title: The Src-homology domain 2-bearing protein tyrosine phosphatase-1 inhibits antigen receptor-induced apoptosis of activated peripheral T cells.
abstract: Restimulation of Ag receptors on peripheral T lymphocytes induces tyrosine phosphorylation-based signaling cascades that evoke Fas ligand expression and induction of Fas-mediated programmed cell death. In view of the role for the Src homology domain 2-bearing protein tyrosine phosphatase-1 (SHP-1) in modulating TCR signaling, we investigated the influence of SHP-1 on TCR-mediated apoptosis by assaying the sensitivity of peripheral T cells from SHP-1-deficient viable motheaten (mev) mice to cell death following TCR restimulation. The results of these studies revealed mev peripheral T cells to be markedly more sensitive than wild-type cells to induction of cell death following TCR stimulation. By contrast, PMA/ionophore and anti-Fas Ab-induced apoptotic responses were no different in mev compared with wild-type activated cells. Enhanced apoptosis of TCR-restimulated mev lymphocytes was associated with marked increases in Fas ligand expression as compared with wild-type cells, but was almost abrogated in both mev and wild-type cells by Fas-Fc treatment. Thus, the increased sensitivity of mev T cells to apoptosis following TCR restimulation appears to reflect a TCR-driven phenomenon mediated through up-regulation of Fas-Fas ligand interaction and induction of the Fas signaling cascade. These findings, together with the hyperproliferative responses of mev peripheral T cells to initial TCR stimulation, indicate that SHP-1 modulation of TCR signaling translates to the inhibition of both T cell proliferation and activation and, as such, is likely to play a pivotal role in regulating the expansion of Ag-stimulated T cells during an immune response.
authors.affiliation: Department of Immunology, University of Toronto, The Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Ontario, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Zhang
authors.forename: A K
authors.initials: AK
authors.lastname: Somani
authors.forename: S
authors.initials: S
authors.lastname: Watt
authors.forename: G B
authors.initials: GB
authors.lastname: Mills
authors.forename: K A
authors.initials: KA
authors.lastname: Siminovitch
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000276:immunology*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D004789:Enzyme Activation / Q000235:genetics / Q000276:immunology; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D047908:Intracellular Signaling Peptides and Proteins; D008213:Lymphocyte Activation / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D054645:Protein Phosphatase 1; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D011948:Receptors, Antigen, T-Cell / Q000037:antagonists & inhibitors* / Q000502:physiology; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D015398:Signal Transduction / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology / Q000201:enzymology / Q000276:immunology*; D019014:fas Receptor / Q000096:biosynthesis / Q000502:physiology; D018909:src Homology Domains / Q000235:genetics / Q000502:physiology*
chemical_list: D007166:Immunosuppressive Agents; D047908:Intracellular Signaling Peptides and Proteins; D011948:Receptors, Antigen, T-Cell; D019014:fas Receptor; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D054645:Protein Phosphatase 1; 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