Gα12 interaction with αSNAP induces VE-cadherin localization at endothelial junctions and regulates barrier function

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Journal of Biological Chemistry


The involvement of heterotrimeric G proteins in the regulation of adherens junction function is unclear. We identified αSNAP as an interactive partner of Gα12 using yeast two-hybrid screening, glutathione S-transferase pull-down assays showed the selective interaction of αSNAP with Gα12 in COS-7 as well as in human umbilical vein endothelial cells. Using domain swapping experiments, we demonstrated that the N-terminal region of Gα12 (1-37 amino acids) was necessary and sufficient for its interaction with αSNAP. Ga13 with its N-terminal extension replaced by that of Gα12 acquired the ability to bind to aSNAP, whereas Gα12 with its N terminus replaced by that of Gα13 this ability. Using four point mutants of aSNAP, which alter its ability to bind to the SNARE complex, we determined that the convex rather than the concave surface of aSNAP was involved in its interaction with Ga12. Co-transfection of human umbilical vein endothelial cells with Gα12 and aSNAP stabilized VE-cadherin at the plasma membrane, whereas down-regulation of αSNAP with siRNA resulted in the loss of VE-cadherin from the cell surface and, when used in conjunction with Gα12 overexpression, decreased endothelial barrier function. Our results demonstrate a direct link between the α subunit of G 12 and αSNAP, an essential component of the membrane fusion machinery, and implicate a role for this interaction in regulating the membrane localization of VE-cadherin and endothelial barrier function. © 2005 by The American Society for Biochemistry and Molecular Biology, Inc.

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