title: Linkage of protein kinase C-beta activation and intracellular interleukin-2 accumulation in human naive CD4 T cells.
abstract: A critical role for protein kinase C (PKC) in signal transduction events has been well established. Moreover, studies of regulation in PKC levels suggest participation in mediating long-term cellular functions. Protein kinase C-beta (PKC-beta) has been reported to be involved in interleukin-2 (IL-2) synthesis in T lymphocytes. In this study, the role of PKC-beta in intracellular accumulation of IL-2 was investigated using specific inhibitors. Preincubation with two different PKC inhibitors, one specific for classical isotypes (alpha and beta I) Go6976, and one which inhibits both classical and non-classical isotypes, GF109203X, caused a complete block in cytoplasmic IL-2 accumulation when naive CD4 T cells were stimulated in the presence of CD2+CD28+phorbol myristate acetate (PMA). In contrast, preincubation with up to 1000 ng/ml of cyclosporin A (CsA) resulted in a reduction in the intracellular IL-2 detected, as observed by a decrease in the proportion of positive cells as well as a fall in the mean fluorescence intensity (MFI). CsA did not influence PKC-beta translocation. Flow cytometric assessments of PKC-beta and its isoforms beta I and beta II correlated with Western blotting analysis and these results were further supported by the use of PKC-beta-positive (HUT 78) and -negative (BW5147) T-cell lines. Using the specific inhibitors, Go6976 and GF109203X, the findings in this study suggest that activation and translocation of PKC-beta is critical for accumulation of intracellular IL-2. The influence of CsA in reducing but not blocking IL-2 synthesis is discussed. PMA-induced down-regulation of the CD4 antigen was observed in the presence of Go6976 and but not GF109203X, suggesting regulation by non-classical PKC isoforms.
authors.affiliation: Children's Research Centre, Our Lady's Hospital for Sick Children, Dublin, Ireland.
authors.forename: J
authors.initials: J
authors.lastname: Hassan
authors.forename: E
authors.initials: E
authors.lastname: Rainsford
authors.forename: D J
authors.initials: DJ
authors.lastname: Reen
mesh_terms: D015153:Blotting, Western; D015496:CD4-Positive T-Lymphocytes / Q000201:enzymology / Q000276:immunology*; D018929:Cell Culture Techniques; D003593:Cytoplasm / Q000201:enzymology; D005312:Fetal Blood / Q000276:immunology; D005434:Flow Cytometry; D006801:Humans; D007376:Interleukin-2 / Q000097:blood*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate
chemical_list: D007376:Interleukin-2; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate