Attenuation of the hypoxia-induced protein kinase Cδ interaction with the 'd' subunit of F1Fo-ATP synthase in neonatal cardiac myocytes: Implications for energy preservation and survival

Tiffany T. Nguyen, Mourad Ogbi, Qilin Yu, John A. Johnson

Research output: Contribution to journalArticle

8 Scopus citations

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 F1F o-ATP synthase function mediated by the interaction of PKCδ (protein kinase Cδ) with dF1Fo ('d' subunit of the F1Fo-ATPase/ATP synthase). We have now developed novel peptide modulators which facilitate or inhibit the PKCδ-dF 1Fo 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 PKCδ-dF1Fo interaction inhibitor decreased Hx (hypoxia)-induced co-IP (co-immunoprecipitation) of PKCδ with dF 1Fo 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 PKCδ-dF 1Fo facilitator peptide, which we have shown previously to induce the PKCδ-dF1Fo co-IP, was found to inhibit F1Fo-ATPase activity to an extent similar to that caused by Hx alone. The PKCδ-dF1Fo facilitator peptide also decreased ATP levels by 72±18% under hypoxic conditions in the presence of glycolytic inhibition. None of the PKCδ-dF1Fo modulatory peptides altered the inner mitochondrial membrane potential. Our studies provide the first evidence that disruption of the PKCδ-dF 1Fo interaction using cell-permeant mitochondrial-targeted peptides attenuates cardiac injury resulting from prolonged oxygen deprivation.

Original languageEnglish (US)
Pages (from-to)335-345
Number of pages11
JournalBiochemical Journal
Volume429
Issue number2
DOIs
StatePublished - Jul 15 2010
Externally publishedYes

Keywords

  • Cardiac injury
  • FF-ATP synthase
  • Hypoxia
  • Mitochondrion
  • Oxidative phosphorylation
  • Protein kinase C (PKC)

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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