Regulation of Fibroblast Motility by the Protein Tyrosine Phosphatase PTP-PEST*
Abstract
The protein tyrosine phosphatase PTP-PEST is a cytosolic enzyme that displays a remarkable degree of selectivity for tyrosine-phosphorylated p130Cas as a substrate, bothin vitro and in intact cells. We have investigated the physiological role of PTP-PEST using Rat1 fibroblast-derived stable cell lines that we have engineered to overexpress PTP-PEST. These cell lines exhibit normal levels of tyrosine phosphorylation of the majority of proteins but have significantly lower levels of tyrosine phosphorylation of p130Cas than control cells. Initial cellular events occurring following integrin-mediated attachment to fibronectin (cell attachment and spreading) are essentially unchanged in cells overexpressing PTP-PEST; similarly, the extent and time course of mitogen-activated protein kinase activation in response to integrin engagement is unchanged. In contrast, the reduced phosphorylation state of p130Cas is associated with a considerably reduced rate of cell migration and a failure of cells overexpressing PTP-PEST to accomplish the normally observed redistribution of p130Casto the leading edge of migrating cells. Furthermore, cells overexpressing PTP-PEST demonstrate significantly reduced levels of association of p130Cas with the Crk adaptor protein. Our results suggest that one physiological role of PTP-PEST is to dephosphorylate p130Cas, thereby controlling tyrosine phosphorylation-dependent signaling events downstream of p130Cas and regulating cell migration.
Footnotes
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↵* This work was funded by Grant CA 53840 from the National Institutes of Health.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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↵‡ Current address: OSI Pharmaceuticals Inc., 106 Charles Lindbergh Blvd., Uniondale, NY 11553-3649.
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↵§ To whom correspondence should be addressed: Cold Spring Harbor Laboratory, 1 Bungtown Rd., Cold Spring Harbor, NY 11724-2208. Tel.: 516-367-8846; Fax: 516-367-6812; E-mail:tonks{at}cshl.org.
- Abbreviations:
- PTP
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protein tyrosine phosphatase
- PBS
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phosphate-buffered saline
- DMEM
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Dulbecco’s modified Eagle’s medium
- PAGE
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polyacrylamide gel electrophoresis
- MAP
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mitogen-activated protein.
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- Received October 5, 1998.
- Revision received November 17, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
