title: Interleukin 2- and polyomavirus middle T antigen-induced modification of phosphatidylinositol 3-kinase activity in activated T lymphocytes.
abstract: Stimulation of activated T lymphocytes with interleukin 2 (IL-2) results in rapid increases in intracellular protein tyrosine phosphorylation. Both the identity of the protein tyrosine kinase (PTK) activated by IL-2 receptor ligation and the identities of the critical target proteins for this PTK remain largely undefined. In this article, we demonstrate that stimulation of activated murine or human T cells with IL-2 for 10 to 30 min induces two- to threefold increases in the level of phosphatidylinositol (PtdIns) 3-kinase activity present in antiphosphotyrosine (p-Tyr) antibody immunoprecipitates from these cells. Furthermore, substantial levels of PtdIns 3-kinase activity were coprecipitated from IL-2-deprived T cells by antibodies to the src-related PTK p59fyn. Cellular stimulation with IL-2 induced a two- to threefold increase in the level of p59fyn-associated PtdIns 3-kinase activity. To examine the effect of a constitutive increase in PtdIns 3-kinase activity on the growth factor responsiveness of activated T cells, murine CTLL-2 cells were transfected with a polyomavirus middle T antigen (MTAg) expression vector. Anti-p-Tyr and anti-p59fyn immunoprecipitates from MTAg-transfected CTLL-2 cells contained three- to sixfold higher levels of PtdIns 3-kinase activity than wild-type cells. Immune complex kinase assays revealed that MTAg expression concomitantly induced a constitutive threefold increase in the PTK activity of p59fyn in these cells. However, stable MTAg expression did not abrogate the dependence of CTLL-2 cells on exogenous IL-2 for continued growth and proliferation.
authors.affiliation: Department of Immunology, Mayo Clinic/Foundation, Rochester, Minnesota 55905.
authors.forename: J A
authors.initials: JA
authors.lastname: Augustine
authors.forename: S L
authors.initials: SL
authors.lastname: Sutor
authors.forename: R T
authors.initials: RT
authors.lastname: Abraham
mesh_terms: D019870:1-Phosphatidylinositol 4-Kinase; D000818:Animals; D000936:Antigen-Antibody Complex; D000952:Antigens, Polyomavirus Transforming / Q000494:pharmacology*; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism / Q000494:pharmacology*; D008213:Lymphocyte Activation; D051379:Mice; D010770:Phosphotransferases / Q000378:metabolism*; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases / Q000276:immunology / Q000378:metabolism; D013601:T-Lymphocytes / Q000201:enzymology* / Q000276:immunology
chemical_list: D000936:Antigen-Antibody Complex; D000952:Antigens, Polyomavirus Transforming; D007376:Interleukin-2; D010770:Phosphotransferases; D019870:1-Phosphatidylinositol 4-Kinase; D011505:Protein-Tyrosine Kinases