A truncated tropo-myosine-related kinase B receptor, T1, regulates glial cell morphology via rho GDP dissociation inhibitor 1
A truncated tropo-myosine-related kinase B receptor, T1, regulates glial cell morphology via rho GDP dissociation inhibitor 1
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DOI：
10.1523/jneurosci.4436-04.2005
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发表时间：
2005-02-09
影响因子：
5.3
通讯作者：
Hayashi, M
中科院分区：
文献类型：
--
作者：
Ohira, K;Kumanogoh, H;Hayashi, M
脑源性神经营养因子（brain-derived neurotrophic factor，BDNF）通过与原肌氨酸相关激酶B（Trk B）受体的结合，发挥神经存活、分化和可塑性等多种生物学功能。T1是缺乏酪氨酸激酶的TrkB受体的同种型，在成年哺乳动物CNS中占主导地位，但其作用仍有争议。在这项研究中，为了检查T1是否转导信号并确定其功能，我们首先用T1特异性C末端肽对T1结合蛋白进行亲和纯化，并鉴定了Rho GDP解离抑制剂1（GDI 1），一种Rho小G蛋白的GDP解离抑制剂，作为与T1直接相关的信号蛋白。BDNF与T1的结合导致Rho GDI 1从T1的C-末端尾部解离。培养30 d的星形胶质细胞只表达内源性BDNF受体T1。在培养30 d的星形胶质细胞中，Rho GDI 1以BDNF依赖的方式解离时，控制Rho GTPases的活性，从而导致星形胶质细胞形态的快速变化。此外，使用2天培养的星形胶质细胞转染T1，T1缺失突变体，或青色荧光蛋白融合蛋白的T1特异性的C-末端序列，我们证明了T1- Rho GDI 1信号是必不可少的调节活动的Rho GTPases和星形胶质细胞之间的后续形态学变化。因此，这些发现表明，T1信号级联可以通过调节Rho GT3活性来改变星形胶质细胞的形态。
Through tropo-myosine-related kinase B (TrkB) receptors, brain-derived neurotrophic factor ( BDNF) performs many biological functions such as neural survival, differentiation, and plasticity. T1, an isoform of TrkB receptors that lacks a tyrosine kinase, predominates in the adult mammalian CNS, yet its role remains controversial. In this study, to examine whether T1 transduces a signal and to determine its function, we first performed an affinity purification of T1-binding protein with the T1- specific C-terminal peptide and identified Rho GDP dissociation inhibitor 1 ( GDI1), a GDP dissociation inhibitor of Rho small G-proteins, as a signaling protein directly associated with T1. The binding of BDNF to T1 caused Rho GDI1 to dissociate from the C-terminal tail of T1. Astrocytes cultured for 30 d expressed only endogenous T1 among the BDNF receptors. In 30 d cultured astrocytes, Rho GDI1, when dissociated in a BDNF-dependent manner, controlled the activities of the Rho GTPases, which resulted in rapid changes in astrocytic morphology. Furthermore, using 2 d cultured astrocytes that were transfected with T1, a T1 deletion mutant, or cyan fluorescent protein fusion protein of the T1- specific C-terminal sequence, we demonstrated that T1- Rho GDI1 signaling was indispensable for regulating the activities of Rho GTPases and for the subsequent morphological changes among astrocytes. Therefore, these findings indicate that the T1 signaling cascade can alter astrocytic morphology via regulation of Rho GTPase activity.