Two GTPases, cdc42 and rac, bind directly to a protein implicated in the immunodeficiency disorder Wiskott-Aldrich syndrome
Two GTPases, cdc42 and rac, bind directly to a protein implicated in the immunodeficiency disorder Wiskott-Aldrich syndrome
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DOI：
10.1016/s0960-9822(02)00423-2
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发表时间：
1996-01-01
期刊：
影响因子：
9.2
通讯作者：
Hall, A
中科院分区：
文献类型：
--
作者：
Aspenstrom, P;Lindberg, U;Hall, A
背景：Rho家族的小分子GTP酶在控制动物细胞的运动行为中起着重要的作用。具体地说，Cdc42和Pac已被证明分别诱导在瑞士3T3成纤维细胞的细胞外周形成丝状伪足和片状伪足。此外，这两种GTP酶都是细胞周期G(1)期所必需的，可能是通过调节Jun N末端激酶(JNK)信号通路的活性来实现的，为了更紧密地研究Rho GTP酶在哺乳动物细胞中不同功能的机制，我们寻找了这些蛋白的下游靶标。结果：酵母双杂交筛选与人CDC42 GTP酶相互作用的蛋白质鉴定出WASP，一种与免疫缺陷疾病Wiskott-Aldrich综合征(Wiskott-Aldrich综合征)有关的蛋白质。在大肠杆菌中表达的重组WASP也与CDC42结合，与Pac弱结合，但不与Rho结合。Cdc42/Rac结合区位于WASP的201-321位氨基酸之间，结合依赖于Cdc42和Pac的GTP结合构象。此外，WASP不催化CDc42上GTP酶的激活或核苷酸交换活性。结论：定位克隆可能与WASP引起IS有关，且该蛋白在患者体内存在缺陷。WASP仅在造血系的细胞中表达，来自AS患者的淋巴细胞具有扭曲的细胞表面，并显示出增殖能力降低。最近发现黄蜂与适配蛋白Nck的Src同源3(SH3)结构域结合。这一观察结果表明，Was是由CDC4a/Rac和Nck调控的信号转导通路缺陷所致。
Background: Members of the Rho family of small GTPases play an essential role in controlling the motile behaviour of animal cells. Specifically, Cdc42 and Pac have been shown to induce the formation of filopodia and lamellipodia, respectively, at the cell periphery of Swiss 3T3 fibroblasts. In addition, both GTPases are required for progression through G(1) phase of the cell cycle, possibly by regulating the activity of the Jun N-terminal kinase (JNK) signalling pathway, In order to examine more closely the mechanisms underlying the diverse functions of Rho GTPases in mammalian cells, we searched for downstream targets of these proteins.Results: A yeast two-hybrid screen for proteins interacting with the human Cdc42 GTPase identified WASP, a protein implicated in the immunodeficiency disorder Wiskott-Aldrich syndrome (WAS). Recombinant WASP, expressed in Escherichia coli, also bound to Cdc42 and weakly to Pac, but not at all to Rho. The Cdc42/Rac-binding domain was identified in a region between amino acids 201-321 of WASP, and binding was dependent on Cdc42 and Pac being in the GTP-bound conformation. Furthermore, WASP did not catalyze GTPase activation or nucleotide exchange activity on Cdc42.Conclusions: Positional cloning has implicated WASP in causing WAS, and the protein is defective in patients suffering from the disease. WASP is expressed exclusively in cells of hematopoietic lineage, and lymphocytes from WAS patients have a distorted cell-surface and exhibit reduced proliferative capacity. WASP has recently been found to bind to the Src-homology 3 (SH3) domain of the adapter protein Nck. This observation, and the results presented here, suggest that WAS is the result of defects in signal transduction pathways regulated by Cdc4a/Rac and Nck.