Dok-5 is involved in cardiomyocyte differentiation through PKB/FOXO3a pathway

Wen, Jianyan; Xia, Qing; Wang, Cheng; Liu, Wei; Chen, Yang; Gao, Jing; Gong, Yanhua; Yin, Bin; Ke, Yuannan; Qiang, Boqin; Yuan, Jiangang; Peng, Xiaozhong

doi:10.1016/j.yjmcc.2009.09.015

« Previous Next »Journal of Molecular and Cellular Cardiology
Volume 47, Issue 6 , Pages 761-769, December 2009

Dok-5 is involved in cardiomyocyte differentiation through PKB/FOXO3a pathway

Jianyan Wen
- National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China
- National Integrative Medicine Center for Cardiovascular Disease, China-Japan Friendship Hospital, Beijing 100029, China
- These authors contributed equally.
Qing Xia
- Department of Molecular Immunology, Beijing Institute of Basic Medical Science, Beijing 100850, China
- These authors contributed equally.
Cheng Wang
- Department of Physiology and Pathophysiology, Peking University Health Science Center, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing 100191, China
Wei Liu
- National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China
Yang Chen
- National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China
Jing Gao
- National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China
Yanhua Gong
- National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China
Bin Yin
- National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China
Yuannan Ke
- National Integrative Medicine Center for Cardiovascular Disease, China-Japan Friendship Hospital, Beijing 100029, China
Boqin Qiang
- National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China
Jiangang Yuan
- National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China
- Corresponding authors. Tel.: +86 10 65296411; fax: +86 10 65240529.
Xiaozhong Peng
- National Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China
- Corresponding authors. Tel.: +86 10 65296411; fax: +86 10 65240529.

Received 8 April 2009; received in revised form 20 September 2009; accepted 23 September 2009. published online 05 October 2009.

Abstract

The insulin receptor substrate (IRS) family plays important roles in cellular growth, signaling, and survival in the brain. We identified IRS6/Dok-5, a member of the IRS family, also expressed in heart. Dok-5 expression level significantly increased during cardiomyocyte differentiation of P19CL6 cells. To understand the mechanism of Dok-5 gene expression and regulation during cardiomyocyte differentiation, we first mapped the transcription start site of the mouse Dok-5 gene and characterized its promoter regions. Truncation and mutation analysis of the Dok-5 promoter identified the forkhead binding element responsible for the repression of Dok-5 promoter activation. The co-localization of FOXO3a and Dok-5 in the mouse heart allows FOXO3a to be a transcriptional regulator of Dok-5. Electrophoretic mobility shift assay and chromatin immunoprecipitation assay confirmed that FOXO3a could bind to the Dok-5 promoter, accompanied by FOXO3a translocation from the nucleus to cytoplasm. FOXO3a overexpression could inhibit Dok-5 promoter activity. Silencing FOXO3a expression by siRNA upregulated the expression of Dok-5 and enhanced cardiomyocyte differentiation. Moreover, Dok-5 siRNA attenuated cardiomyocyte differentiation. Our results provide the first evidence that FOXO3a, the PI3K/PKB downstream substrate, acts as a transcriptional repressor to inhibit the expression of Dok-5. Dok-5 is involved in cardiomyocyte differentiation by a PI3K/PKB/FOXO3a signaling pathway.

Keywords: Dok-5, FOXO3a, P19CL6, Cardiomyocyte differentiation