Altered expression of protein-tyrosine phosphatase 2C in 293 cells affects protein tyrosine phosphorylation and mitogen-activated protein kinase activation.
PTP2C, an SH2 domain-containing protein-tyrosine phosphatase, is recruited to the growth factor receptors upon stimulation of cells. To investigate its role in growth factor signaling, we have overexpressed by approximately 6-fold the native PTP2C and a catalytically inactive mutant of the enzyme in 293 human embryonic kidney cells. The native PTP2C was located entirely in the cytosol, while the inactive mutant was nearly equally distributed in cytsolic and membrane fractions. Expression of the latter caused hyperphosphorylation on tyrosine of a 43-kDa protein, which was coimmunoprecipitated and co-partitioned in the plasma membrane fraction with the inactive PTP2C mutant. This protein may represent a physiological substrate of PTP2C. Overexpression of the native PTP2C enhanced epidermal growth factor (EGF)-stimulated mitogen-activated protein (MAP) kinase activity by 30%, whereas expression of the inactive mutant reduced the stimulated activity by 50%. Similar effects were observed for the activation of MAP kinase as determined by activity assay, gel mobility shift, and tyrosine phosphorylation. The data suggest that the phosphatase activity of PTP2C is partly required for MAP kinase activation by EGF and that PTP2C may function by dephosphorylating the 43-kDa membrane protein.
Zhao
Z
Z
Department of Biochemistry, University of Washington, Seattle 98195, USA.
Tan
Z
Z
Wright
J H
JH
Diltz
C D
CD
Shen
S H
SH
Krebs
E G
EG
Fischer
E H
EH
D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D003600:Cytosol / Q000201:enzymology; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007668:Kidney; D008565:Membrane Proteins / Q000378:metabolism; D020929:Mitogen-Activated Protein Kinase Kinases; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000096:biosynthesis* / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D015398:Signal Transduction; D014162:Transfection
D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; C034241:ribophorin; D004815:Epidermal Growth Factor; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases; C516724:PTPN11 protein, human; C509249:PTPN6 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases