Journal List > Korean Circ J > v.37(7) > 1016236

Yoo, Lee, Jang, Kim, Lee, Park, Lim, Kwon, Cho, and Kim: Protection of Cardiomyocytes from Acute Ischemic Injury by Protein Kinase Cε Expression

Abstract

Background and Objectives

Ischemic injury is the most common and important cause of myocardial damage. Over past decades, a number of studies have identified a protective mechanism known as ischemic preconditioning, which can block or delay cell death from ischemic injury. Protein kinase C (PKC), especially the ε isoform has been proposed as a key factor in the signaling pathway of ischemic preconditioning. However, whether PKCε expression in cardiomyocytes can offer such protection from acute ischemia has not been explored.

Materials and Methods

To demonstrate a direct effect of PKCε expression, a lentiviral vector system was established. Using the lentiviral vector, PKCε was introduced to neonatal rat ventricular myocytes (NRVM) cultured under ischemic conditions, and also to adult rat myocardium subject to left coronary artery ligation.

Results

Compared to control, PKCε expression in cultured NRVM under ischemia resulted in preserved cell density and morphology, and a reduction in cell death (77.6±12.8% vs 58.1±7.2%, p<0.05). In adult rats, the infarcted area after coronary artery ligation was markedly reduced in myocardium injected with PKCε vector compared to control (11.4±5.3% vs 20.5±11.3%, p<0.01).

Conclusion

These results provide direct evidence that PKCε is a central player in protection against cell death from acute ischemia.

Figures and Tables

Fig. 1
Microscopic findings of neonatal rat ventricular myocyte (NRVM) cultured under various conditions. Control: NRVM cultured under normal condition, Ischemia: NRVM cultured under ischemic condition, Ischemia+TPA: NRVM cultured under ischemic condition treated with tetradecanoylphorbol 13-acetate (TPA), Ischemia+vector: NRVM culuted under ischemic condition treated with empty vetor, Ischemia+vector+TPA: NRVM cultured under ischemic condition treated with empty vector and TPA, Ischemia+PKC+TPA: NRVM cultured under ischemic condition treated with protein kinase Cε vector and TPA, PKC: protein kinase C.
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Fig. 2
Comparison of cell death of cultured neonatal rat ventricular myocyte (NRVM) under various conditions. Number of cell death was determined by counting cells failing to exclude the trypan blue dye. Control: NRVM cultured under normal condition, Ischemia: NRVM cultured under ischemic condition, I+TPA: NRVM cultured under ischemic condition treated with tetradecanoylphorbol 13-acetate (TPA), I+PKC+TPA: NRVM cultured under ischemic condition treated with protein kinase Cε vector and TPA. *: p<0.05 between ischemia and ischemia+PKC+TPA, PKC: protein kinase C.
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Fig. 3
Representative samples of transverse section of myocardium stained with phthalocyanin blue and triphenyltetrazolium chloride in control and treated rat heart, injected with PKCε lentiviral vector intramuscularly. Unstainted area (white color) represents infarcted myocardium. PKCε: protein kinase Cε.
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Fig. 4
Bar graphs represent area of infarction between control and treated rat heart, injected with PKCε lentiviral vector intramuscularly. Control MI: rat heart injected with control buffer 4 days prior to left coronary artery ligation, PKCε MI: rat heart injected with PKCε vector 4 days prior to left coronary artery ligation. PKCε: protein kinase Cε, MI: myocardial infarction
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Acknowledgments

We are deeply grateful to professor Yoshitaka Ono of Biosignal Research Center, Kobe University, for the generous gift of PKCε cDNA, which enables us to conduct this study.

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