6J mice fed a high-fat diet (HFD) plus ethyl alcohol (etOH) were employed to assess the HMGB1 release and translocation from the nuclues to cytoplasm in injured hepatocytes. In vitro, mouse embryonic hepatocyte cell line BNL.CL2 incubated with H2O2 was further investigate the regulatory effect of Sirt1 on HMGB1 release. The main aim ofthis study was to understand HMGB1 release and its regulatory factors during hepatocyte injury/death, which would be a potential target for clinical therapy.

Research methods

Male C57BL/6J mice were fed an HFD plus etOH to establish a model of hepatocytes injury/death. Meanwhile, mouse embryonic hepatocyte cell line BNL.CL2 was cultured in vitro and treated with H2O2. Serum ALT, liver H2O2 content and catalase activity, lactate dehydrogenase and 8-hydroxy-2-deoxyguanosine content, NAD+ levels, Sirt1 activity were detected by spectrophotometry. HMGB1 release was measured by ELISA and its translocation was detected by immunohistochemistry/immunofluorescence or Western blot. The mRNA and protein levels were assayed by qPCR and Western blot, respectively. Acetylated HMGB1 and Parp1 were analyzed by immunoprecipitation.

Research results

After treatment with an HFD plus etOH in vivo or H2O2in vitro toinduce hepatocyte injury, HMGB1 was translocated from the nucleus to the cytoplasm and passively released outside. This process occured because HMGB1 was hyperacetylated owing to both Sirt1 protein and activity suppression. After treatment with Sirt1-siRNA or Sirt1 inhibitor EX527, hyperacetylated HMGB1 increased (P < 0.01). Further, Sirt1 activity was suppressed by H2O2, which could be reversed by the Parp1 inhibitor DIQ (P < 0.01).

Research conclusions

When hepatocytes injured/die, HMGB1 is translocated from the nucleus to the cytoplasm and finally released, which is related with hyperacetylated HMGB1 due to Sirt1 activity inhibition by NAD+ depletion caused by Parp1 overactivation.

Research perspectives

The future research will focus on herbs affecting this process to investigate the recovery of injured hepatocyte.