RhoA/Rho kinase up-regulate bax to activate a mitochondrial death pathway and induce cardiomyocyte apoptosis
RhoA/Rho kinase up-regulate bax to activate a mitochondrial death pathway and induce cardiomyocyte apoptosis
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DOI：
10.1074/jbc.m604298200
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发表时间：
2007-03-16
影响因子：
4.8
通讯作者：
Brown, Joan Heller
中科院分区：
文献类型：
--
作者：
Del Re, Dominic P.;Miyamoto, Shigeki;Brown, Joan Heller
小 G 蛋白 RhoA 调节肌动蛋白细胞骨架，其参与细胞增殖也已被证实。相比之下，人们对 RhoA 是否参与细胞存活或凋亡知之甚少。在体外的心肌细胞中，RhoA 诱导肥大细胞生长和基因表达。然而，在体内，RhoA 表达导致心力衰竭的发生（Sah, V. P., Minamisawa, S., Tam, S. P., Wu, T. H., Dorn, G. W., Ross, J. Jr., Chien, K. R., and Brown, J. H. (1999) J. Clin. Investig. 103, 1627-1634），这是一种与心肌细胞广泛相关的病症细胞凋亡。我们在此证明，心肌细胞中激活的 RhoA 的腺病毒过度表达会诱导心肌细胞肥大，并随着时间的推移转变为细胞凋亡，半胱天冬酶激活和核小体 DNA 片段化证明了这一点。 Rho 激酶抑制剂 Y-27632 和 HA-1077 以及显性失活 Rho 激酶的表达可阻断这些反应。 Caspase-9（而非 caspase-8）被激活，其抑制作用可防止 DNA 断裂，这与线粒体死亡途径的参与一致。有趣的是，RhoA 表达诱导促凋亡 Bcl-2 家族蛋白 Bax 上调 3-4 倍。 RhoA 还可以增加活化的 Bax 水平以及位于线粒体的 Bax 蛋白的量。 Bax mRNA 被 RhoA 增加，表明转录调节，显性失活 p53 突变体阻断 Bax 上调的能力表明 p53 参与了这种反应。通过用 Bax 抑制肽处理来检查 Bax 在 RhoA 诱导的细胞凋亡中的参与情况，发现该肽可显着减弱 DNA 断裂以及 caspase-9 和 -3 的激活。显性失活 p53 还可以防止 RhoA 诱导的细胞凋亡。我们得出结论，RhoA/Rho 激酶激活通过 p53 上调 Bax，从而诱导线粒体死亡途径和心肌细胞凋亡。
The small G-protein RhoA regulates the actin cytoskeleton, and its involvement in cell proliferation has also been established. In contrast, little is known about whether RhoA participates in cell survival or apoptosis. In cardiomyocytes in vitro, RhoA induces hypertrophic cell growth and gene expression. In vivo, however, RhoA expression leads to development of heart failure (Sah, V. P., Minamisawa, S., Tam, S. P., Wu, T. H., Dorn, G. W., Ross, J. Jr., Chien, K. R., and Brown, J. H. (1999) J. Clin. Investig. 103, 1627-1634), a condition widely associated with cardiomyocyte apoptosis. We demonstrate here that adenoviral overexpression of activated RhoA in cardiomyocytes induces hypertrophy, which transitions over time to apoptosis, as evidenced by caspase activation and nucleosomal DNA fragmentation. The Rho kinase inhibitors Y-27632 and HA-1077 and expression of a dominant negative Rho kinase block these responses. Caspase-9, but not caspase-8, is activated, and its inhibition prevents DNA fragmentation, consistent with involvement of a mitochondrial death pathway. Interestingly, RhoA expression induces a 3-4-fold up-regulation of the proapoptotic Bcl-2 family protein Bax. RhoA also increases levels of activated Bax and the amount of Bax protein localized at mitochondria. Bax mRNA is increased by RhoA, indicating transcriptional regulation, and the ability of a dominant negative p53 mutant to block Bax up-regulation implicates p53 in this response. The involvement of Bax in RhoA-induced apoptosis was examined by treatment with a Bax-inhibitory peptide, which was found to significantly attenuate DNA fragmentation and caspase-9 and -3 activation. The dominant negative p53 also prevents RhoA-induced apoptosis. We conclude that RhoA/Rho kinase activation up-regulates Bax through p53 to induce a mitochondrial death pathway and cardiomyocyte apoptosis.