SHP-1 phosphatase C-terminus interacts with novel substrates p32/p30 during erythropoietin and interleukin-3 mitogenic responses.
SHP-1 protein tyrosine phosphatase is a critical negative regulator of mitogenic signaling, as demonstrated by the heightened growth responses to hematopoietic growth factors in hematopoietic cells of motheaten mice, which lack functional SHP-1 expression due to mutations in the SHP-1 gene. The mitogenic signaling molecules dephosphorylated by SHP-1 have not been fully identified. We detected two proteins (p32/p30) that are hyperphosphorylated in a DA3/erythropoietin receptor (EpoR) cell line that expresses a mutant containing the SHP-1 C-terminus that suppresses the function of the endogenous phosphatase and induces hyperproliferative responses to interleukin-3 (IL-3) and Epo. Hyperphosphorylated p32/p30 are also detected in motheaten hematopoietic cells, demonstrating an association of p32/p30 hyperphosphorylation with SHP-1-deficiency and growth factor-hyperresponsiveness. The hyperphosphorylated p32/30 associate with SHP-1 via its C-terminus, because they coimmunoprecipitate with the phosphatase and the C-terminal mutant and they bind in vitro to a synthetic peptide of the mutant but not the GST fusion proteins of SHP-1 SH2 domains. Induction of p32/p30 phosphorylation by IL-3 or Epo occurs mainly at 2 to 18 hours poststimulation in the DA3/EpoR cell line, indicating p32/p30 as novel signaling molecules during cell cycle progression. These data demonstrate a function for the SHP-1 C-terminus in recruiting potential substrates p32/p30 and suggest that SHP-1 may regulates mitogenic signaling by dephosphorylating p32/p30.
Yang
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W
Department of Cancer Biology, The Lerner Research Institute of the Cleveland Clinic Foundation, Cleveland, OH, USA.
Tabrizi
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M
Berrada
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Yi
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D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001854:Bone Marrow Cells / Q000187:drug effects / Q000378:metabolism; D002460:Cell Line; D004921:Erythropoietin / Q000494:pharmacology*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006412:Hematopoietic Stem Cells / Q000187:drug effects / Q000378:metabolism; D007377:Interleukin-3 / Q000494:pharmacology*; D047908:Intracellular Signaling Peptides and Proteins; D053614:Janus Kinase 2; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D008817:Mice, Mutant Strains; D008934:Mitogens / Q000494:pharmacology*; D008938:Mitosis / Q000187:drug effects* / Q000502:physiology; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; 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 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D017467:Receptors, Erythropoietin / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D015398:Signal Transduction / Q000502:physiology*; D013154:Spleen / Q000166:cytology; D013379:Substrate Specificity; D014162:Transfection; D018631:ras Proteins / Q000378:metabolism; D018909:src Homology Domains
D007377:Interleukin-3; D047908:Intracellular Signaling Peptides and Proteins; D008934:Mitogens; D010446:Peptide Fragments; D011506:Proteins; D011518:Proto-Oncogene Proteins; D017467:Receptors, Erythropoietin; D011993:Recombinant Fusion Proteins; D004921:Erythropoietin; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D011505:Protein-Tyrosine Kinases; C507926:Jak2 protein, mouse; D053614:Janus Kinase 2; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; C516725:Ptpn11 protein, mouse; C509248:Ptpn6 protein, mouse; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D018631:ras Proteins