Regulation of actin cytoskeleton by mDab1 through N-WASP and ubiquitination of mDab1
Regulation of actin cytoskeleton by mDab1 through N-WASP and ubiquitination of mDab1
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DOI：
10.1042/bj20041103
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发表时间：
2004-11-15
影响因子：
4.1
通讯作者：
Takenawa, T
中科院分区：
文献类型：
--
作者：
Suetsugu, S;Tezuka, T;Takenawa, T
细胞的迁移对中枢神经系统的发育至关重要。从具有大脑多层结构缺陷的reeler突变小鼠中鉴定出的Reelin被认为是一种关键的信号分子，其作用是确定细胞位置的线索。mDab 1（小鼠失活同源物1）在Reelin下游起作用。然而，mDab 1在脑发育过程中调节细胞迁移的机制尚不清楚。在本文中，我们表明，mDab 1协会与N-WASP（神经元Wiskott-Aldrich综合征蛋白）在体外和胚胎小鼠的大脑。mDab 1直接激活N-WASP，并通过Arp 2/3（actin-related protein 2/3）复合物诱导肌动蛋白聚合。mDab 1在COS-7细胞中过表达时诱导丝状伪足的形成。这种丝状伪足的形成依赖于N-WASP，因为不能诱导Arp 2/3复合物介导的肌动蛋白聚合的N-WASP突变体的表达抑制了丝状伪足的形成。mDab 1的PTB（磷酸酪氨酸结合）结构域通过靠近N-WASP的CRIB（Cdc 42/Rac相互作用结合）基序的NRFY（Asn-Arg-Phe-Tyr）序列与N-WASP结合并在体外激活N-WASP。在COS-7细胞中，当mDab 1被Fyn激酶磷酸化时，mDab 1以Cbl依赖的方式被泛素化，并且mDab 1在活化的Fyn存在下不诱导丝状伪足。这些发现表明，mDab 1调节肌动蛋白细胞骨架通过N-WASP，这是负调控磷酸化介导的泛素化的mDab 1。
Migration of cells is critical to development of the central nervous system. Reelin, which was identified from the reeler mutant mice having a defect in the multilamellar structure of the brain, is thought to be a key signalling molecule that functions as a cue for determination of cell position. mDab1 (mouse Disabled homologue 1) functions downstream of Reelin. However, the mechanism by which mDab1 regulates cell migration during brain development is unknown. In the present paper, we show that mDab1 associates with N-WASP (neuronal Wiskott-Aldrich syndrome protein) in vitro and in brains of embryonic mice. mDab1 activates N-WASP directly, and induces actin polymerization through the Arp2/3 (actin-related protein 2/3) complex. mDab1 induces formation of filopodia when it is overexpressed in COS-7 cells. This filopodium formation is dependent on N-WASP, because expression of an N-WASP mutant that cannot induce Arp2/3-complex-mediated actin polymerization suppressed filopodium formation. The PTB (phosphotyrosine-binding) domain of mDab1 binds to N-WASP via the NRFY (Asn-Arg-Phe-Tyr) sequence close to the CRIB (Cdc42/Rac-interactive binding) motif of N-WASP and activates N-WASP in vitro. When mDab1 is phosphorylated by Fyn kinase in COS-7 cells, mDab1 is ubiquitinated in a Cbl-dependent manner, and mDab1 does not induce filopodium in the presence of activated Fyn. These findings suggest that mDab1 regulates the actin cytoskeleton through N-WASP, which is negatively regulated by phosphorylation-mediated ubiquitination of mDab1.