Tài liệu Báo cáo khoa học: Hepatic stimulator substance mitigates hepatic cell injury through

Hepatic stimulator substance mitigates hepatic cell injury

through suppression of the mitochondrial permeability

transition

Yuan Wu1,*, Jing Zhang1,*, Lingyue Dong1

, Wen Li1

, Jidong Jia2 and Wei An1

1 Department of Cell Biology and Municipal Key Laboratory for Liver Protection and Regulation of Regeneration, Capital Medical University,

Beijing, China

2 Liver Unit, Beijing Friendship Hospital, Capital Medical University, Beijing, China

Introduction

Hepatic stimulator substance (HSS) is expressed in the

liver cytosol of weanling or partially hepatectomized

adult rats, and was first described by LaBrecque and

Pesch [1]. A major function of this protein is to pro￾mote hepatocyte proliferation and liver regeneration

after partial hepatectomy [1–3]. The HSS-mediated

Keywords

apoptosis; hepatic stimulator substance;

mitochondria; mitochondrial membrane

potential; mitochondrial permeability

transition

Correspondence

W. An, Department of Cell Biology,

Municipal Key Laboratory for Liver

Protection and Regulation of Regeneration,

Capital Medical University, Beijing 100069,

China

Fax: +86 10 83911480

Tel: +86 10 83911480

E-mail: [email protected]

*These authors contributed equally to this

work

(Received 12 October 2009, revised 18

December 2009, accepted 23 December

2009)

doi:10.1111/j.1742-4658.2010.07560.x

Hepatic stimulator substance (HSS) has been shown to protect liver cells

from various toxins. However, the mechanism by which HSS protects

hepatocytes remains unclear. In this study, we established BEL-7402

cells that stably express HSS and analyzed the protective ability of HSS on

cells through mitochondrial permeability (MP). After administration of

carbonyl cyanide m-chlorophenylhydrazone (CCCP), a specific agent that

leads to depolarization of the mitochondrial transmembrane potential, the

apoptosis rate of HSS-expressing cells was significantly reduced, as

measured using Hoechst staining and flow cytometry. The mitochondrial

membrane transition and cytochrome c leakage were significantly inhibited

in the HSS-expressing cells as compared with the untransfected cells, and,

as a consequence, the cellular ATP content in the HSS-expressing cells was

relatively preserved. Additionally, decreased caspase-3 activity was

observed in the HSS-expressing cells treated with CCCP as compared with

the vector-transfected cells and cells expressing mutant HSS. Furthermore,

silencing of HSS expression using small interfering RNA accelerated

CCCP-induced apoptosis. In isolated mitochondria, recombinant HSS

reduced the release of cytochrome c induced by CCCP, indicating a possi￾ble role for HSS in regulation of mitochondrial permeability transition

(MPT). HSS-expressing BEL-7402 cells are resistant to CCCP injury, and

HSS protection is identical to that observed with cyclosporin A, an inhibi￾tor of MPT. Therefore, we propose that the protective effect of HSS may

be associated with blockade of MPT.

Abbreviations

ALR, augmenter of liver regeneration; CCCP, carbonyl cyanide m-chlorophenylhydrazone; COX IV, cytochrome c oxidase subunit IV;

CsA, cyclosporin A; HSS, hepatic stimulator substance; IM, inner membrane; JC-1, 5,5¢,6,6¢-tetrachloro-1,1¢,3,3¢-

tetraethylbenzimidazolocarbocyanine iodide; MP, mitochondrial permeability; MPT, mitochondrial permeability transition;

PTP, permeabilization transition pore; rHSS, recombinant hepatic stimulator substance; siRNA, small interfering RNA; wm, inner

transmembrane potential.

FEBS Journal 277 (2010) 1297–1309 ª 2010 The Authors Journal compilation ª 2010 FEBS 1297