Myristoylation of Protein Kinase C Beta II Peptide Inhibitor Facilitates Rapid Attenuation of Phorbol 12-myristate 13-acetate in Activated Superoxide Release in Isolated Rat Polymorphonuclear Leukocytes

Protein kinase C beta II (PKCβII) activates polymorphonuclear leukocyte (PMN) superoxide (SO) production via NADPH oxidase (NOX-2) phosphorylation to exacerbate myocardial ischemia/reperfusion (I/R) injury. In prior studies, myristoylation (myr) of PKCβII peptide inhibitor (N-myr-SLNPEWNET; myr- PKCβII-), which disrupts PKCβII translocation/phosphorylation of NOX-2, was shown to dosedependently attenuate PMN SO release induced by phorbol 12-myristate 13-acetate (PMA), a broadspectrum PKC agonist. However, the role of myr on the inhibitory effects of myr-PKCβII- has yet to be elucidated. We hypothesized that myr-PKCβII peptide activator (N-myr-SVEIWD; myr-PKCβII+) would augment, myr-PKCβII- would attenuate, and scrambled myr-PKCβII- (N-myr-WNPESLNTE; myr-PKCβIIscram), a control for myr, would not affect PMA-induced PMN SO release compared to unconjugated peptides and nontreated controls. Rat PMNs (5x10 ) were incubated for 15 min at 37 C in the presence/absence of SO dismutase (SOD; 10 μg/mL), unconjugated PKCβII+/-, myr-PKCβII+/-, or myr- PKCβII-scram (all 20 μM). SO release was measured by the change in absorbance at 550 nm via ferricytochrome c reduction after PMA (100 nM) stimulation for 390 sec. Data were analyzed by ANOVA using Student-Newman-Keuls post hoc analysis. Myr-PKCβII- significantly attenuated SO release (0.30±0.02; n=27; p