权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Functional analysis of protein tyrosine phosphatase in the formation of retinotectal projection

蛋白酪氨酸磷酸酶在视网膜顶盖投射形成中的功能分析

基本信息

批准号：
17500243
负责人：
SHINTANI Takafumi
金额：
$ 1.92万
依托单位：
National Institute for Basic Biology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-17500243/
关键词：
retina tectum retinal axon projection protein phosphatase protein kinase tyrosine phosphorylation dephosphorylation

项目摘要

Eph receptors are the largest family of receptor-type tyrosine kinases (RTKs) and are classified into two groups, A-type (EphAs) and B-type (EphBs)^1. The Eph receptors are involved in numerous events such as cell movements, axonal guidance, formation of synapses, maintenance of synaptic plasticity, organization of cell boundaries, formation of the cardiovasculature system and carcinogenesis^2. Interaction of the Eph receptors with their ligands, the ephrins, requires cell-cell contact in vivo because both the receptor and the ligand are membrane-bound. Although there exist exceptions^<3,4>, EphA receptors preferentially bind the ephrin-As, which are attached to the plasma membrane through a glycosylphosphatidylinositol (GPI) anchor, and EphB receptors preferentially bind the transmembrane ephrin-Bs. Upon binding the ephrin ligands, Eph receptors are autophosphorylated at several tyrosine residues and subsequently activate signaling cascades downstream. However, protein tyrosine phosph … More atases (PTPs) responsible for the negative regulation of Eph have not been elucidated. Here, I identified protein tyrosine phosphatase receptor type O (Ptpro) as a PTP that dephosphorylates Eph receptors as substrates. In mammalian two-hybrid and immunoprecipitation assays, a substrate-trapping mutant of Ptpro formed stable complexes with EphA4 and EphB2 receptors. In vitro assays using GST-fused forms of Ptpro showed direct dephosphorylation of Eph receptors by Ptpro. Experiments with point-mutant constructs of EphA4 and EphB2 as well as those with phosphopeptides revealed that Ptpro dephosphorylates a phosphotyrosine residue conserved in the juxtamembrane region, which is required for the activation and signal transmission of Eph receptors. Using the chick retinotectal projection system, I show that Ptpro controls the sensitivity of retinal axons to ephrins and thereby has a crucial role in the establishment of topographic projections. My findings explain the molecular mechanism that determines the threshold of the response of Eph receptors to ephrins in vivo. Less

Eph 受体是最大的受体型酪氨酸激酶 (RTK) 家族，分为两组：A 型 (EphAs) 和 B 型 (EphBs)^1。 Eph 受体参与许多事件，例如细胞运动、轴突引导、突触形成、突触可塑性的维持、细胞边界的组织、心血管系统的形成和癌发生^2。 Eph 受体与其配体肝配蛋白的相互作用需要体内细胞与细胞的接触，因为受体和配体都是膜结合的。尽管存在例外^<3,4>，EphA受体优先结合肝配蛋白-A，肝配蛋白-A通过糖基磷脂酰肌醇(GPI)锚附着于质膜，并且EphB受体优先结合跨膜肝配蛋白-B。结合肝配蛋白配体后，Eph 受体在几个酪氨酸残基处发生自磷酸化，随后激活下游信号级联。然而，负责 Eph 负调节的蛋白酪氨酸磷酸酶 (PTP) 尚未阐明。在这里，我鉴定出 O 型蛋白酪氨酸磷酸酶受体 (Ptpro) 作为一种 PTP，可以作为底物使 Eph 受体去磷酸化。在哺乳动物双杂交和免疫沉淀测定中，Ptpro 的底物捕获突变体与 EphA4 和 EphB2 受体形成稳定的复合物。使用 GST 融合形式的 Ptpro 进行的体外测定表明，Ptpro 可以直接使 Eph 受体去磷酸化。对 EphA4 和 EphB2 点突变构建体以及磷酸肽构建体的实验表明，Ptpro 可使近膜区域保守的磷酸酪氨酸残基去磷酸化，这是 Eph 受体激活和信号传递所必需的。使用小鸡视网膜顶盖投影系统，我证明 Ptpro 控制视网膜轴突对肝配蛋白的敏感性，从而在地形投影的建立中发挥着至关重要的作用。我的研究结果解释了决定体内 Eph 受体对肝配蛋白反应阈值的分子机制。较少的