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J Invest Dermatol. 2001 Nov;117(5):1059-67.

Tyrosine phosphorylation of human keratinocyte beta-catenin and plakoglobin reversibly regulates their binding to E-cadherin and alpha-catenin.

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1
Department of Dermatology, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina 27599-7287, USA.

Abstract

We show that tyrosine phosphorylation, produced by incubation of normal human keratinocytes with the tyrosine phosphatase inhibitor peroxovanadate, directly and reversibly regulates the association of beta-catenin and plakoglobin with E-cadherin and alpha-catenin. Prior studies have demonstrated a correlative, but not causal, association between increased tyrosine phosphorylation and decreased adherens junction mediated cell-cell adhesion. We observed that (i) binding of tyrosine phosphorylated beta-catenin and plakoglobin to E-cadherin and to alpha-catenin was substantially reduced, but could be restored in vitro by removal of phosphate from beta-catenin and plakoglobin with added tyrosine phosphatase, and (ii) tyrosine phosphorylation of beta-catenin and plakoglobin was associated with decreased cell-cell adhesion. These findings support a direct and causal role for tyrosine phosphorylation of beta-catenin and plakoglobin in regulating adherens junction mediated cell-cell adhesion. We propose that tyrosine phosphorylation of specific and probably different residues is responsible for regulating the binding of beta-catenin or plakoglobin to (i) E-cadherin and (ii) alpha-catenin. Additionally, because beta-catenin and plakoglobin have both structural and regulatory functions, the data raise the possibility that beta-catenin or plakoglobin released from the adherens junctions by tyrosine phosphorylation may transduce a signal to the nucleus regarding the adhesive state of the cell.

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