title: Attenuation of the hypoxia-induced protein kinase Cdelta interaction with the 'd' subunit of F1Fo-ATP synthase in neonatal cardiac myocytes: implications for energy preservation and survival.
abstract: The F1Fo-ATP synthase provides most of the heart's energy, yet events that alter its function during injury are poorly understood. Recently, we described a potent inhibitory effect on F1Fo-ATP synthase function mediated by the interaction of PKCdelta (protein kinase Cdelta) with dF1Fo ('d' subunit of the F1Fo-ATPase/ATP synthase). We have now developed novel peptide modulators which facilitate or inhibit the PKCdelta-dF1Fo interaction. These peptides include HIV-Tat (transactivator of transcription) protein transduction and mammalian mitochondrial-targeting sequences. Pre-incubation of NCMs (neonatal cardiac myocyte) with 10 nM extracellular concentrations of the mitochondrial-targeted PKCdelta-dF1Fo interaction inhibitor decreased Hx (hypoxia)-induced co-IP (co-immunoprecipitation) of PKCdelta with dF1Fo by 40+/-9%, abolished Hx-induced inhibition of F1Fo-ATPase activity, attenuated Hx-induced losses in F1Fo-derived ATP and protected against Hx- and reperfusion-induced cell death. A scrambled-sequence (inactive) peptide, which contained HIV-Tat and mitochondrial-targeting sequences, was without effect. In contrast, the cell-permeant mitochondrial-targeted PKCdelta-dF1Fo facilitator peptide, which we have shown previously to induce the PKCdelta-dF1Fo co-IP, was found to inhibit F1Fo-ATPase activity to an extent similar to that caused by Hx alone. The PKCdelta-dF1Fo facilitator peptide also decreased ATP levels by 72+/-18% under hypoxic conditions in the presence of glycolytic inhibition. None of the PKCdelta-dF1Fo modulatory peptides altered the inner mitochondrial membrane potential. Our studies provide the first evidence that disruption of the PKCdelta-dF1Fo interaction using cell-permeant mitochondrial-targeted peptides attenuates cardiac injury resulting from prolonged oxygen deprivation.
authors.affiliation: Department of Pharmacology and Toxicology, School of Medicine, Medical College of Georgia, Augusta, GA 30912-2300, USA.
authors.forename: Tiffany T
authors.initials: TT
authors.lastname: Nguyen
authors.forename: Mourad
authors.initials: M
authors.lastname: Ogbi
authors.forename: Qilin
authors.initials: Q
authors.lastname: Yu
authors.forename: John A
authors.initials: JA
authors.lastname: Johnson
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D015687:Cell Hypoxia / Q000502:physiology; D002470:Cell Survival / Q000187:drug effects; D004734:Energy Metabolism; D066298:In Vitro Techniques; D007476:Ionophores / Q000494:pharmacology; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008929:Mitochondria, Heart / Q000187:drug effects / Q000378:metabolism; D025261:Mitochondrial Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology; D011485:Protein Binding; D051745:Protein Kinase C-delta / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D021122:Protein Subunits; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D007476:Ionophores; D010446:Peptide Fragments; D021122:Protein Subunits; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D000255:Adenosine Triphosphate; C497260:Prkcd protein, rat; D051745:Protein Kinase C-delta; D025261:Mitochondrial Proton-Translocating ATPases