VE-cadherin signaling induces EB3 phosphorylation to suppress microtubule growth and assemble adherens junctions.

Vascular endothelial (VE)-cadherin homophilic adhesion controls endothelial barrier permeability through assembly of adherens junctions (AJs). We observed that loss of VE-cadherin-mediated adhesion induced the activation of Src and phospholipase C (PLC)γ2, which mediated Ca(2+) release from endoplasmic reticulum (ER) stores, resulting in activation of calcineurin (CaN), a Ca(2+)-dependent phosphatase. Downregulation of CaN activity induced phosphorylation of serine 162 in end binding (EB) protein 3. This phospho-switch was required to destabilize the EB3 dimer, suppress microtubule (MT) growth, and assemble AJs. The phospho-defective S162A EB3 mutant, in contrast, induced MT growth in confluent endothelial monolayers and disassembled AJs. Thus, VE-cadherin outside-in signaling regulates cytosolic Ca(2+) homeostasis and EB3 phosphorylation, which are required for assembly of AJs. These results identify a pivotal function of VE-cadherin homophilic interaction in modulating endothelial barrier through the tuning of MT dynamics.

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