Mechanical stretch induces mitochondria-dependent apoptosis in neonatal rat cardiomyocytes and G2/M accumulation in cardiac fibroblasts
Mechanical stretch induces mitochondria-dependent apoptosis in neonatal rat cardiomyocytes and G2/M accumulation in cardiac fibroblasts
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DOI：
10.1038/sj.cr.7290198
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发表时间：
2004-02-01
期刊：
影响因子：
44.1
通讯作者：
Chen, Q
中科院分区：
文献类型：
--
作者：
Liao, XD;Wang, XH;Chen, Q
在许多心脏疾病的情况下，由于异常的机械负荷，心脏重塑与心肌细胞的损失和纤维组织的增加有关。在本研究中，一个良好的描述在体外持续拉伸模型来研究机械拉伸诱导的反应，在新生心肌细胞和心脏成纤维细胞。心肌细胞（而非心脏成纤维细胞）经历了细胞色素a依赖性细胞凋亡，如细胞色素c（cyto c）和Smac/DIABLO从线粒体释放到胞质溶胶中所证明的，伴随着线粒体膜电位（Deltapsi（m））降低，表明线粒体通透性转换孔（PTP）打开。PTP抑制剂环孢菌素A（Cyclosporin A）可抑制牵张诱导的细胞胞质C释放、Deltapsi（m）减少和细胞凋亡，提示线粒体PTP在牵张诱导的细胞凋亡中起重要作用。拉伸还导致心肌细胞中促凋亡Bcl-2家族蛋白（包括Bax和Bad）的表达增加，但在成纤维细胞中没有。牵张后Bax在线粒体内大量积累。细胞渗透性Bid-BH 3肽可诱导和促进牵张诱导的心肌细胞凋亡和Deltapsi（m）减少。这些结果表明，Bcl-2家族蛋白在耦合拉伸信号线粒体死亡机制中发挥重要作用，可能是通过靶向PTP。有趣的是，p53的水平在牵张后12小时增加，尽管我们观察到Bax上调和凋亡早在1小时就发生了。腺病毒递送显性负性p53阻断心肌细胞中Bax上调，但对防止牵张诱导的细胞凋亡显示部分作用，表明p53仅部分参与介导牵张诱导的细胞凋亡。此外，我们发现p21上调，cyclin B1下调，仅在心脏成纤维细胞，这可能与G（2）/M积累的机械拉伸反应。
Heart remodeling is associated with the loss of cardiomyocytes and increase of fibrous tissue owing to abnormal mechanical load in a number of heart disease conditions. In present study, a well-described in vitro sustained stretch model was employed to study mechanical stretch-induced responses in both neonatal cardiomyocytes and cardiac fibroblasts. Cardiomyocytes, but not cardiac fibroblasts, underwent mitochondria-dependent apoptosis as evidenced by cytochrome c (cyto c) and Smac/DIABLO release from mitochondria into cytosol accompanied by mitochondrial membrane potential (Deltapsi(m)) reduction, indicative of mitochondrial permeability transition pore (PTP) opening. Cyclosporin A, an inhibitor of PTP, inhibited stretch-induced cyto c release, Deltapsi(m) reduction and apoptosis, suggesting an important role of mitochondrial PTP in stretch-induced apoptosis. The stretch also resulted in increased expression of the pro-apoptotic Bcl-2 family proteins, including Bax and Bad, in cardiomyocytes, but not in fibroblasts. Bax was accumulated in mitochondria following stretch. Cell permeable Bid-BH3 peptide could induce and facilitate stretch-induced apoptosis and Deltapsi(m) reduction in cardiomyocytes. These results suggest that Bcl-2 family proteins play an important role in coupling stretch signaling to mitochondrial death machinery, probably by targeting to PTP. Interestingly, the levels of p53 were increased at 12 h after stretch although we observed that Bax upregulation and apoptosis occurred as early as 1 h. Adenovirus delivered dominant negative p53 blocked Bax upregulation in cardiomyocytes but showed partial effect on preventing stretch-induced apoptosis, suggesting that p53 was only partially involved in mediating stretch-induced apoptosis. Furthermore, we showed that p21 was upregulated and cyclin B1 was downregulated only in cardiac fibroblasts, which may be associated with G(2)/M accumulation in response to mechanical stretch.