Cupidin, an Isoform of Homer/Vesl, Interacts with the Actin Cytoskeleton and Activated Rho Family Small GTPases and Is Expressed in Developing Mouse Cerebellar Granule Cells
Cupidin, an Isoform of Homer/Vesl, Interacts with the Actin Cytoskeleton and Activated Rho Family Small GTPases and Is Expressed in Developing Mouse Cerebellar Granule Cells
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DOI：
10.1523/jneurosci.19-19-08389.1999
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发表时间：
1999-10
期刊：
影响因子：
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通讯作者：
Y. Shiraishi;A. Mizutani;H. Bito;K. Fujisawa;S. Narumiya;K. Mikoshiba;T. Furuichi
中科院分区：
文献类型：
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作者：
Y. Shiraishi;A. Mizutani;H. Bito;K. Fujisawa;S. Narumiya;K. Mikoshiba;T. Furuichi
利用荧光差异显示策略从出生后小鼠小脑中分离出发育调节的Homer/Vesl亚型Cupidin （Homer 2a/Vesl-2Δ11）。大约在出生后第7天，在小脑颗粒细胞中检测到最强的Cupidin表达。丘比特苷在突触后密度部分富集，其免疫反应性在突触发生活跃时集中于内颗粒层肾小球。Cupidin蛋白可分为两个功能域：在Homer/Vesl家族蛋白中高度保守的n端结构域和包含多个亮氨酸拉链基序的c端结构域。在体外实验中，能够与代谢性谷氨酸受体1 （mGluR1）结合的Cupidin n端片段也能与F-actin相互作用。在培养的小脑颗粒细胞中，f -肌动蛋白与丘比特素免疫细胞化学共定位，并使用抗丘比特素抗体从粗小脑分离物中免疫沉淀丘比特素- mglur1 -肌动蛋白复合物。另一方面，在体外，Cupidin的c端部分以gtp依赖的方式与Rho家族小GTPases成员Cdc42结合，并且在异源表达系统中，Cupidin与活化的Cdc42功能相互作用。总之，我们的研究结果表明，Cupidin可能作为一种突触后支架蛋白，将mGluR信号与肌动蛋白细胞骨架和Rho家族蛋白连接起来，可能在小脑颗粒细胞突触形成过程中发生的形态变化的动态阶段。
A developmentally regulated Homer/Vesl isoform, Cupidin (Homer 2a/Vesl-2Δ11), was isolated from postnatal mouse cerebellum using a fluorescent differential display strategy. The strongest expression of Cupidin was detected in the cerebellar granule cells at approximately postnatal day 7. Cupidin was enriched in the postsynaptic density fraction, and its immunoreactivity was concentrated at glomeruli of the inner granular layer when active synaptogenesis occurred. Cupidin protein could be divided into two functional domains: the N-terminal portion, which was highly conserved among Homer/Vesl family proteins, and the C-terminal portion, which consisted of a putative coiled-coil structure, including several leucine zipper motifs. The N-terminal fragment of Cupidin, which was able to associate with metabotropic glutamate receptor 1 (mGluR1), also interacted with F-actin in vitro. In keeping with this, F-actin immunocytochemically colocalized with Cupidin in cultured cerebellar granule cells, and a Cupidin–mGluR1–actin complex was immunoprecipitated from crude cerebellar lysates using an anti-Cupidin antibody. On the other hand, the C-terminal portion of Cupidin bound to Cdc42, a member of Rho family small GTPases, in a GTP-dependent mannerin vitro, and Cupidin functionally interacted with activated-Cdc42 in a heterologous expression system. Together, our findings indicate that Cupidin may serve as a postsynaptic scaffold protein that links mGluR signaling with actin cytoskeleton and Rho family proteins, perhaps during the dynamic phase of morphological changes that occur during synapse formation in cerebellar granule cells.