The activation of calcium/phospholipid dependent protein kinase and the association with interleukin-2 production.
The thymic leukemia cell line EL4 has been shown to produce the lymphokine Interleukin-2 (IL-2) following stimulation with phorbol ester (PMA). We investigated intracellular enzyme pathways triggered by phorbol stimulation using an EL4 cell line which responds to PMA with IL-2 synthesis (EL4r) and one which does not produce IL-2 following stimulation (EL4nr). By comparing these two cell lines we hoped to establish which enzyme activities were associated with IL-2 synthesis. The enzyme pathways studied included calcium/phospholipid dependent protein kinase (C-kinase) activity, the induction of polyamine synthesis, RNA, DNA and protein synthesis and finally IL-2 production. Our results indicate that both EL4 cell lines have a receptor for PMA, which can activate the C-kinase enzyme. Further, in both cell lines PMA activates the nuclear synthesis of polyamines as demonstrated by ornithine decarboxylase induction. Both RNA and protein synthesis measured by 3H-uridine and 3H-leucine uptake respectively appear comparable between EL4r and EL4nr. The only difference in cellular responsiveness between EL4r and EL4nr was in the 3H-thymidine uptake, and IL-2 production. IL-2 production or lack of production was established by 3H-uridine and 3H-thymidine incorporation as well as viable cell count using the IL-2 dependent cell line CTLL-2. We, therefore, conclude that EL4r and EL4nr cells show similar intracellular responses to phorbol ester except for 3H-thymidine uptake and detectable IL-2 production. Our results suggest that failure of PMA-stimulated EL4nr cells to produce IL-2 is either due to inability of this cell line to synthesize IL-2 or the production of defective IL-2. It is not due to failure of PMA to activate C-kinase or the subsequent nuclear events.
D002118:Calcium / Q000494:pharmacology*; D002460:Cell Line; D002478:Cells, Cultured; D003470:Culture Media; D004247:DNA / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects*; D007376:Interleukin-2 / Q000096:biosynthesis*; D007942:Leukemia, Experimental / Q000378:metabolism; D009696:Nucleic Acids / Q000378:metabolism; D009955:Ornithine Decarboxylase / Q000378:metabolism; D010743:Phospholipids / Q000494:pharmacology*; D011493:Protein Kinase C / Q000502:physiology*; D012313:RNA / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D003470:Culture Media; D007376:Interleukin-2; D009696:Nucleic Acids; D010743:Phospholipids; D012313:RNA; D004247:DNA; D011493:Protein Kinase C; D009955:Ornithine Decarboxylase; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium