Tip cell-specific requirement for an atypical Gpr124- and Reck-dependent Wnt/β-catenin pathway during brain angiogenesis.
Tip cell-specific requirement for an atypical Gpr124- and Reck-dependent Wnt/β-catenin pathway during brain angiogenesis.
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DOI：
10.7554/elife.06489
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发表时间：
2015-06-08
期刊：
影响因子：
7.7
通讯作者：
Stainier DY
中科院分区：
文献类型：
--
作者：
Vanhollebeke B;Stone OA;Bostaille N;Cho C;Zhou Y;Maquet E;Gauquier A;Cabochette P;Fukuhara S;Mochizuki N;Nathans J;Stainier DY
尽管内皮Wnt/β-catenin信号在中枢神经系统（CNS）血管形成过程中起关键作用，但内皮细胞如何感知和响应特异性Wnt配体以及脑内血管形态发生的多步骤过程的哪些方面受这些血管生成信号控制仍然知之甚少。我们在斑马鱼胚胎的单细胞分辨率上解决了这些问题。我们确定GPI锚定MMP抑制剂Reck和粘附GPCR Gpr 124作为脑血管生成和背根神经节神经发生所需的Wnt 7a/Wnt 7 b特异性信号复合物的组成部分。我们进一步表明，这种非典型Wnt/β-catenin信号通路选择性地控制内皮尖端细胞功能，因此，在Wnt/β-catenin缺陷的神经周围血管中，单个野生型尖端细胞的镶嵌恢复足以启动CNS血管的形成。我们的研究结果确定了Wnt/β-catenin信号配体特异性的分子决定因素，并为通过紧密调节尖端细胞功能来控制血管侵袭的器官特异性提供了证据。DOI：http://dx.doi.org/10.7554/eLife.06489.001器官与为它们提供氧气和营养的血管网络一起发育。新血管生长的一种方式是从现有血管的侧面发芽，通过一个称为血管生成的过程。这一过程依赖于排列在血管内壁上的内皮细胞所接收的信号，这些信号引导细胞形成新的“芽”，由尖端细胞和柄细胞组成。在发育中的大脑中，Wnt/β-catenin信号通路有助于指导血管的形成。在这条通路中，一个名为Wnt的蛋白质家族成员向血管细胞表面的特定蛋白质发出信号。人们已经付出了很大的努力来揭示这些蛋白质的身份，许多研究着眼于小鼠胚胎大脑中的血管发育。在这项研究中，Vanhollebeke等人转向斑马鱼胚胎，以发现新的血管生成调节因子，并确定它们在大脑血管发育的多步骤过程中的作用。使用多种实验技术来改变和研究不同Wnt信号传导途径组分的活性。这些实验揭示了Wnt 7a和Wnt 7 b蛋白向含有蛋白Gpr 124和Reck的内皮细胞膜蛋白复合物发出信号。Vanhollebeke等人随后创建了“马赛克”斑马鱼胚胎，其中包含两种遗传上不同类型的细胞-缺少Wnt/β-catenin信号通路的一种成分的细胞和野生型细胞。对血管生长的可视化显示，所有发芽的新血管都具有正常的尖端细胞。然而，芽茎中的细胞可能是正常的，也可能缺少信号蛋白。这些发现表明，Wnt/β-catenin信号通过特异性作用于新芽尖端细胞的侵入行为来控制大脑中血管发育的模式，这是一种允许血管化的有效器官特异性控制的细胞机制。DOI：http://dx.doi.org/10.7554/eLife.06489.002网站
Despite the critical role of endothelial Wnt/β-catenin signaling during central nervous system (CNS) vascularization, how endothelial cells sense and respond to specific Wnt ligands and what aspects of the multistep process of intra-cerebral blood vessel morphogenesis are controlled by these angiogenic signals remain poorly understood. We addressed these questions at single-cell resolution in zebrafish embryos. We identify the GPI-anchored MMP inhibitor Reck and the adhesion GPCR Gpr124 as integral components of a Wnt7a/Wnt7b-specific signaling complex required for brain angiogenesis and dorsal root ganglia neurogenesis. We further show that this atypical Wnt/β-catenin signaling pathway selectively controls endothelial tip cell function and hence, that mosaic restoration of single wild-type tip cells in Wnt/β-catenin-deficient perineural vessels is sufficient to initiate the formation of CNS vessels. Our results identify molecular determinants of ligand specificity of Wnt/β-catenin signaling and provide evidence for organ-specific control of vascular invasion through tight modulation of tip cell function. DOI: http://dx.doi.org/10.7554/eLife.06489.001 Organs develop alongside the network of blood vessels that supply them with oxygen and nutrients. One way that new blood vessels grow is by sprouting out of the side of an existing vessel, via a process called angiogenesis. This process relies on signals that are received by the endothelial cells that line the inner wall of blood vessels, and that direct the cells to form a new ‘sprout’, consisting of tip and stalk cells. In the developing brain, the Wnt/β-catenin signaling pathway helps direct the formation of blood vessels. In this pathway, a member of a protein family called Wnt signals to specific proteins on the surface of the cells lining the blood vessels. Much effort has gone into uncovering the identity of these proteins, with many studies looking at blood vessel development in the brain of mouse embryos. In this study, Vanhollebeke et al. turned to zebrafish embryos to uncover new regulators of angiogenesis and define their roles during the multi-step process of blood vessel development in the brain. A variety of experimental techniques were used to alter and study the activity of different Wnt signaling pathway components. These experiments revealed that the Wnt7a and Wnt7b proteins signal to an endothelial cell membrane protein complex containing the proteins Gpr124 and Reck. Vanhollebeke et al. then created ‘mosaic’ zebrafish embryos, which contained two genetically distinct types of cells—cells that were missing one of the components of Wnt/β-catenin signaling pathway, and wild-type cells. Visualizing the growth of the vessels showed that all the new blood vessels that sprouted had normal tip cells. However, the cells in the stalk of the sprout could be either normal or missing a signaling protein. These findings demonstrate that Wnt/β-catenin signaling controls the pattern of blood vessel development in the brain by acting specifically on the invasive behaviors of the tip cells of new sprouts, a cellular mechanism that allows efficient organ-specific control of vascularization. DOI: http://dx.doi.org/10.7554/eLife.06489.002