The Traf2- and Nck-interacting kinase as a putative effector of Rap2 to regulate actin cytoskeleton
The Traf2- and Nck-interacting kinase as a putative effector of Rap2 to regulate actin cytoskeleton
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DOI：
10.1074/jbc.m406370200
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发表时间：
2004-11-19
影响因子：
4.8
通讯作者：
Kariya, K
中科院分区：
文献类型：
--
作者：
Taira, K;Umikawa, M;Kariya, K
Rap 2属于Ras家族的小GTP结合蛋白，但其在细胞信号传导中的具体作用仍然未知。在本研究中，我们从大鼠脑中亲和纯化了一个与Rap 2相互作用的蛋白，分子量为155 kDa，p155。通过液相色谱串联质谱，我们已经确定p155为Traf 2和Nck相互作用激酶（TNIK）。TNIK具有与STE 20同源的N-末端激酶结构域，酿酒酵母促分裂原活化蛋白激酶，和被称为Citron同源（CNH）结构域的C-末端调节结构域。TNIK诱导F-肌动蛋白结构的破坏，从而抑制细胞铺展。此外，TNIK特异性激活c-Jun N-末端激酶（JNK）通路。在我们的观察中，TNIK通过其CNH结构域与Rap 2相互作用，但不与Rap 1或Ras相互作用。TNIK与Rap 2的相互作用依赖于Rap 2的完整效应区和GTP结合构型。当在培养的细胞中共表达时，TNIK与Rap 2共定位，而缺乏CNH结构域的突变体TNIK则没有。Rap 2有效地增强了TNIK对细胞铺展的抑制功能，但这在缺乏CNH结构域的突变TNIK中没有观察到。Rap 2没有显着增强TNIK诱导的JNK激活，但促进TNIK的自磷酸化和易位到洗涤剂不溶性的细胞骨架部分。这些结果表明TNIK是Rap 2调节肌动蛋白细胞骨架的特异性效应子。
Rap2 belongs to the Ras family of small GTP-binding proteins, but its specific roles in cell signaling remain unknown. In the present study, we have affinity-purified from rat brain a Rap2-interacting protein of similar to155 kDa, p155. By liquid chromatography tandem mass spectrometry, we have identified p155 as Traf2- and Nck-interacting kinase (TNIK). TNIK possesses an N-terminal kinase domain homologous to STE20, the Saccharomyces cerevisiae mitogen-activated protein kinase kinase kinase kinase, and a C-terminal regulatory domain termed the citron homology (CNH) domain. TNIK induces disruption of F-actin structure, thereby inhibiting cell spreading. In addition, TNIK specifically activates the c-Jun N-terminal kinase (JNK) pathway. Among our observations, TNIK interacted with Rap2 through its CNH domain but did not interact with Rap1 or Ras. TNIK interaction with Rap2 was dependent on the intact effector region and GTP-bound configuration of Rap2. When co-expressed in cultured cells, TNIK colocalized with Rap2, while a mutant TNIK lacking the CNH domain did not. Rap2 potently enhanced the inhibitory function of TNIK against cell spreading, but this was not observed for the mutant TNIK lacking the CNH domain. Rap2 did not significantly enhance TNIK-induced JNK activation, but promoted autophosphorylation and translocation of TNIK to the detergent-insoluble cytoskeletal fraction. These results suggest that TNIK is a specific effector of Rap2 to regulate actin cytoskeleton.