12-Deoxyphorbol-13-O-phenylacetate-20-acetate is not protein kinase C-beta isozyme-selective in vivo.
The phorbol ester, 12-deoxyphorbol-13-O-phenylacetate-20-acetate (DOPPA) has been shown to activate specifically the protein kinase C (PKC)-beta 1 isozyme in vitro (1). We have investigated the potential of DOPPA as a PKC-beta 1/2 isozyme-specific agonist in intact cells, employing U937 cells, which express beta 1/2, epsilon and zeta PKC and in Swiss 3T3 cells which lack PKC-beta 1/2 but express alpha, delta, epsilon and zeta PKC. Immunoblot analysis with isozyme-specific antibodies indicated that DOPPA can mediate the subcellular redistribution and down-modulation of all endogenous PKC isozymes (except PKC-zeta) in both U937 and Swiss 3T3 cells. Prolonged treatment (> 6 h) of cultures in down-modulation studies is complicated by the metabolism of DOPPA to 12-deoxyphorbol-13-phenylacetate (DOPP), a compound which activates all PKC isozymes tested in vitro (Ryves, W. J., et al. (1991) FEBS Lett., 288, 5-9). Nevertheless, because DOPPA induced rapid and dose-dependent phosphorylation of p80 in cells which do not express PCK-beta, p80 phosphorylation in Swiss 3T3 cells indicates that DOPPA can activate a non-beta PKC in vivo. The data suggest that DOPPA cannot be used as a PKC-beta-selective agonist in intact cell studies.
Kiley
S C
SC
Protein Phosphorylation Laboratory, Imperial Cancer Research Fund, London, UK.
Olivier
A R
AR
Gordge
P C
PC
Ryves
W J
WJ
Evans
F J
FJ
Ways
D K
DK
Parker
P J
PJ
D016475:3T3 Cells; D000818:Animals; D004789:Enzyme Activation; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism*; D051379:Mice; D010703:Phorbol Esters / Q000378:metabolism / Q000494:pharmacology*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D014407:Tumor Cells, Cultured
D007527:Isoenzymes; D010703:Phorbol Esters; D011506:Proteins; C029705:12-deoxyphorbolphenylacetate-20-acetate; C029704:12-deoxyphorbolphenylacetate; D011493:Protein Kinase C