AAS ›› 2015, Vol. ›› Issue (3): 329-335.doi: 10.16098/j.issn.0529-1356.2015.03.007

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Insulin-like growth factor-1 protecting cardiomyocytes from apoptosis by down-regulating transcription factor basic transcription element binding protein through extracellular regulated kinase 1/2 pathway

ZHANG Jian-kai1 CUI Xiao-jun1 XU Xiao-ling2 DING Bi-lan2 LI Jin-ju2 LI Tao3 WU Zhu-guo 4*   

  1. 1.Department of Human Anatomy, Basic Medical College; 2.Postgraduate Academy; 3.Guangdong Provincial Key Laboratory of Medical Molecular Diagnosis;4.The Second Clinical College, Guangdong Medical College, Guangdong Dongguan 523808, China
  • Received:2014-11-24 Revised:2015-01-29 Online:2015-06-06 Published:2015-06-06
  • Contact: WU Zhu-guo E-mail:zhangjiankai2002@163.com

Abstract:

Objective To investigate gene regulation mechanism of insulin-like growth factor-1 (IGF-1) anti-apoptotic effect on rat cardiomyocytes. Methods Primary neonatal rat cardiomyocytes (NRCMs) were cultured in vitro,IGF-1(10nmol/L) was added with different signal transduction pathway inhibitors [phosphatidylinositol 3-kinase(PI3K), extracellular regulated kinase (ERK)1/2 and Raf-1] respectively (20μmol/L). The gene expression of basic transcription element binding protein (BTEB) was detected by RT-PCR and Western blotting, by which the pathway of IGF-1 down-regulated BTEB gene expression was judged. NRCMs were treated with 100umol/L hydrogen peroxide (H2O2) to induce apoptosis. BTEB specific siRNA was transfected into the cells by Lipofectamine 2000.Myocardial cells apoptosis was detected by DNA-ladder analysis, Annexin V-FITC/PI dual staining,Caspase-3 activity assay and Hoechst33258 staining. Results The mRNA and protein expression levels of BTEB gene in NRCMs were down-regulated significantly after IGF-1 had stimulated for 60 minutes. Compared with control groups, BTEB mRNA and protein expression in ERK1/2 pathway inhibitor PD98059 group was significantly higher (P<0.01).The apoptosis of NRCMs was induced by H2O2. Artificially inhibited BTEB gene expression with BTEB specific siRNA,BTEB mRNA and protein expression decreased obviously (P<0.05). Compared with control group, the apoptotic rates of NRCMs induced by H2O2in IGF-1 group and BTEB specific siRNA groups were declined (all P<0.05),decreased Caspase-3 activity(all P<0.05), attenuated DNA fragmentation and reduced apoptotic bodies were also observed in these groups. The anti-apoptotic effect of BTEB gene silencing on NRCMs was similar with that of IGF-1 treatment. Conclusion IGF-1 protects cardiomyocytes from apoptosis by down-regulating transcription factor BTEB through ERK1/2 pathway.