Positive effects of SH2 domain-containing tyrosine phosphatase SHP-1 on epidermal growth factor- and interferon-gamma-stimulated activation of STAT transcription factors in HeLa cells.
SHP-1 (also known as PTP1C, SHPTP-1, SHP, and HCP) is an SH2 domain-containing protein-tyrosine phosphatase. We have stably overexpressed the native form and a catalytically inactive cysteine to serine mutant of the enzyme, SHP-1-(Cys --> Ser), in human cervical carcinoma HeLa cells. Following stimulation of the cells with epidermal growth factor (EGF) and interferon-gamma (INF-gamma), signal transducers and activators of transcription (STAT) activity was analyzed by using two 32P-labeled DNA probes, namely hSIE which is derived from a high affinity mutant form of the serum-inducible element in the c-fos promotor and GAS which resembles the INF-gamma activation site. EGF induced hSIE binding activity only, and the activity was suppressed by approximately 70% when the inactive mutant form of SHP-1 was expressed but was essentially unaffected by expression of the native enzyme. INF-gamma treatment resulted in appearance of both hSIE and GAS binding activities. While expression of the inactive mutant reduced the activities by 30-50%, the native enzyme caused a 20-30% increase. Consistent with effects on STAT activation, altered SHP-1 expression also affected EGF-induced activation of the mitogen-activated protein kinase pathway; expression of SHP-1-(Cys --> Ser) inhibited activity of MEK by approximately 25%, whereas expression of SHP-1 resulted in a approximately 25% increase. Further studies revealed that overexpression of SHP-1 caused decreased tyrosine phosphorylation of the EGF receptor and that EGF induced phosphorylation and recruitment of SHP-1. Together, the data suggest that SHP-1 is positively involved in EGF- and INF-gamma-induced STAT activation in non-hematopoietic HeLa cells and that, in the EGF signaling system, SHP-1 functions at least partly by modulating tyrosine phosphorylation of EGF receptor.
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Division of Hematology, Department of Medicine, Department of Veterans Affairs Medical Center, Vanderbilt University, Nashville, Tennessee 37232-6305, USA.
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D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D066246:ErbB Receptors / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology*; D047908:Intracellular Signaling Peptides and Proteins; D048369:MAP Kinase Kinase 1; D020929:Mitogen-Activated Protein Kinase Kinases; D009154:Mutation; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism; D018909:src Homology Domains
D047908:Intracellular Signaling Peptides and Proteins; D014157:Transcription Factors; D014443:Tyrosine; D004815:Epidermal Growth Factor; D007371:Interferon-gamma; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D048369:MAP Kinase Kinase 1; C482125:MAP2K1 protein, human; 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