Phosphorylation of ERM proteins at filopodia induced by Cdc42
Phosphorylation of ERM proteins at filopodia induced by Cdc42
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DOI：
10.1046/j.1365-2443.2000.00348.x
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发表时间：
2000-07-01
期刊：
影响因子：
2.1
通讯作者：
Kaibuchi, K
中科院分区：
文献类型：
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作者：
Nakamura, N;Oshiro, N;Kaibuchi, K
背景：ERM(Ezrin、Radixin和Moesin)蛋白作为膜-细胞骨架连接物，已知定位于丝状足细胞和微绒毛样结构。我们发现Rho相关激酶(Rho-Kinase)/韩国α/ROCK II在Rho下游的Thr-558位使Moesin磷酸化，而这种磷酸化对微绒毛样结构的形成至关重要(Oshio，N.，Fukata，Y.&Kaibuhi，K.(1998)Rho相关激酶对Moesin的磷酸化在微绒毛样结构的形成中起着关键作用。J.Biol.化学。273、34663-34666)。然而，ERM蛋白在丝状伪足形成中的作用还不是很清楚。结果：我们利用识别COOH(C)末端苏氨酸磷酸化的ERM蛋白的抗体，检测了在CdC42诱导的丝状伪足形成过程中ERM的磷酸化状态。在NIH3T3细胞中，当有活性的Cdc42(V12)被导入NIH 3T3细胞后，丝状伪足的形成和丝状伪足顶端苏氨酸的ERM的磷酸化出现，而对照组ERM的磷酸化水平较低，并且磷酸化的ERM分布于细胞质中。我们还发现，强直性肌营养不良相关的CDC42结合蛋白结合蛋白(MRCK)是CDC42的效应蛋白，在无细胞系统中使C端苏氨酸上的Moesin磷酸化。共表达优势负性形式的MRCK可抑制C端苏氨酸磷酸化的ERM蛋白在C端丝足的形成。结论：CDC42诱导丝足的形成伴随着ERM蛋白的磷酸化，MRCK是丝足ERM蛋白磷酸化的候选蛋白。
Background: ERM (ezrin, radixin, and moesin) proteins function as membrane-cytoskeletal linkers, and are known to be localized at filopodia and microvilli-like structures. We have shown that Rho-associated kinase (Rho-kinase)/ROK alpha/ROCK II phosphorylates moesin at Thr-558 at the lower stream of Rho, and the phosphorylation is crucial to the formation of microvilli-like structures (Oshiro, N., Fukata, Y. & Kaibuchi, K. (1998) Phosphorylation of moesin by Rho-associated kinase (Rho-kinase) plays a crucial role in the formation of microvilli-like structures. J. Biol. Chem. 273, 34663- 34666). However, the role of ERM proteins in the formation of filopodia is less well characterized.Results: Here we examined the phosphorylation state of ERM during filopodia formation induced by Cdc42 using the antibody recognizing ERM proteins phosphorylated at COOH (C)-terminal threonine. When NIH 3T3 cells were transfected with constitutively active Cdc42 (Cdc42(V12)), filopodia formation was induced and phosphorylation of ERM at C-terminal threonine was observed at the tip of filopodia, while the phosphorylation levels of ERM were lower and phosphorylated ERM was distributed throughout the cytoplasm in the control cells. We also showed that Myotonic dystrophy kinase-related Cdc42-binding kinase (MRCK) which has been identified as an effector of Cdc42, phosphorylated moesin at C-terminal threonine in a cell-free system. Coexpression of the dominant negative form of MRCK inhibited both the formation of filopodia and accumulation of C-terminal threonine-phosphorylated ERM proteins at filopodia induced by Cdc42(V12).Conclusion: The formation of filopodia induced by Cdc42 is accompanied by phosphorylation of ERM proteins, and MRCK is a candidate for the kinase that phosphorylates ERM proteins at filopodia.