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