title: Hematopoietic protein tyrosine phosphatase suppresses extracellular stimulus-regulated kinase activation.
abstract: The mitogen-activated protein kinases (MAPKs) are signaling molecules that become enzymatically activated through phosphorylation by diverse stimuli. Hematopoietic cytokines, growth factors, and stimulated lymphocyte antigen receptors may activate specific MAPKs by altering the balance of MAPK-activating protein kinases and the protein phosphatases that target their activation sites. Hematopoietic protein tyrosine phosphatase (HePTP) is a hematopoiesis-specific cytoplasmic protein tyrosine phosphatase whose expression is induced by mitogenic stimuli. To investigate the role of HePTP in hematopoietic development, we constructed mice deficient in this phosphatase using the technique of homologous recombination. Primary lymphocytes from HePTP(-/-) mice show enhanced activation of extracellular stimulus-regulated kinase (ERK) after both phorbol myristate acetate (PMA) and anti-CD3-mediated T-cell receptor (TCR) stimulation, suggesting a true physiological relationship between these two molecules. Activation of MEK, the physiological activator of ERK, by anti-CD3 or PMA is not affected by HePTP deletion. The distribution of hematopoietic lineages in bone marrow and peripheral blood samples and the in vitro proliferative capacity of bone marrow progenitors from HePTP deletion mice do not deviate from those of matched littermate controls. Similarly, lymphocyte activation and development are indistinguishable in HePTP(-/-) mice and controls. We conclude that HePTP is a physiological regulator of ERK on the basis of these studies and hypothesize that its deletion is well compensated for in the developing mouse through reduction of ERK targets or enhancement of physiologically opposed signaling pathways.
authors.affiliation: Department of Medical Biophysics, University of Toronto, Princess Margaret Hospital and Ontario Cancer Institute, Toronto, Ontario M5G 2M9, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Gronda
authors.forename: S
authors.initials: S
authors.lastname: Arab
authors.forename: B
authors.initials: B
authors.lastname: Iafrate
authors.forename: H
authors.initials: H
authors.lastname: Suzuki
authors.forename: B W
authors.initials: BW
authors.lastname: Zanke
mesh_terms: D000818:Animals; D001665:Binding Sites; D017252:CD3 Complex / Q000378:metabolism; D002455:Cell Division; D019070:Cell Lineage; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D017353:Gene Deletion; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D008957:Models, Genetic; D010766:Phosphorylation; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism* / Q000502:physiology*; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D011995:Recombination, Genetic; D018417:Th1 Cells / Q000378:metabolism; D018418:Th2 Cells / Q000378:metabolism; D013997:Time Factors
chemical_list: D017252:CD3 Complex; D047908:Intracellular Signaling Peptides and Proteins; D011948:Receptors, Antigen, T-Cell; D020928:Mitogen-Activated Protein Kinases; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; C509248:Ptpn6 protein, mouse