title: δPKC interaction with the d subunit of F1Fo ATP synthase impairs energetics and exacerbates ischemia/reperfusion injury in isolated rat hearts.
abstract: Previously, we demonstrated protection against hypoxic injury in neonatal cardiac myocytes and reduced release of cardiac troponin I from perfused rat hearts by a novel peptide inhibitor [NH2-YGRKKRRQRRRMLATRALSLIGKRAISTSVCAGRKLALKTIDWVSFDYKDDDDK-] of the delta protein kinase C (δPKC) interaction with the "d" subunit of mitochondrial F1Fo ATP synthase (dF1Fo). This peptide was developed in our laboratory and contains: an HIV-Tat protein transduction domain; a mitochondrial targeting motif; the δPKC-dF1Fo inhibitor sequence; and a FLAG epitope. In the present study the δPKC-dF1Fo inhibitor attenuated co-immunoprecipitation of δPKC with dF1Fo, improved recovery of contractility, diminished levels of tissue t-carbonyls and 4-hydroxy-2-nonenal (HNE), and reduced 2,3,5-triphenyltetrazolium chloride-monitored infarct size following simulated global ischemia/reperfusion (IR) exposures. Perfusion of hearts with this peptide prior to IR enhanced ATP levels 2.1-fold, improved ADP (state 3)- and FCCP (maximal)-stimulated respiration in mitochondrial oxygen consumption assays, and attenuated Ca(++)-induced mitochondrial swelling following ischemic injury. Mitochondrial membrane potential (assessed by JC-1) was also improved 1.6-fold by the inhibitor in hearts subsequently exposed to IR injury. Brief IR exposures did not cause mitochondrial loss of cytochrome c in the presence or absence of the inhibitor. Additionally, the inhibitor did not modify accumulation of the autophagy marker LC3II after brief IR injury. Our results support the potential for this first-in-class peptide as a translational agent for combating cardiac IR injury.
authors.affiliation: Department of Pharmacology & Toxicology, Georgia Regents University, Augusta, GA 30912-2300, United States.
authors.forename: Matthew
authors.initials: M
authors.lastname: Walker
authors.affiliation: Department of Pharmacology & Toxicology, Georgia Regents University, Augusta, GA 30912-2300, United States.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Caldwell
authors.affiliation: Department of Physiology, Georgia Regents University, Augusta, GA 30912-2300, United States.
authors.forename: Yisang
authors.initials: Y
authors.lastname: Yoon
authors.affiliation: Department of Pathology, Walter Reed National Military Medical Center, Bethesda, MD 20889, United States.
authors.forename: Tiffany T
authors.initials: TT
authors.lastname: Nguyen
authors.affiliation: Department of Pharmacology & Toxicology, Georgia Regents University, Augusta, GA 30912-2300, United States. Electronic address: jjohnson@gru.edu.
authors.forename: John A
authors.initials: JA
authors.lastname: Johnson
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D019069:Cell Respiration / Q000187:drug effects; D004734:Energy Metabolism / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D047468:Immunoprecipitation; D066298:In Vitro Techniques; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D025261:Mitochondrial Proton-Translocating ATPases / Q000378:metabolism*; D009200:Myocardial Contraction / Q000187:drug effects; D015428:Myocardial Reperfusion Injury / Q000201:enzymology* / Q000473:pathology* / Q000503:physiopathology; D009206:Myocardium / Q000201:enzymology / Q000473:pathology*; D018384:Oxidative Stress / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D051745:Protein Kinase C-delta / Q000378:metabolism*; D021122:Protein Subunits / Q000378:metabolism*; D017207:Rats, Sprague-Dawley
chemical_list: D004791:Enzyme Inhibitors; D021122:Protein Subunits; D000255:Adenosine Triphosphate; D051745:Protein Kinase C-delta; D025261:Mitochondrial Proton-Translocating ATPases
keywords: Cardiac; F(1)Fo ATP synthase; HIV-Tat protein transduction domain; Ischemia/reperfusion; Mitochondrial targeting sequence; Protein kinase C