Phorbol 12-myristate 13-acetate (TPA) blocks CD3-mediated Ca2+ mobilization in Jurkat T cells independently of protein kinase C activation.
Stimulation of Jurkat T cells with antibodies against the T cell receptor/CD3 complex induces a rise in the intracellular concentration of Ca2+ within seconds. The inositol phosphate-dependent Ca2+ mobilization induced by OKT3 was completely abrogated when Jurkat cells were pretreated for 1 min with the phorbol 12-myristate 13-acetate TPA (10nM), a concentration which activates protein kinase C (PKC). The effects of TPA on the Ca2+ fluxes were insensitive to treatment of the cells with known PKC inhibitors (H-7 and staurosporin) under conditions where the PKC-mediated phosphorylation was blocked. Furthermore, another activator of PKC, mezerein, inhibited the Ca2+ signal induced by OKT3. This inhibition, however, could completely be reversed by pretreatment with H-7 or staurosporine. We conclude that the TPA-mediated inhibition of Ca2+ fluxes in Jurkat T cells largely acts through a PKC-independent pathway.
Nordström
T
T
Department of Pathology, University of Helsinki, Finland.
Ståhls
A
A
Pessa-Morikawa
T
T
Mustelin
T
T
Andersson
L C
LC
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000276:immunology*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology*; D017252:CD3 Complex; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D016257:Fura-2; D006801:Humans; D007294:Inositol / Q000378:metabolism; D007295:Inositol Phosphates / Q000378:metabolism; D007546:Isoquinolines / Q000494:pharmacology; D010766:Phosphorylation; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D013050:Spectrometry, Fluorescence; D013601:T-Lymphocytes; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D007295:Inositol Phosphates; D007546:Isoquinolines; D010879:Piperazines; D011948:Receptors, Antigen, T-Cell; D007294:Inositol; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium; D016257:Fura-2