GPR126 is a specifier of blood-brain barrier formation in the mouse central nervous system
Nikolaos Kakogiannos, … , Donato Inverso, Monica Giannotta
Nikolaos Kakogiannos, … , Donato Inverso, Monica Giannotta
Published August 1, 2024
Citation Information: J Clin Invest. 2024;134(15):e165368. https://doi.org/10.1172/JCI165368.
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Research Article Angiogenesis Vascular biology

GPR126 is a specifier of blood-brain barrier formation in the mouse central nervous system

Abstract

The blood-brain barrier (BBB) acquires unique properties to regulate neuronal function during development. The formation of the BBB, which occurs in tandem with angiogenesis, is directed by the Wnt/β-catenin signaling pathway. Yet the exact molecular interplay remains elusive. Our study reveals the G protein–coupled receptor GPR126 as a critical target of canonical Wnt signaling, essential for the development of the BBB’s distinctive vascular characteristics and its functional integrity. Endothelial cell–specific deletion of the Gpr126 gene in mice induced aberrant vascular morphogenesis, resulting in disrupted BBB organization. Simultaneously, heightened transcytosis in vitro compromised barrier integrity, resulting in enhanced vascular permeability. Mechanistically, GPR126 enhanced endothelial cell migration, pivotal for angiogenesis, acting through an interaction between LRP1 and β1 integrin, thereby balancing the levels of β1 integrin activation and recycling. Overall, we identified GPR126 as a specifier of an organotypic vascular structure, which sustained angiogenesis and guaranteed the acquisition of the BBB properties during development.

Authors

Nikolaos Kakogiannos, Anna Agata Scalise, Emanuele Martini, Claudio Maderna, Andrea Francesco Benvenuto, Michele D’Antonio, Laura Carmignani, Serena Magni, Giorgia Serena Gullotta, Maria Grazia Lampugnani, Fabio Iannelli, Galina V. Beznoussenko, Alexander A. Mironov, Camilla Cerutti, Katie Bentley, Andrew Philippides, Federica Zanardi, Marco Bacigaluppi, Sara Sigismund, Claudia Bassani, Cinthia Farina, Gianvito Martino, Marco De Giovanni, Elisabetta Dejana, Matteo Iannacone, Donato Inverso, Monica Giannotta

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Figure 3

GPR126 orchestrates BM protein deposition and ensures vascular pericyte coverage.

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GPR126 orchestrates BM protein deposition and ensures vascular pericyte ...
(A) Tomography slices of brain capillary longitudinal sections from WT and Gpr126iECKO mice at P18. White arrows, regular BM thickness; red arrows, interrupted or thin BM. See Supplemental Figure 5A for full image. Scale bars: 350 nm. (B) Confocal images of brain cortex cryosections from WT and Gpr126iECKO mice at P18. Vessels stained with podocalyxin or PECAM-1 (green), and BM with fibronectin or collagen IV (red). Arrowheads, protein colocalization and discontinuous collagen IV staining. See Supplemental Figure 5B for full image. Scale bars: 100 μm. (C and D) Quantification of fibronectin and collagen IV coverage in podocalyxin-positive and PECAM-1–positive areas, shown in B (n = 4 WT, n = 3–4 Gpr126iECKO mice). (E) Confocal images of brain cortex cryosections from WT and Gpr126iECKO mice at P18 show PECAM-1 (green, ECs) and PDGFR-β (red, pericytes). Arrowheads, discontinuous or absent PDGFR-β staining. Scale bar: 200 μm. (F) Quantification of PDGFR-β coverage in PECAM-1–positive areas, shown in E (n = 5 WT, n = 5 Gpr126iECKO mice). (G) Real-time qPCR of tek and Pdgfrb expression in fBECs (n = 4 WT, n = 5 Gpr126iECKO mice). (H) Confocal images of PECAM-1 (green, ECs), CD13 (red, pericytes), and collagen IV (magenta, BM) in WT and Gpr126iECKO retinas at P18. See Supplemental Figure 6A for the same field with different staining. Scale bars: 500 μm. Magnified insets show pericyte bodies, CD13 staining, and collagen IV structures without PECAM-1. Scale bars: 50 μm. (I) Quantification of CD13 coverage in PECAM-1–positive areas from images in H (n = 5 WT, n = 6 Gpr126iECKO retinas). (J) Quantification of collagen IV coverage in PECAM-1–positive areas, shown in H (n = 5 WT, n = 4 Gpr126iECKO mice). Data are shown as means ± SD, unpaired t tests with Welch’s correction. *P <0.05; **P <0.01; ***P <0.001.