Activation of protein kinase C via the T-cell receptor complex potentiates cyclic AMP responses in T-cells

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Abstract
We have recently shown that activation of protein kinase C by tumour promoting phorbolesters, such as 4β-β-phorbol-12,13-dibutyrate, stimulates adenosine-induced accumulation of cAMP in 7urkat cells, a human T-leukaemia line. Activating the CD3 complex associated with the T-cell receptor by means of the monoclonal antibody OKT3 caused a concentration-dependent accumulation of inositol phosphates and an increase in the phosphorylation of an endogenous protein kinase C substrate. OKT3 also mimicked the previously reported effects of protein kinase C since it potentiated the cAMP stimulation by either an adenosine analogue, NECA, or cholera toxin. Thus, our results indicate that stimulation of a receptor activating phospholipase C and protein kinase C can secondarily enhance the action of agonists that act on adenylate cyclase-coupled receptors.