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G alpha12 interaction with alphaSNAP induces VE-cadherin localization at endothelial junctions and regulates barrier
Alexandra V Andreeva1, Mikhail A Kutuzov, Rita Vaiskunaite
1Department of Pharmacology, College of Medicine, University of Illinois, Chicago, Illinois 60612, USA.
The Journal of Biological Chemistry
|June 28, 2005
Summary
Researchers found that G alpha12 directly interacts with alphaSNAP, a protein involved in membrane fusion. This interaction is crucial for maintaining VE-cadherin at the cell surface and regulating endothelial barrier function.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- The role of heterotrimeric G proteins in regulating adherens junctions remains largely unknown.
- Adherens junctions are critical for maintaining tissue integrity and cell-cell adhesion.
Purpose of the Study:
- To investigate the interaction between G alpha12 and alphaSNAP.
- To elucidate the role of this interaction in endothelial barrier function and VE-cadherin localization.
Main Methods:
- Yeast two-hybrid screening to identify interacting partners.
- Glutathione S-transferase pull-down assays for interaction validation.
- Domain swapping and point mutagenesis experiments to map interaction sites.
- siRNA-mediated knockdown and overexpression studies in human umbilical vein endothelial cells.
Main Results:
- AlphaSNAP was identified as a specific binding partner of G alpha12.
- The N-terminal region of G alpha12 (amino acids 1-37) is essential for alphaSNAP binding.
- The convex surface of alphaSNAP mediates its interaction with G alpha12.
- G alpha12 and alphaSNAP co-localization stabilizes VE-cadherin at the plasma membrane.
- Down-regulation of alphaSNAP disrupts VE-cadherin localization and impairs endothelial barrier function.
Conclusions:
- A direct interaction exists between G alpha12 and alphaSNAP.
- This interaction is vital for regulating VE-cadherin membrane localization.
- The G alpha12-alphaSNAP complex plays a significant role in maintaining endothelial barrier integrity.