title: Functional proteomics identifies protein-tyrosine phosphatase 1B as a target of RhoA signaling.
abstract: Rho GTPases are signal transduction effectors that control cell motility, cell attachment, and cell shape by the control of actin polymerization and tyrosine phosphorylation. To identify cellular targets regulated by Rho GTPases, we screened global protein responses to Rac1, Cdc42, and RhoA activation by two-dimensional gel electrophoresis and mass spectrometry. A total of 22 targets were identified of which 19 had never been previously linked to Rho GTPase pathways, providing novel insight into pathway function. One novel target of RhoA was protein-tyrosine phosphatase 1B (PTP1B), which catalyzes dephosphorylation of key signaling molecules in response to activation of diverse pathways. Subsequent analysis demonstrated that RhoA enhances post-translational modification of PTP1B, inactivates phosphotyrosine phosphatase activity, and up-regulates tyrosine phosphorylation of p130Cas, a key mediator of focal adhesion turnover and cell migration. Thus, protein profiling reveals a novel role for PTP1B as a mediator of RhoA-dependent phosphorylation of p130Cas.
authors.affiliation: Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, USA.
authors.forename: Yukihito
authors.initials: Y
authors.lastname: Kabuyama
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Langer
authors.forename: Kirsi
authors.initials: K
authors.lastname: Polvinen
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Homma
authors.forename: Katheryn A
authors.initials: KA
authors.lastname: Resing
authors.forename: Natalie G
authors.initials: NG
authors.lastname: Ahn
mesh_terms: D045744:Cell Line, Tumor; D050719:Crk-Associated Substrate Protein / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D006801:Humans; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000502:physiology; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D040901:Proteomics; D015398:Signal Transduction / Q000502:physiology*; D015854:Up-Regulation / Q000502:physiology; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: C493841:BCAR1 protein, human; D050719:Crk-Associated Substrate Protein; D019000:Phosphotyrosine; C516607:PTPN1 protein, human; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein