Myocardial Ca 2+ overload induced by ischemia/reperfusion (I/R) is a major element of myocardial dysfunction in heart failure. Phospholipase C (PLC) plays important roles in the regulation of the phosphoinositol pathway and Ca 2+ homeostasis in various types of cells. Here, we investigated the protective role of PLCδ1 against myocardial I/R injury through the regulation of Ca 2+ homeostasis. To investigate its role, PLCδ1 was fused to Hph1, a cell-permeable protein transduction domain (PTD), and treated into rat neonatal cardiomyocytes and rat hearts under respective hypoxia-reoxygenation (H/R) and ischemia-reperfusion conditions. Treatment with Hph1-PLCδ1 significantly inhibited intracellular Ca 2+ overload, reactive oxygen species generation, mitochondrial permeability transition pore opening, and mitochondrial membrane potential elevation in H/R neonatal cardiomyocytes, resulting in the inhibition of apoptosis. Intravenous injections of Hph1-PLCδ1 in rats with I/R-injured myocardium caused significant reductions in infarct size and apoptosis and also improved systolic and diastolic cardiac functioning. Furthermore, a small ions profile obtained using time-of-flight secondary ion mass spectrometry showed that treatment with Hph1-PLCδ1 leads to significant recovery of calcium-related ions toward normal levels in I/R-injured myocardium. These results suggest that Hph1-PLCδ1 may manifest as a promising cardioprotective drug due to its inhibition of the mitochondrial apoptotic pathway in cells suffering from I/R injury.
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The authors appreciate comments and helpful feedbacks from several experts including Robert M. Graham, Sue Goo Rhee, and Im Mie-Jae. We also thank Dong-Su Jang, a research assistant in the Department of Anatomy at Yonsei University College of Medicine in Seoul, Korea, for his help with the figures. This research was supported by a Korea Science and Engineering Foundation grant funded by the Korean government (MEST) (2011-0019243, 2011-0019254), a grant from the Korea Health 21 R&D Project, Ministry of Health & Welfare, Republic of Korea (A120478), and a grant from the Korea Health 21 R&D Project, Ministry of Health & Welfare, Republic of Korea (HI08C2149). All authors have declared that there are no conflicts of interests.
All Science Journal Classification (ASJC) codes
- Molecular Medicine
- Molecular Biology
- Drug Discovery