Heart of glass anchors Rasip1 at endothelial cell-cell junctions to support vascular integrity.
Heart of glass anchors Rasip1 at endothelial cell-cell junctions to support vascular integrity.
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DOI：
10.7554/elife.11394
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发表时间：
2016-01-19
期刊：
影响因子：
7.7
通讯作者：
Ginsberg MH
中科院分区：
文献类型：
--
作者：
de Kreuk BJ;Gingras AR;Knight JD;Liu JJ;Gingras AC;Ginsberg MH
玻璃心（Heart of Glass，HEG 1）是一种跨膜受体，Rasip 1是一种内皮特异性Rap 1结合蛋白，两者对心血管发育至关重要。在这里，我们进行了一个新的HEG 1相互作用蛋白质组学筛选和报告，HEG 1直接结合到Rasip 1。rasip 1定位于形成内皮细胞（EC）细胞-细胞连接，而沉默HEG 1可防止这种定位。相反，靶向HEG 1的Rasip 1在细胞中重新定位到线粒体。HEG 1中的Rasip 1结合位点包含9个残基序列，其缺失消除了HEG 1募集Rasip 1的能力。HEG 1与Rasip 1的中心区域结合，该结构域的缺失消除了Rasip 1结合HEG 1、易位至EC连接、抑制ROCK活性和维持EC连接完整性的能力。这些研究证实，HEG 1与Rasip 1的结合介导Rasip 1依赖于Rap 1的募集和EC细胞-细胞连接的稳定。DOI：http://dx.doi.org/10.7554/eLife.11394.001血管里排列着被称为血管内皮细胞的细胞。这些细胞在由几种不同蛋白质组成的连接处彼此连接。这些连接有助于控制血管的发育方式，并提供一个屏障来控制水和某些其他分子通过血管壁的运动。这种屏障在败血症和动脉粥样硬化等疾病中变得薄弱。心脏和血管正常发育所必需的两种蛋白质被称为“玻璃心”（HEG 1）和Rasip 1。虽然已经鉴定出在细胞连接处与HEG 1结合的蛋白质，但这种结合仅涉及HEG 1的一小部分区域。这导致de Kreuk，Gingras等人寻找与HEG 1相互作用的其他蛋白质，这可能对控制血管的发育很重要。这表明HEG 1直接与Rasip 1结合。进一步的实验表明，HEG 1对于将Rasip 1靶向内皮细胞之间的连接至关重要，这有助于稳定细胞连接。在蛋白质中间缺乏特定序列的Rasip 1突变形式不能与HEG 1结合，也不能定位于细胞连接处。这些研究为未来的工作打开了大门，以确定Rasip 1和HEG 1的相互作用是如何控制的，以及Rasip 1如何稳定血管。DOI：http://dx.doi.org/10.7554/eLife.11394.002网站
Heart of Glass (HEG1), a transmembrane receptor, and Rasip1, an endothelial-specific Rap1-binding protein, are both essential for cardiovascular development. Here we performed a proteomic screen for novel HEG1 interactors and report that HEG1 binds directly to Rasip1. Rasip1 localizes to forming endothelial cell (EC) cell-cell junctions and silencing HEG1 prevents this localization. Conversely, mitochondria-targeted HEG1 relocalizes Rasip1 to mitochondria in cells. The Rasip1-binding site in HEG1 contains a 9 residue sequence, deletion of which abrogates HEG1’s ability to recruit Rasip1. HEG1 binds to a central region of Rasip1 and deletion of this domain eliminates Rasip1’s ability to bind HEG1, to translocate to EC junctions, to inhibit ROCK activity, and to maintain EC junctional integrity. These studies establish that the binding of HEG1 to Rasip1 mediates Rap1-dependent recruitment of Rasip1 to and stabilization of EC cell-cell junctions. DOI: http://dx.doi.org/10.7554/eLife.11394.001 Blood vessels are lined with cells known as vascular endothelial cells. These cells are connected to each other at junctions that consist of several different proteins. The junctions help to control how the blood vessel develops and provide a barrier that controls the movement of water and certain other molecules through the vessel wall. This barrier becomes weakened in diseases like sepsis and atherosclerosis. Two proteins that are essential for the heart and blood vessels to develop correctly are called “Heart of Glass” (HEG1) and Rasip1. Although a protein has been identified that binds to HEG1 at the cell junctions, this binding only involves a small region of HEG1. This led de Kreuk, Gingras et al. to look for other proteins that interact with HEG1 and that might be important for controlling the development of the blood vessels. This revealed that HEG1 binds directly to Rasip1. Further experiments revealed that HEG1 is essential for targeting Rasip1 to the junctions between the endothelial cells, and that this helps to stabilize the cell junctions. Mutant forms of Rasip1 that lacked a particular sequence in the middle of the protein were unable to bind to HEG1 and did not localize to the cell junctions. These studies open the door to future work to define how the interaction of Rasip1 and HEG1 is controlled and how Rasip1 stabilizes blood vessels. DOI: http://dx.doi.org/10.7554/eLife.11394.002