Single tyrosine mutation in VE-cadherin modulates gene lung expressions: evidence for FOXF1 mediated S1PR1 upregulation to stabilize vessels in mice

RationalePhosphorylation-dephosphorylation are processes involved in the adhesion of endothelial cells (ECs) to maintain vascular integrity in adults. VE-cadherin is a target for Src-mediated Y685 phosphorylation, identified in highly vascularized human glioblastoma where it is involved in the abnormal feature of tumor blood vessels. ObjectiveWe aimed at understanding the molecular mechanisms through which Y685F-VE-cadherin triggers S1PR1 gene expression and stabilizes lung vessels in adult mice. Methods and ResultsWe compared lung ECs from a knock-in (KI) mouse carrying a point mutation in VE-cadherin (Tyr 685 to Phe) to Wild type. Analysis of EC parameters showed a difference in the migratory rate was between ECs from KI (22.45% {+/-} 5.207) and WT (13.24% {+/-} 5.17) (p-value=0.034). The direct adhesion of ECs from KI mice to fibronectin was significantly higher (37.625 {+/-} 9.23) than that of the WT (26.8 {+/-} 3.258, p-value=0.012). In the fibrin bead assay, ECs from KI showed a weaker angiogenic response. The transcriptome of mutated ECs showed that 884 genes were dysregulated of which 766 genes were downregulated and 118 genes were upregulated. The Gene Ontology Enrichment showed that most of the genes were related to cell-cell adhesion and angiogenesis. Focusing on angiogenic genes, we found that Sphingosine-1-phosphate-receptor was a gene upregulated in mutated ECs which was confirmed by RT-PCR and westernblotting. Mechanistically, chromatin immunoprecipitation assay (CHIPS) demonstrated that FOXF1 directly bound to the S1pr1 promoter 7 fold greater than WT. As a consequence, VE-cadherin at the membrane was higher in the mutant vs WT (100 {+/-} 6.52 for WT vs 189.7 {+/-} 21.06 for KI (p-value 0.0001). Finally, lung morphometric analysis showed less vessels and vascular remodeling with no fibrosis in mutated mice. ConclusionsThese data extend our knowledge on pY-VE-cadherin mediated pathological angiogenesis and provide new therapeutic opportunities to vascular normalization through pharmacological inhibition of the Y685-VE-cadherin phosphorylation.