p120ctn Binds to the Membrane-proximal Region of the E-cadherin Cytoplasmic Domain and Is Involved in Modulation of Adhesion Activity*
- From the Department of Biochemistry, Faculty of Medicine, Kagoshima University, Kagoshima 890-8520, Japan
Abstract
Cadherins are transmembrane glycoproteins involved in Ca2+-dependent cell-cell adhesion. Previously, we showed that the conserved membrane-proximal region of the E-cadherin cytoplasmic domain negatively regulates adhesion activity. In this report, we provide several lines of evidence that p120ctn is involved in this negative regulation. p120ctn binds to the membrane-proximal region of the nonfunctional carboxyl-terminally deleted E-cadherin protein. An additional internal deletion in this region prevented the association with p120ctn and activated the protein, as seen in an aggregation assay. Furthermore, the nonfunctional E-cadherin can be activated through coexpression of p120ctn proteins with amino-terminal deletions, which eliminate several potential serine/threonine phosphorylation sites but do not affect the ability to bind to cadherins. Finally, we show that staurosporine, a kinase inhibitor, induces an increased electrophoretic mobility of p120ctn bound to E-cadherin polypeptides, activates the nonfunctional E-cadherin protein, and converts the wild-type E-cadherin and an E-cadherin-α-catenin chimeric protein from a cytochalasin D-sensitive to a cytochalasin D-insensitive state. Together, these results indicate that p120ctn is a modulator of E-cadherin-mediated cell adhesion.
Footnotes
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↵* This work was supported by grants from the Ministry of Education, Science, Sports and Culture of Japan and the Kodama Memorial Foundation.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵‡ To whom correspondence should be addressed. Tel.: 81-99-275-5246; Fax: 81-99-264-5618; E-mail: mozawa@med2.kufm.kagoshima-u. ac.jp.
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↵2 M. Ozawa, unpublished results.
- Abbreviations:
- PAGE
-
polyacrylamide gel electrophoresis
- CD
-
cytochalasin D
- EC0L
-
L cell expressing mutant E-cadherin lacking the cytoplasmic tail
- EΔC71L
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L cell expressing mutant E-cadherin with the carboxyl-terminal deletion of 71 amino acids
- EL
-
L cells expressing E-cadherin
- GST
-
glutathioneS-transferase
- HA
-
hemagglutinin
- mAb
-
monoclonal antibody
- PBS
-
phosphate-buffered saline
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- Received April 7, 1999.
- Revision received May 12, 1999.
- The American Society for Biochemistry and Molecular Biology, Inc.
