The role of tyrosine phosphorylation of cortactin in the locomotion of endothelial cells.
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 Tyr482 significantly reduced Src-meditated tyrosine phosphorylation both in 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.
Huang
C
C
Department of Experimental Pathology, The Holland Laboratory, American Red Cross, Rockville, Maryland 20855, USA.
Liu
J
J
Haudenschild
C C
CC
Zhan
X
X
D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002465:Cell Movement / Q000502:physiology*; D051356:Cortactin; D004730:Endothelium, Vascular / Q000502:physiology; D000939:Epitopes / Q000276:immunology; D005455:Fluorescent Antibody Technique; D006801:Humans; D051379:Mice; D008840:Microfilament Proteins / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010748:Phosphopeptides / Q000737:chemistry; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism*; D017421:Sequence Analysis; D015398:Signal Transduction / Q000502:physiology; D018909:src Homology Domains; D019061:src-Family Kinases / Q000378:metabolism
D000199:Actins; C495868:CTTN protein, human; D051356:Cortactin; C495869:Cttn protein, mouse; D000939:Epitopes; D008840:Microfilament Proteins; D010748:Phosphopeptides; D019000:Phosphotyrosine; D019061:src-Family Kinases