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The Role of VE‐PTP Scaffold in Stabilizing the Adherens Junction
Author(s) -
Juettner Vanessa,
Dan Arkaprava,
Leckband Deborah,
Komarova Yulia,
Malik Asrar
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.1065.2
Subject(s) - adherens junction , cadherin , microbiology and biotechnology , ve cadherin , protein tyrosine phosphatase , phosphatase , chemistry , rac1 , biology , phosphorylation , biochemistry , signal transduction , cell
The Vascular Endothelial Protein Tyrosine Phosphatase (VE‐PTP) is an endothelial‐specific phosphatase that dephosphorylates multiple proteins including Vascular Endothelial (VE)‐cadherin, the main adhesion protein of adherens junctions (AJ). However, the role of VE‐PTP in stabilization of VE‐cadherin adhesion complexes remains unclear. VE‐cadherin establishes adhesion events through trans interactions with opposing VE‐cadherin molecules at AJs. In resting endothelial monolayers, it undergoes continues exchange between junctional and cytosolic pools. Using VE‐cadherin tagged with the photoconvertable protein Dendra2, we have demonstrated that VE‐PTP regulates steady‐state kinetics of VE‐cadherin at AJs in a phosphatase‐independent manner. Overexpression of wild‐type (WT) or phosphatase “dead” VE‐PTP mutant similarly decreased the VE‐cadherin dissociation rate from AJs as compared to control cells expressing empty vector. In agreement with these results, VE‐PTP depletion increased VE‐cadherin dissociation rate from AJs. Furthermore, treatment of the cells with the VE‐PTP phosphatase inhibitor, AKB‐9785, did not alter VE‐cadherin dynamics suggesting that VE‐PTP promoted stability of VE‐cadherin adhesion by decreasing VE‐cadherin dissociation rate in a phosphatase‐independent manner. Because Rac1 stabilizes AJs by reducing mechanical tension across VE‐cadherin adhesion, we analyzed junctional activity of Rac1 as well as the tension applied to VE‐cadherin using respective FRET biosensors. We observed that overexpression of VE‐PTP caused both Rac1 activation at AJs and reduction of tension across VE‐cadherin adhesion. Consistent with these results, VE‐PTP knockdown decreased Rac1 activity at AJs and increased stress at AJs determined using micropillar arrays. Cumulatively, our data suggest a scaffold role of VE‐PTP in regulating Rac1 activity at AJs. Future studies will further investigate the molecular mechanisms by which VE‐PTP activates Rac1. Support or Funding Information Funding: National Institutes of Health grant R01 HL103922 to Y.A. Komarova, and T32 and RO1 HL45638 to A.B. Malik.