Small GTPase Tc10 and its homologue RhoT induce N-WASP-mediated long process formation and neurite outgrowth
Small GTPase Tc10 and its homologue RhoT induce N-WASP-mediated long process formation and neurite outgrowth
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DOI：
10.1242/jcs.00208
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发表时间：
2003-01-01
影响因子：
4
通讯作者：
Endo, T
中科院分区：
文献类型：
--
作者：
Abe, T;Kato, M;Endo, T
Rho家族小GTP酶通过肌动蛋白细胞骨架的重组调节多种细胞功能。其中，Cdc42和Tc10在培养的细胞中诱导丝状伪足或外周突起。我们已经确定了该家族的一个成员，命名为RhoT，与Tc10密切相关。Tc10在肌组织和脑组织中表达，在C2骨骼肌细胞分化和PC12、N1E-115细胞向神经元分化过程中有明显的诱导作用。另一方面，RhoT主要在心脏和子宫中表达，并在N1E-115细胞的神经元分化过程中被诱导。Tc10外源性表达的成纤维细胞产生肌动蛋白丝的周边过程比Cdc42形成的丝状伪足长，而RhoT产生更长，更厚的过程中含有肌动蛋白丝。此外，Tc10和RhoT都诱导PC12和N1E-115细胞中的神经突生长，但Cdc42本身没有这样做。Tc10和RhoT以及Cdc42与N-WASP的N-末端CRIB基序结合并激活N-WASP以诱导Arp2/3复合物介导的肌动蛋白聚合。Tc10和RhoT诱导的外周突起和神经突的形成被N-WASP的显性失活突变体的共表达所阻止。因此，N-WASP对于Tc10和RhoT诱导的突起形成和神经突生长是必需的。显性负调控的Cdc42、Tc10和RhoT分别抑制了二丁酰环腺苷酸和血清饥饿诱导的PC12和N1E-115细胞的神经元分化。总的来说，所有这些Rho家族蛋白都是神经元分化所必需的，但它们在突起形成和轴突延伸中发挥不同的功能。因此，N-WASP激活这些小GTP酶介导的神经元分化，除了最近确定的作用，在葡萄糖摄取。
Rho family small GTPases regulate multiple cellular functions through reorganization of the actin cytoskeleton. Among them, Cdc42 and Tc10 induce filopodia or peripheral processes in cultured cells. We have identified a member of the family, designated as RhoT, which is closely related to Tc10. Tc10 was highly expressed in muscular tissues and brain and remarkably induced during differentiation of C2 skeletal muscle cells and neuronal differentiation of PC12 and N1E-115 cells. On the other hand, RhoT was predominantly expressed in heart and uterus and induced during neuronal differentiation of N1E-115 cells. Tc10 exogenously expressed in fibroblasts generated actin-filament-containing peripheral processes longer than the Cdc42-formed filopodia, whereas RhoT produced much longer and thicker processes containing actin filaments. Furthermore, both Tc10 and RhoT induced neurite outgrowth in PC12 and N1E-115 cells, but Cdc42 did not do this by itself. Tc10 and RhoT as well as Cdc42 bound to the N-terminal CRIB-motif-containing portion of N-WASP and activated N-WASP to induce Arp2/3-complex-mediated actin polymerization. The formation of peripheral processes and neurites by Tc10 and RhoT was prevented by the coexpression of dominant-negative mutants of N-WASP Thus, N-WASP is essential for the process formation and neurite outgrowth induced by Tc10 and RhoT. Neuronal differentiation of PC12 and N1E-115 cells induced by dibutyryl cyclic AMP and by serum starvation, respectively, was prevented by dominant-negative Cdc42, Tc10 and RhoT. Taken together, all these Rho family proteins are required for neuronal differentiation, but they exert their functions differentially in process formation and neurite extension. Consequently, N-WASP activated by these small GTPases mediates neuronal differentiation in addition to its recently identified role in glucose uptake.