PTP-PEST controls motility through regulation of Rac1.
The cytoplasmic protein tyrosine phosphatase, PTP-PEST, associates with the focal adhesion proteins p130cas and paxillin and has recently been implicated in cell migration. In this study, we investigated the mechanism by which PTP-PEST regulates this phenomenon. We find that PTP-PEST is activated in an adhesion-dependent manner and localizes to the tips of membrane protrusions in spreading fibroblasts. We show that the catalytic activity of PTP-PEST is a key determinant for its effects on motility. Overexpression of PTP-PEST, but not a catalytically inactive form, impairs haptotaxis, cell spreading and formation of membrane protrusions in CHOK1 cells. In addition, overexpression of PTP-PEST in Rat1 fibroblasts perturbs membrane ruffling and motility in response to PDGF stimulation. The expression level of PTP-PEST modulates the activity of the small GTPase, Rac1. PTP-PEST overexpression suppresses activation of Rac1 in response to both integrin-mediated adhesion or growth factor stimulation. In contrast, fibroblasts that lack PTP-PEST expression show enhanced Rac1 activity. Co-expression of constitutively active Rac1 with PTP-PEST overcomes the inhibition of cell spreading and migration indicating that PTP-PEST acts by antagonizing Rac1 activation. Our data suggest a model in which PTP-PEST is activated by integrins and localized to regions where it can control motile events at the leading edge through inhibition of the small GTPase Rac1.
Sastry
Sarita K
SK
Department of Cell and Developmental Biology and Lineberger Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA. sksastry@med.unc.edu
Lyons
Patrick D
PD
Schaller
Michael D
MD
Burridge
Keith
K
D000818:Animals; D016466:CHO Cells; D020134:Catalytic Domain / Q000502:physiology; D002448:Cell Adhesion / Q000235:genetics*; D002465:Cell Movement / Q000235:genetics*; D022081:Cell Surface Extensions / Q000201:enzymology* / Q000648:ultrastructure; D006224:Cricetinae; D005057:Eukaryotic Cells / Q000166:cytology / Q000201:enzymology*; D005109:Extracellular Matrix / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology / Q000201:enzymology; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology; D016023:Integrins / Q000378:metabolism; D008954:Models, Biological; D054594:Protein Tyrosine Phosphatase, Non-Receptor Type 12; D017027:Protein Tyrosine Phosphatases / Q000172:deficiency* / Q000235:genetics; D051381:Rats; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D020830:rac1 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
D016023:Integrins; D020794:Receptor Protein-Tyrosine Kinases; D054594:Protein Tyrosine Phosphatase, Non-Receptor Type 12; D017027:Protein Tyrosine Phosphatases; C516740:Ptpn12 protein, rat; D020830:rac1 GTP-Binding Protein