Multimolecular complex of Par-4 and E2F1 binding to Smac promoter contributes to glutamate-induced apoptosis in human- bone mesenchymal stem cells

• Published in: Nucleic acids research 2008-09, Vol.36 (15), p.5021-5032
• Main Authors: Lu, Chao, Chen, Jie-Qing, Zhou, Guo-Ping, Wu, Sheng-Hua, Guan, Ya-Fei, Yuan, Chuan-Shun
• Format: Article
• Language: English
• Subjects: Apoptosis; Apoptosis Regulatory Proteins - chemistry; Apoptosis Regulatory Proteins - metabolism; Apoptosis Regulatory Proteins - physiology; Binding Sites; Bone Marrow Cells - cytology; Cells, Cultured; E2F1 Transcription Factor - antagonists & inhibitors; E2F1 Transcription Factor - metabolism; Glutamic Acid - toxicity; Humans; Intracellular Signaling Peptides and Proteins - genetics; Mesenchymal Stromal Cells - cytology; Mesenchymal Stromal Cells - drug effects; Mesenchymal Stromal Cells - metabolism; Mitochondrial Proteins - biosynthesis; Mitochondrial Proteins - genetics; Molecular Biology; Promoter Regions, Genetic; Transcriptional Activation
• ISSN: 0305-1048; 1362-4962
• DOI: 10.1093/nar/gkn426

Neural cells undergo glutamate-induced apoptosis in ischaemic brain tissue, in which prostate apoptosis response-4 gene (Par-4) is involved. Human-bone mesenchymal stem cells can be utilized as an effective therapy for ischemic brain injury. In this study, we found that glutamate could induce apoptosis in human-bone mesenchymal stem cells, accompanied by increased expression of Par-4 gene and Smac release from mitochondria. Repressing Par-4 expression attenuated the glutamate-induced apoptosis. Both Par-4 protein and E2F1 protein could bind to E2F1-binding BS3 site on Smac promoter and participated in the formation of a proteins-DNA complex. Moreover, in the complex, E2F1, not Par-4, was found to be directly bound to the Smac promoter, suggesting that Par-4 exerted indirectly its transcriptional control on the Smac gene though interacting with E2F1. Expression of full-length Par-4 in human-bone mesenchymal cells resulted in increased activity of the Smac promoter. In addition, the indirect transcripional regulation of Par-4 on Smac depended on its COOH terminus-mediated interaction between Par-4 and E2F1. We conclude that the formation of proteins-DNA complex, containing Par-4 protein, E2F1 protein and the Smac promoter, contributes to the pro-apoptotic effect on glutamate-treated human-bone mesenchymal stem cells.