The Role of Tyrosine Phosphorylation of Cortactin in the Locomotion of Endothelial Cells

doi:10.1074/jbc.273.40.25770

The Role of Tyrosine Phosphorylation of Cortactin in the Locomotion of Endothelial Cells*

From the ^‡Department of Experimental Pathology, The Holland Laboratory, American Red Cross, Rockville, Maryland 20855 and the Departments of ^¶Anatomy and Cell Biology and ^§Pathology, The George Washington University, Washington, D.C. 20037

Abstract

Cortactin, a filamentous actin cross-linking protein and a substrate of Src protein tyrosine kinase, is phosphorylated at tyrosine residues upon stimulation by extracellular signals. We have previously demonstrated that the filamentous actin cross-linking activity of cortactin is attenuated by Src (Huang, C., Ni, Y., Gao, Y., Haudenschild, C. C., and Zhan, X. (1997) J. Biol. Chem. 272, 13911–13915). In vitro, tyrosine phosphorylation of cortactin occurs specifically within the region between the proline-rich sequence and the Src homology 3 domain. Among the nine tyrosine residues in this region, mutations at Tyr⁴²¹, Tyr⁴⁶⁶, and Tyr⁴⁸²significantly reduced Src-meditated tyrosine phosphorylation bothin vitro and in vivo. Ectopic expression of wild-type cortactin in ECV304, a spontaneously transformed human umbilical endothelial cell line, resulted in an enhanced cell migration. In contrast, overexpression of a cortactin mutant deficient in tyrosine phosphorylation impaired the migration of endothelial cells. These findings reveal an intracellular signaling mechanism whereby the motility of endothelial cells is regulated by a Src-mediated tyrosine phosphorylation of cortactin.

Footnotes

↵* This study was supported by National Institutes of Health Grant R29 HL52753 (to X. Z.).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.
↵‖ To whom correspondence should be addressed: Dept. of Experimental Pathology, The Holland Laboratory, American Red Cross, 15601 Crabbs Branch Way, Rockville, MD 20855. Tel.: 301-738-0568; Fax: 301-738-0879; E-mail: zhanx{at}usa.redcross.org.
↵2 C. Huang, unpublished observations.
Abbreviations:

FGF

fibroblast growth factor

F-actin

filamentous actin

PAGE

polyacrylamide gel electrophoresis

PCR

polymerase chain reaction

SH3

Src homology 3

GST

glutathione S-transferase.
- Received June 1, 1998.
- Revision received July 27, 1998.
The American Society for Biochemistry and Molecular Biology, Inc.