Cho Chris, Smallwood Philip M, Nathans Jeremy
Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Neuron. 2017 Aug 30;95(5):1056-1073.e5. doi: 10.1016/j.neuron.2017.07.031. Epub 2017 Aug 10.
Reck, a GPI-anchored membrane protein, and Gpr124, an orphan GPCR, have been implicated in Wnt7a/Wnt7b signaling in the CNS vasculature. We show here that vascular endothelial cell (EC)-specific reduction in Reck impairs CNS angiogenesis and that EC-specific postnatal loss of Reck, combined with loss of Norrin, impairs blood-brain barrier (BBB) maintenance. The most N-terminal domain of Reck binds to the leucine-rich repeat (LRR) and immunoglobulin (Ig) domains of Gpr124, and weakening this interaction by targeted mutagenesis reduces Reck/Gpr124 stimulation of Wnt7a signaling in cell culture and impairs CNS angiogenesis. Finally, a soluble Gpr124(LRR-Ig) probe binds to cells expressing Frizzled, Wnt7a or Wnt7b, and Reck, and a soluble Reck(CC1-5) probe binds to cells expressing Frizzled, Wnt7a or Wnt7b, and Gpr124. These experiments indicate that Reck and Gpr124 are part of the cell surface protein complex that transduces Wnt7a- and Wnt7b-specific signals in mammalian CNS ECs to promote angiogenesis and regulate the BBB.
Reck是一种糖基磷脂酰肌醇（GPI）锚定膜蛋白，而Gpr124是一种孤儿G蛋白偶联受体（GPCR），它们参与中枢神经系统（CNS）脉管系统中的Wnt7a/Wnt7b信号传导。我们在此表明，血管内皮细胞（EC）中Reck的特异性减少会损害中枢神经系统血管生成，并且Reck在出生后的EC特异性缺失，与Norrin缺失相结合，会损害血脑屏障（BBB）的维持。Reck最N端结构域与Gpr124的富含亮氨酸重复序列（LRR）和免疫球蛋白（Ig）结构域结合，通过靶向诱变削弱这种相互作用会降低细胞培养中Reck/Gpr124对Wnt7a信号的刺激，并损害中枢神经系统血管生成。最后，可溶性Gpr124（LRR-Ig）探针与表达卷曲蛋白、Wnt7a或Wnt7b以及Reck的细胞结合，可溶性Reck（CC1-5）探针与表达卷曲蛋白、Wnt7a或Wnt7b以及Gpr124的细胞结合。这些实验表明，Reck和Gpr124是细胞表面蛋白复合物的一部分，该复合物在哺乳动物中枢神经系统ECs中转导Wnt7a和Wnt7b特异性信号以促进血管生成并调节血脑屏障。
