The role of protein kinase C isoenzymes in the regulation of calcineurin activity in human peripheral blood mononuclear cells.
It is known that PMA (phorbol-12-myristate-13-acetate) can activate the classical and novel protein kinase C isoenzymes (cPKC alpha, beta, gamma and nPKC delta, epsilon, eta, theta), while the calcium ion can induce only the activity of cPKC. Calcineurin binding protein (Cabin 1) belongs to the group of endogenous inhibitors of calcineurin. Cabin 1 becomes hyperphosphorylated in response to PKC activation and may play a negative role in calcineurin signalling. It was observed that both PMA treatment and the increase in intracellular Ca2+ contributed to the reduction of calcineurin activity in human peripheral blood mononuclear cells without modulating the mRNA and the protein levels of calcineurin. PMA and Ca-ionophore (A23187), the activating agents of PKC, applied alone or in combination, significantly increased the phosphorylation state of Cabin 1 as revealed by immunoprecipitation of Cabin 1 detecting its phospho-Ser content by specific antibodies. GF109203X, an inhibitor of the classic and the novel protein kinase C isoenzymes, and Gö6976, the selective inhibitor of the classical cPKC isoenzymes were able to abolish the effect of PMA or/and Ca-ionophore on the calcineurin activity with concomitant reversal of the hyperphosphorylation of Cabin 1. The calcineurin/Cabin 1 system was not influenced by Rottlerin, an inhibitor of PKC delta isoenzyme either in the absence or in the presence of Ca-ionophore and PMA. We presented evidence for the prominent role of cPKC alpha, beta, gamma isoenzymes in the inhibition of calcineurin as induced by PMA and Ca-ionophore. We demonstrated also that hyperphosphorylation of Cabin 1 by PMA/Ca2+-activated cPKC isoenzymes resulted in a simultaneous inhibition of calcineurin in peripheral blood mononuclear cells. These results suggest a negative regulatory role for Cabin 1 in calcineurin signalling and provide a possible mechanism of feedback inhibition through cross-talk between PKC and calcineurin.
Cell Biology and Signalling Research Group of the Hungarian Academy of Sciences, Department of Medical Chemistry, Research Centre for Molecular Medicine, University of Debrecen, H-4032 Debrecen, Hungary.
Zsolt
Z
Szíjgyártó
Kornélia
K
Szucs
Ildikó
I
Kovács
Róza
R
Zákány
Sándor
S
Sipka
Pál
P
Gergely
D048868:Adaptor Proteins, Signal Transducing; D001483:Base Sequence; D000001:Calcimycin / Q000494:pharmacology; D019703:Calcineurin / Q000097:blood* / Q000235:genetics; D065095:Calcineurin Inhibitors; D002227:Carbazoles / Q000494:pharmacology; D017931:DNA Primers / Q000235:genetics; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000097:blood; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism*; D008301:Maleimides / Q000494:pharmacology; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000097:blood*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D048868:Adaptor Proteins, Signal Transducing; C491861:CABIN1 protein, human; D065095:Calcineurin Inhibitors; D002227:Carbazoles; D017931:DNA Primers; D007211:Indoles; D007476:Ionophores; D007527:Isoenzymes; D008301:Maleimides; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; C081021:Go 6976; D000001:Calcimycin; D011493:Protein Kinase C; D019703:Calcineurin; C070515:bisindolylmaleimide I; D013755:Tetradecanoylphorbol Acetate