TY - JOUR
T1 - Dlg1 activates beta-catenin signaling to regulate retinal angiogenesis and the blood-retina and blood-brain barriers
AU - Cho, Chris
AU - Wang, Yanshu
AU - Smallwood, Philip M.
AU - Williams, John
AU - Nathans, Jeremy
N1 - Funding Information:
In the present study, we have identified a role for endothelial Dlg1 in retinal angiogenesis and BBB/BRB development as determined by the phenotype of mice with EC-specific knockout of Dlg1. We provide evidence for a genetic interaction between Dlg1 and Fz4, Tspan12, and Ndp (the gene coding for Norrin), which suggests that Dlg1 stimulates beta-catenin signaling in CNS ECs. This idea is supported by the finding that Dlg1 enhances beta-catenin signaling in cultured cells and by rescue of the Dlg1 EC-specific knockout phenotype upon constitutive beta-catenin stabilization in vivo. Intriguingly, although the first two PDZ domains of Dlg1 bind in vitro to a consensus PDZ-binding motif at the Fz4 C-terminus, genetic epistasis analyses of the EC-specific Dlg1 knockout and a CRISPR/Cas9-generated mutation of the Fz4 PDZ-binding motif argues that these two proteins function independently in the context of beta-catenin signaling.
Publisher Copyright:
© Cho et al.
PY - 2019/5
Y1 - 2019/5
N2 - Beta-catenin (i.e., canonical Wnt) signaling controls CNS angiogenesis and the blood- brain and blood-retina barriers. To explore the role of the Discs large/membrane-associated guanylate kinase (Dlg/MAGUK) family of scaffolding proteins in beta-catenin signaling, we studied vascular endothelial cell (EC)-specific knockout of Dlg1/SAP97. EC-specific loss of Dlg1 produces a retinal vascular phenotype that closely matches the phenotype associated with reduced beta- catenin signaling, synergizes with genetically-directed reductions in beta-catenin signaling components, and can be rescued by stabilizing beta-catenin in ECs. In reporter cells with CRISPR/ Cas9-mediated inactivation of Dlg1, transfection of Dlg1 enhances beta-catenin signaling ~4 fold. Surprisingly, Frizzled4, which contains a C-terminal PDZ-binding motif that can bind to Dlg1 PDZ domains, appears to function independently of Dlg1 in vivo. These data expand the repertoire of Dlg/MAGUK family functions to include a role in beta-catenin signaling, and they suggest that proteins other than Frizzled receptors interact with Dlg1 to enhance beta-catenin signaling.
AB - Beta-catenin (i.e., canonical Wnt) signaling controls CNS angiogenesis and the blood- brain and blood-retina barriers. To explore the role of the Discs large/membrane-associated guanylate kinase (Dlg/MAGUK) family of scaffolding proteins in beta-catenin signaling, we studied vascular endothelial cell (EC)-specific knockout of Dlg1/SAP97. EC-specific loss of Dlg1 produces a retinal vascular phenotype that closely matches the phenotype associated with reduced beta- catenin signaling, synergizes with genetically-directed reductions in beta-catenin signaling components, and can be rescued by stabilizing beta-catenin in ECs. In reporter cells with CRISPR/ Cas9-mediated inactivation of Dlg1, transfection of Dlg1 enhances beta-catenin signaling ~4 fold. Surprisingly, Frizzled4, which contains a C-terminal PDZ-binding motif that can bind to Dlg1 PDZ domains, appears to function independently of Dlg1 in vivo. These data expand the repertoire of Dlg/MAGUK family functions to include a role in beta-catenin signaling, and they suggest that proteins other than Frizzled receptors interact with Dlg1 to enhance beta-catenin signaling.
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U2 - 10.7554/eLife.45542
DO - 10.7554/eLife.45542
M3 - Article
C2 - 31066677
AN - SCOPUS:85065792418
SN - 2050-084X
VL - 8
JO - eLife
JF - eLife
M1 - e45542
ER -