Tài liệu Báo cáo khoa học: Nucleolin/C23 mediates the antiapoptotic effect of heat shock protein 70

Nucleolin/C23 mediates the antiapoptotic effect of heat

shock protein 70 during oxidative stress

Bimei Jiang1

, Bin Zhang1

, Pengfei Liang2

, Juan Song1

, Hongbing Deng1

, Zizhi Tu1

, Gonghua Deng1

and Xianzhong Xiao1

1 Department of Pathophysiology, Xiangya School of Medicine, Central South University, Changsha, Hunan, China

2 Department of Burns and Plastic Surgery, Xiangya Hospital, Central South University, Changsha, Hunan, China

Introduction

Characterized by cellular and nuclear shrinkage, cyto￾plasmic blebbing, chromatin condensation and DNA

fragmentation [1,2], apoptosis can cause irreversible

loss of terminally differentiated cardiac myocytes and,

therefore, contributes significantly to the pathogenesis

of many cardiovascular diseases. Apoptosis has been

identified in cardiac myocytes from patients suffering

from myocardial infarction, diabetic cardiomyopathy,

and end-stage congestive heart failure.

Apoptosis is a highly regulated programme of cell

death and can be mediated by death receptors in the

plasma membrane, as well as in the mitochondria and

the endoplasmic reticulum [3]. Studies on apoptotic

pathways in cardiomyocytes have revealed several

molecules as key regulators [4]. Heat shock protein

70 (Hsp70) is a major stress-inducible heat shock pro￾tein that has been shown to protect cells from

apoptosis induced by heat shock, tumour necrosis

factor, growth factor withdrawal, oxidative stress and

radiation [5,6]. Hsp70 is also a major self-preservation

protein in the heart; its overexpression enhances

myocardial tolerance to ischaemia ⁄reperfusion injury

in both transgenic animals [7] and cell cultures

[8]. Although substantial progress has been made in

understanding the control and mechanisms of apopto￾sis, how Hsp70 protects cardiomyocytes against apop￾tosis induced by a variety of stresses remains to be

investigated.

Keywords

apoptosis; cardiomyocytes; heat shock

protein 70; hydrogen peroxide;

nucleolin ⁄ C23

Correspondence

Xianzhong Xiao, Department of

Pathophysiology, Xiangya School of

Medicine, Central South University,

Changsha, Hunan 410008, China

Fax: +86 731 82355019

Tel: +86 731 2355019

E-mail: [email protected]

(Received 22 August 2009, revised 26

October 2009, accepted 23 November

2009)

doi:10.1111/j.1742-4658.2009.07510.x

Although heat shock protein 70 (Hsp70) has been shown to markedly inhi￾bit H2O2-induced apoptosis in C2C12 cells, and nucleolin ⁄ C23 has also

been implicated in apoptosis, the relationship of these two molecules is still

largely unknown. The aim of the current study was to investigate the

potential involvement of nucleolin ⁄ C23 in the antiapoptotic mechanism of

Hsp70. We found that primary cultures of neonatal rat cardiomyocytes

underwent apoptosis upon H2O2 treatment, and in these cells nucleo￾lin ⁄ C23 protein was highly unstable and had a half-life of less than 4 h.

However, transfection with Hsp70 greatly stabilized nucleolin ⁄ C23 and also

protected the cells from H2O2-induced apoptosis. When nucleolin ⁄ C23 was

knocked down with an antisense oligomer, H2O2-induced apoptosis became

more severe, even in Hsp70-overexpressed cells, demonstrating an essential

role of nucleolin ⁄ C23 in the antiapoptotic effects of Hsp70. Similar results

were obtained by both nuclear morphology observation and caspase-3

activity assay. Therefore, these data provide evidence that nucleolin ⁄ C23 is

an essential downstream effecter of Hsp70 in the protection of cardiomyo￾cytes against oxidative stress-induced apoptosis.

Abbreviations

DMEM, Dulbecco’s modified Eagle’s medium; FITC, fluorescein isothiocyanate; GAPDH, glyceraldehyde-3-phosphate dehydrogenase;

Hsp70, heat shock protein 70; PBS, phosphate-buffered saline; PI, pyridine iodination; SEM, standard error of the mean.

642 FEBS Journal 277 (2010) 642–652 ª 2009 The Authors Journal compilation ª 2009 FEBS