An Inhibitor of p38 Mitogen-activated Protein Kinase Protects Neonatal Cardiac Myocytes from Ischemia

Abstract

Cellular ischemia results in activation of a number of kinases, including p38 mitogen-activated protein kinase (MAPK); however, it is not yet clear whether p38 MAPK activation plays a role in cellular damage or is part of a protective response against ischemia. We have developed a model to study ischemia in cultured neonatal rat cardiac myocytes. In this model, two distinct phases of p38 MAPK activation were observed during ischemia. The first phase began within 10 min and lasted less than 1 h, and the second began after 2 h and lasted throughout the ischemic period. Similar to previous studies using in vivo models, the nonspecific activator of p38 MAPK and c-Jun NH 2 -terminal kinase, anisomycin, protected cardiac myocytes from ischemic injury, decreasing the release of cytosolic lactate dehydrogenase by approximately 25%. We demonstrated, however, that a selective inhibitor of p38 MAPK, SB 203580, also protected cardiac myocytes against extended ischemia in a dose-dependent manner. The protective effect was seen even when the inhibitor was present during only the second, sustained phase of p38 MAPK activation. We found that ischemia induced apoptosis in neonatal rat cardiac myocytes and that SB 203580 reduced activation of caspase-3, a key event in apoptosis. These results suggest that p38 MAPK induces apoptosis during ischemia in cardiac myocytes and that selective inhibition of p38 MAPK could be developed as a potential therapy for ischemic heart disease.The heart is subjected to episodes of ischemia followed by reperfusion in a number of situations, including angina, myocardial infarction, and cardiac surgery, and these stresses can result in cell injury and death. Part of the cellular response to ischemia/reperfusion is activation of several members of the mitogen-activated protein kinase (MAPK) 1 family. In many different cell types, p38 MAPK and c-Jun NH 2 -terminal kinase (JNK) family members are activated predominantly by cellular stresses or inflammatory signals, e.g. hyperosmolarity, chemical or heat stress, endotoxin, and cytokines (1-4), whereas the extracellular signal-regulated kinases (ERKs) are activated by mitogenic stimuli (5).In the isolated perfused rat heart, p38 MAPK is activated by global ischemia, and activation is maintained during reperfusion (6, 7). In the same model, neither ERKs nor JNKs are activated by ischemia, whereas reperfusion after ischemia activates JNK (6 -8). Different studies have shown activation (8) or lack of activation (6) of ERKs on reperfusion, possibly the result of different assay methods. More recently, it was observed that although JNK1 (also termed JNK46) is not activated by ischemia, this stress results in translocation of JNK1 to the nucleus, where it is then phosphorylated and activated on reperfusion (9). Ischemia and reperfusion also activate members of the MAPK family in kidney and liver differentially (7, 10, 11). However it is not clear from these studies whether activation of these kinases is part of the protective response of the cell or if these si...

Anisomycin protects cortical neurons from prolonged hypoxia with differential regulation of p38 and ERK

“…These data suggest that anisomycin at a low concentration is neuroprotective against conditions of hypoxia and DOR inhibition via a down-regulation of p38. The anisomycin induced protection is consistent with that seen in other cells under stress, e.g., PC 12 cells with KCl deprivation (Kharlamov et al, 1995), and cardiac myocytes under hypoxia (Mackay and Mochly-Rosen, 1999) in which anisomycin protects cells from environmental stress. This however raises several intriguing questions regarding how anisomycin, a putative p38 activator, could induce neuroprotection against stress.…”

“…The anisomycin-induced protection is also seen in other cells under stress, e.g., PC 12 cells with KCl deprivation (Kharlamov et al, 1995), and cardiac myocytes under hypoxia (Mackay and Mochly-Rosen, 1999). Such protection, we believe, is less likely mediated by an increase in p38 activity although anisomycin is thought to be a p38 activator (Shifrin and Anderson, 1999).…”

MAPKAPK-2 modulates p38-MAPK localization and small heat shock protein phosphorylation but does not mediate the injury associated with p38-MAPK activation during myocardial ischemia

“…Thus, the effects of MK2 deficiency may be underestimated due to the confounding effects on p38 MAPK content. Since ischemic activation of p38 MAPK is thought to contribute to myocardial injury (Saurin et al 2000;Mackay and Mochly-Rosen 1999;Ma et al 1999), the reduced p38 MAPK expression would be expected to attenuate ischemic damage. Although total p38 MAPK was reduced, activation was readily detectable, and the relative amount of p38 MAPK phosphorylation in response to ischemia (as percent of baseline) was similar in MK2 −/− and MK2 +/+ hearts.…”

Inhibition of p38 mitogen-activated protein kinase attenuates left ventricular dysfunction by mediating pro-inflammatory cardiac cytokine levels in a mouse model of diabetes mellitus

“…the p38 MAPK, play a pivotal role in the development of heart failure, including diabetic cardiomyopathy [10]. Via its signalling cascade, the p38 MAPK modulates genes that regulate myocyte apoptosis, cellular hypertrophy, cardiac fibrosis, and cardiac cytokine-mediated inflammation [11][12][13]. Because the p38 MAPK is not only upregulated and phosphorylated by ischaemia [14], but also, for example, by angiotensin II [15], oxidative stress [16], and high glucose levels [10], inhibition of p38 MAPK could be a potent new therapeutic option for treatment of diabetic cardiomyopathy.…”