Although blood–brain barrier (BBB) compromise is central to the etiology of diverse central nervous system (CNS) disorders, endothelial receptor proteins that control BBB function are poorly defined. The endothelial G-protein-coupled receptor (GPCR) Gpr124 has been reported to be required for normal forebrain angiogenesis and BBB function in mouse embryos, but the role of this receptor in adult animals is unknown. Here Gpr124 conditional knockout (CKO) in the endothelia of adult mice did not affect homeostatic BBB integrity, but resulted in BBB disruption and microvascular hemorrhage in mouse models of both ischemic stroke and glioblastoma, accompanied by reduced cerebrovascular canonical Wnt–β-catenin signaling. Constitutive activation of Wnt–β-catenin signaling fully corrected the BBB disruption and hemorrhage defects of Gpr124-CKO mice, with rescue of the endothelial gene tight junction, pericyte coverage and extracellular-matrix deficits. We thus identify Gpr124 as an endothelial GPCR specifically required for endothelial Wnt signaling and BBB integrity under pathological conditions in adult mice. This finding implicates Gpr124 as a potential therapeutic target for human CNS disorders characterized by BBB disruption.
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We are grateful to members of the Kuo laboratory, J. Yang and P. Han for helpful comments. We thank P. Chu (Stanford Histology Core Facility), J. Perrino (Stanford Electron Microscopy Facility) and C. Crumpton, T. Knaak, B. Gomez, O. Herman and M. Bigos (Stanford Shared FACS Facility). FACS sorting and analysis used instruments in the Shared FACS Facility, obtained using NIH S10 Shared Instrument Grant (S10RR025518-01, S10RR027431-01) to the Stanford Shared FACS Facility. We thank M. Edwards (Department of Neurosurgery, Stanford University) for providing the human glioblastoma specimens. We thank R. Adams (Max Planck Institute for Molecular Biomedicine) for providing the Cdh5-CreER mice. We thank the National Cancer Institute–DCTD Repository for providing the GL261 cell line. J.C. was supported by an American Heart Association Postdoctoral Fellowship (15POST23020039) and M.R.M. was supported by the Stanford Medical Scientist Training Program (NIGMS GM07365). J.H.Z. was supported by a Howard Hughes Medical Institute Medical Research Fellows Program grant. H.Y.C. was supported by NIH grant P50-HG007735. This work was also supported by American Heart Association Innovative Science Award 12PILT12850014, a Stanford Stroke Collaborative Action Network Pilot Grant and NIH grants R01HL074267, R01NS064517, U01DK085527 and R01CA158528 to C.J.K.
The authors declare no competing financial interests.
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Low wnt/β-catenin signaling determines leaky vessels in the subfornical organ and affects water homeostasis in mice
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