Differential effects of the protein kinase C activator phorbol 12-myristate 13-acetate on calcium responses and secretion in adherent and suspended RBL-2H3 mucosal mast cells.
Adhesion of RBL-2H3 mucosal mast cells to fibronectin-coated surfaces has been linked to changes in secretion and tyrosine kinase activity. We now show that adhesion affects the sensitivity of RBL cells to the protein kinase C activator phorbol 12-myristate 13-acetate (PMA). In suspended cells, PMA inhibited antigen-induced calcium influx (as measured by manganese influx) and changes in intracellular free calcium and had complex effects on antigen-stimulated secretion. However, in adherent cells PMA had little effect on these responses. Suspended cells only secreted in response to thapsigargin if they were co-treated with PMA, while adherent cells secreted in response to thapsigargin alone. The thapsigargin-induced secretion in adherent cells was inhibited by protein kinase C down-regulation and by the protein kinase C inhibitor GF 109203X, but not by calphostin C. We suggest that protein kinase C is constitutively activated in adherent cells, possibly due to modification of the regulatory domain of the enzyme.
Wolfe
P C
PC
Department of Pharmacology, Cornell University, Ithaca, New York 14853, USA.
Chang
E Y
EY
Rivera
J
J
Fewtrell
C
C
D000818:Animals; D000941:Antigens / Q000494:pharmacology; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D002448:Cell Adhesion; D004789:Enzyme Activation; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008407:Mast Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D013729:Terpenes / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D019284:Thapsigargin; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism
D000941:Antigens; D007527:Isoenzymes; D013729:Terpenes; D014443:Tyrosine; D019284:Thapsigargin; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium