Preconditioning attenuates apoptosis and necrosis: role of protein kinase Cε and -δ isoforms

Abstract

Preconditioning reduces cardiomyocyte necrosis in vivo and in vitro, but it is unknown whether preconditioning blocks apoptosis. We wanted to compare the effects of preconditioning on necrosis and apoptosis in cardiomyocytes. Necrosis was detected with propidium iodide, and apoptosis was quantified by three complementary techniques: flow cytometry, TdT-mediated dUTP nick-end labeling assay, and DNA-laddering electrophoresis. Apoptosis increased with simulated ischemia time (6 h, 19 +/- 1%; 12 h, 27 +/- 2%; 18 h, 40 +/- 4%; 24 h, 54 +/- 4%; and 36 h, 83 +/- 4%; n = 6 for each group). Simulated ischemia and reoxygenation contributed equally to apoptosis (12-h ischemia, 27 +/- 2%, n = 6; 12-h ischemia and 12-h reoxygenation, 51 +/- 4%, n = 6; and 24-h ischemia, 54 +/- 5%, n = 8). Necrosis occurred primarily during reoxygenation; none was detected during simulated ischemia. Preconditioning with 10 min of simulated ischemia reduced necrosis (18 +/- 6%, n = 8) but had no effect on apoptosis. However, three 1-min cycles of simulated ischemia separated by 5 min of reoxygenation reduced necrosis and apoptosis similarly. The protein kinase C (PKC) inhibitors Go6976 (0.1 microM) or chelerythrene (4 microM) abolished the effect of preconditioning. Preconditioning selectively activated PKC epsilon but had no effect on PKC delta and on total PKC enzyme activity. Preconditioning protected against necrosis and apoptosis, but the preconditioning ischemia required for blocking apoptosis was less than that for reducing necrosis. Activation of PKC epsilon isoform is important in mediating the protection.

Cold ischemic injury of transplanted kidneys: new insights from experimental studies

“…Moreover, the latest data suggest that PKC-␦ can be a proapoptotic molecule by functioning as a lamin kinase, disassembling lamina during apoptosis. That PKC-⑀ can be protective, whereas PKC-␦ can be destructive, is also suggested by other studies (27,39). Very few studies have been carried out examining the role of PKC during cold storage, and in one, the use of nonspecific PKC inhibitors has been shown to improve rat heart preservation (16).…”

Morphine Protects against Intracellular Amyloid Toxicity by Inducing Estradiol Release and Upregulation of Hsp70

“…brane translocations of nPKC and NMDA receptors in mouse hippocampal slices (Liu et al, 2001;Fanjun et al, 2006). It is proposed that morphine-induced nitrogen oxide release mediates neuroprotection in a human neuroblastoma cell line against intracellular oxidative stress and neuroinflammation (Rambhia et al, 2005).…”

Cardiac overexpression of A1-adenosine receptor protects intact mice against myocardial infarction

“…Our previous studies with isolated heart models have shown that A 1 -AR overexpression increases myocardial resistance to ischemia by constitutively activating endogenous signaling pathways, with mitochondrial K ATP channels being critical effectors (14,21). Because A 1 -AR-mediated cardiac protection shares at least some common mechanisms with ischemic preconditioning (17,21), it is logical that other signaling intermediates [such as protein kinase C (16,18) and tyrosine kinase] are also held in common. Recently, p38 mitogen-activated protein kinase was found to be an important signaling component in the cardioprotection induced by preconditioning and adenosine (4,7,20).…”