title: PTP-PEST targets a novel tyrosine site in p120 catenin to control epithelial cell motility and Rho GTPase activity.
abstract: Tyrosine phosphorylation is implicated in regulating the adherens junction protein, p120 catenin (p120), however, the mechanisms are not well defined. Here, we show, using substrate trapping, that p120 is a direct target of the protein tyrosine phosphatase, PTP-PEST, in epithelial cells. Stable shRNA knockdown of PTP-PEST in colon carcinoma cells results in an increased cytosolic pool of p120 concomitant with its enhanced tyrosine phosphorylation and decreased association with E-cadherin. Consistent with this, PTP-PEST knockdown cells exhibit increased motility, enhanced Rac1 and decreased RhoA activity on a collagen substrate. Furthermore, p120 localization is enhanced at actin-rich protrusions and lamellipodia and has an increased association with the guanine nucleotide exchange factor, VAV2, and cortactin. Exchange factor activity of VAV2 is enhanced by PTP-PEST knockdown whereas overexpression of a VAV2 C-terminal domain or DH domain mutant blocks cell motility. Analysis of point mutations identified tyrosine 335 in the N-terminal domain of p120 as the site of PTP-PEST dephosphorylation. A Y335F mutant of p120 failed to induce the 'p120 phenotype', interact with VAV2, stimulate cell motility or activate Rac1. Together, these data suggest that PTP-PEST affects epithelial cell motility by controlling the distribution and phosphorylation of p120 and its availability to control Rho GTPase activity.
authors.affiliation: Sealy Center for Cancer Biology and UTMB Comprehensive Cancer Center, University of Texas Medical Branch, Galveston, TX 77555, USA.
authors.forename: Rosario
authors.initials: R
authors.lastname: Espejo
authors.forename: Yowjiun
authors.initials: Y
authors.lastname: Jeng
authors.forename: Adriana
authors.initials: A
authors.lastname: Paulucci-Holthauzen
authors.forename: William
authors.initials: W
authors.lastname: Rengifo-Cam
authors.forename: Krysta
authors.initials: K
authors.lastname: Honkus
authors.forename: Panos Z
authors.initials: PZ
authors.lastname: Anastasiadis
authors.forename: Sarita K
authors.initials: SK
authors.lastname: Sastry
mesh_terms: D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics*; D003110:Colonic Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D004847:Epithelial Cells; D006801:Humans; D009154:Mutation; D010766:Phosphorylation / Q000235:genetics; D054594:Protein Tyrosine Phosphatase, Non-Receptor Type 12 / Q000235:genetics / Q000378:metabolism*; D014443:Tyrosine / Q000235:genetics; D020729:p120 GTPase Activating Protein / Q000235:genetics* / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D020729:p120 GTPase Activating Protein; D014443:Tyrosine; C516738:PTPN12 protein, human; D054594:Protein Tyrosine Phosphatase, Non-Receptor Type 12; D020741:rho GTP-Binding Proteins
keywords: Cell motility; PTP; Rho GTPase; p120 catenin