Characterization of phorbol esters activity on individual mammalian protein kinase C isoforms, using the yeast phenotypic assay.
An alternative in vivo assay, based on growth inhibition of yeast expressing an individual mammalian protein kinase C (PKC) isoform (proportional to the degree of PKC activation), was used to characterize the activities of phorbol-12-myristate-13-acetate (PMA) and its analogues on classical (alpha and betaI), novel (delta and eta) and atypical (zeta) PKC isoforms. Effects of PMA, 4alpha-PMA, phorbol-12-myristate-13-acetate-4-O-methyl-ether (MPMA), phorbol-12-monomyristate (PMM), phorbol-12,13-diacetate (PDA), phorbol-13-monoacetate (PA), phorbol-12,13-dibutyrate (PDB), phorbol-12,13-didecanoate (PDD) and 12-deoxyphorbol-13-phenylacetate-20-acetate (dPPA), on growth of yeast expressing individual PKC isoforms was determined. PMA-induced growth inhibition on all isoforms tested (except on PKC-zeta). PDD and PDB presented an efficacy similar to PMA; the other PMA-analogues presented lower efficacies. MPMA and 4alpha-PMA stimulated growth of yeast expressing classical PKCs and reduced the PMA-induced growth inhibition, effects similar to those exhibited by the PKC inhibitors chelerythrine and R-2,6-diamino-N-[[1-(1-oxotridecyl)-2-piperidinyl]methyl]-hexanamide dihydrochloride (NPC 15437). This study reveals that phorbol esters differ on their potency to activate a given PKC isoform, and presents their isoform-selectivity. Furthermore, MPMA and 4alpha-PMA caused effects similar to those expected from PKC inhibition.
Saraiva
Lucília
L
Serviço de Farmacologia, CEQOFFUP, Faculdade de Farmácia, Universidade do Porto, rua Aníbal Cunha, 164, 4050-047 Oporto, Portugal.
Fresco
Paula
P
Pinto
Eugénia
E
Gonçalves
Jorge
J
D000818:Animals; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D006131:Growth Inhibitors / Q000737:chemistry / Q000494:pharmacology; D007527:Isoenzymes / Q000378:metabolism; D051379:Mice; D010641:Phenotype; D010703:Phorbol Esters / Q000737:chemistry / Q000494:pharmacology*; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D015003:Yeasts / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics
D006131:Growth Inhibitors; D007527:Isoenzymes; D010703:Phorbol Esters; D011493:Protein Kinase C