Membrane targeting of WAVE2 is not sufficient for WAVE2-dependent actin polymerization: a role for IRSp53 in mediating the interaction between Rac and WAVE2
Membrane targeting of WAVE2 is not sufficient for WAVE2-dependent actin polymerization: a role for IRSp53 in mediating the interaction between Rac and WAVE2
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DOI：
10.1242/jcs.010272
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发表时间：
2008-02-01
影响因子：
4
通讯作者：
Cox, Dianne
中科院分区：
文献类型：
--
作者：
Abou-Kheir, Wassim;Isaac, Beth;Cox, Dianne
Wiskott-Aldrich综合征蛋白（WASP）家族verprolin同源（WAVE）蛋白在Rac诱导的肌动蛋白动力学中起主要作用，但Rac不直接与WAVE蛋白结合。已经提出胰岛素受体底物蛋白53（IRSp 53）或含有Abelson相互作用蛋白1（Abi 1）的蛋白质复合物介导WAVE 2和Rac的相互作用。在RAW/LR 5巨噬细胞系中通过RNA介导的干扰（RNAi）耗尽内源性IRSp 53导致Rac 1 Q61 L诱导的表面皱褶和集落刺激因子1（CSF-1）诱导的肌动蛋白聚合、突起和细胞迁移显著减少。然而，IRSp 53对于Fc γ-R介导的吞噬作用、足体的形成或Cdc 42 V12诱导的丝状伪足的形成不是必需的。在RAW/LR 5细胞中，IRSp 53以Rac 1激活依赖的方式与WAVE 2和Abi 1形成免疫沉淀复合物。重要的是，内源性IRSp 53的减少或缺乏WAVE 2结合位点的IRSp 53的表达（IRSp 53 Δ SH 3）导致Rac 1与WAVE 2和Abi 1的缔合显著减少，表明Rac 1与WAVE 2和Abi 1的缔合是IRSp 53依赖性的。虽然已经提出WAVE 2活性受膜募集调节，但RAW/LR 5和Cos-7细胞中WAVE 2的膜靶向并不诱导肌动蛋白聚合或突出，表明膜募集不足以调节WAVE 2。总而言之，这些数据表明IRSp 53在体内将Rac 1与WAVE 2连接起来，其功能对于巨噬细胞中CSF-1诱导的富含F-肌动蛋白的突起和细胞迁移的产生至关重要。这项研究表明，Rac 1，沿着IRSp 53和Abi 1，参与了一个更复杂和更严格的调节WAVE 2比一个单独通过膜定位操作。
Wiskott-Aldrich syndrome protein (WASP)-family verprolin homologous ( WAVE) proteins play a major role in Rac-induced actin dynamics, but Rac does not bind directly to WAVE proteins. It has been proposed that either the insulin receptor substrate protein 53 (IRSp53) or a complex of proteins containing Abelson interactor protein 1 (Abi1) mediates the interaction of WAVE2 and Rac. Depletion of endogenous IRSp53 by RNA-mediated interference (RNAi) in a RAW/LR5 macrophage cell line resulted in a significant reduction of Rac1Q61L-induced surface ruffles and colony-stimulating factor 1 (CSF-1)-induced actin polymerization, protrusion and cell migration. However, IRSp53 was not essential for Fc gamma-R-mediated phagocytosis, formation of podosomes or for formation of Cdc42V12-induced filopodia. IRSp53 was found to be present in an immunoprecipitable complex with WAVE2 and Abi1 in a Rac1-activation-dependent manner in RAW/LR5 cells in vivo. Importantly, reduction of endogenous IRSp53 or expression of IRSp53 lacking the WAVE2-binding site (IRSp53 Delta SH3) resulted in a significant reduction in the association of Rac1 with WAVE2 and Abi1, indicating that the association of Rac1 with WAVE2 and Abi1 is IRSp53 dependent. While it has been proposed that WAVE2 activity is regulated by membrane recruitment, membrane targeting of WAVE2 in RAW/LR5 and Cos-7 cells did not induce actin polymerization or protrusion, suggesting that membrane recruitment was insufficient for regulation of WAVE2. Combined, these data suggest that IRSp53 links Rac1 to WAVE2 in vivo and its function is crucial for production of CSF-1-induced F-actin-rich protrusions and cell migration in macrophages. This study indicates that Rac1, along with IRSp53 and Abi1, is involved in a more complex and tight regulation of WAVE2 than one operating solely through membrane localization.