F-actin-binding domain of c-Abl regulates localized phosphorylation of C3G: role of C3G in c-Abl-mediated cell death
F-actin-binding domain of c-Abl regulates localized phosphorylation of C3G: role of C3G in c-Abl-mediated cell death
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DOI：
10.1038/onc.2010.113
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发表时间：
2010-08-12
期刊：
影响因子：
8
通讯作者：
Radha, V.
中科院分区：
文献类型：
--
作者：
Mitra, A.;Radha, V.
c-Abl酪氨酸激酶通过其调节细胞凋亡和肌动蛋白动力学的能力维持细胞内稳态。在体内，c-Abl活性受到严格调控，并且所涉及的机制尚未完全了解。在这里，我们确定了Rap 1鸟嘌呤核苷酸交换因子，C3 G（RapGEF 1），作为一个基板和c-Abl介导的功能的效应。哺乳动物细胞系中c-Abl的异位表达（已知可诱导细胞凋亡）导致Y504上内源性C3 G的磷酸化，与细胞脱离和染色质浓缩同时发生。磷酸化的C3 G正好与限制c-Abl激活在富含肌动蛋白的区域，并依赖于细胞的F-肌动蛋白动力学。与C3 G或c-Abl不同，p-C3 G对去污剂提取具有抗性，表明其对细胞骨架的亲和力增强。局部C3 G磷酸化和与细胞死亡的一致性依赖于c-Abl的F-actin-binding domain（FABD）。氧化应激激活内源性c-Abl与Y504上的细胞C3 G磷酸化相关。使用RNAi或显性负性方法抑制C3 G表达和功能可抑制c-Abl介导的细胞死亡。这些发现确定C3 G作为c-Abl的新靶点，并且还表明c-Abl的FABD对于调节其限制性激活以诱导凋亡是必需的。Oncogene（2010）29，4528-4542; doi：10.1038/onc.2010.113; 2010年6月28日在线发表
The c-Abl tyrosine kinase maintains cellular homeostasis through its ability to regulate apoptosis and actin dynamics. In vivo, c-Abl activity is stringently regulated and mechanisms involved are not fully understood. Here, we identified the Rap1 guanine nucleotide exchange factor, C3G (RapGEF1), as a substrate and an effector of c-Abl-mediated functions. Ectopic expression of c-Abl in mammalian cell lines, known to induce apoptosis, resulted in phosphorylation of endogenous C3G on Y504 coincident with cell detachment and chromatin condensation. Phosphorylation of C3G coincided with restricted c-Abl activation in regions rich in actin, and was dependent on cellular F-actin dynamics. Unlike C3G or c-Abl, p-C3G was resistant to detergent extraction, suggesting its enhanced affinity for the cytoskeleton. Localized C3G phosphorylation and coincidence with cells undergoing cell death was dependent on F-actin-binding domain (FABD) of c-Abl. Activation of endogenous c-Abl by oxidative stress was associated with phosphorylation of cellular C3G on Y504. Inhibition of C3G expression and function using RNAi or dominant-negative approaches inhibited c-Abl-mediated cell death. These findings identify C3G as a novel target of c-Abl and also show that FABD of c-Abl is essential for regulation of its restricted activation to induce apoptosis. Oncogene (2010) 29, 4528-4542; doi: 10.1038/onc.2010.113; published online 28 June 2010