Sustained activation of p42/p44 mitogen-activated protein kinase during recovery from simulated ischaemia mediates adaptive cytoprotection in cardiomyocytes
Sustained activation of p42/p44 mitogen-activated protein kinase during recovery from simulated ischaemia mediates adaptive cytoprotection in cardiomyocytes
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DOI：
10.1042/0264-6021:3500891
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发表时间：
2000-09-15
影响因子：
4.1
通讯作者：
Heads, RJ
中科院分区：
文献类型：
--
作者：
Punn, A;Mockridge, JW;Heads, RJ
在亚致死模拟缺血再灌注（SI/R）后24 h，新生大鼠心室肌细胞发生延迟性细胞保护（预处理）。采用SI/R方法，观察了丝裂原活化蛋白激酶（MAPK）、应激活化蛋白激酶（SAPKs）和磷酸肌醇3激酶依赖性蛋白激酶B（PKB）/Akt的活化在细胞保护中的作用。SI导致p42/p44-MAPK和p38-MAPK的瞬时双（Thr/Tyr）磷酸化，p46/p54-SAPK的弱磷酸化，但不导致PKB的磷酸化。“再灌注”引起p38-MAPK进一步短暂磷酸化，但p42/p44-MAPK持续磷酸化（持续4 h），PKB的Ser（473）持续磷酸化（持续2 h）。此外，SI/R（24小时）诱导针对致死性SI的延迟保护，如通过细胞活力的增加{MTT [3-（4，5-二甲基噻唑基-2）-2，5-二苯基溴化四唑]的生物还原}和细胞损伤的减少（肌酸激酶的释放）所确定的。当在SI/R期间给予MEK-1/2（MAPK/Erk激酶-1/2）抑制剂PD 98059（50 μ M）时，p42/p44-MAPK的保护作用和磷酸化作用均被阻断，但当在单独SI期间给予时则不被阻断。p38-MAPK抑制剂SB 203580（10 μ M）在体外阻断了转录激活因子2的p38-MAPK依赖性磷酸化，磷酸肌醇3-激酶抑制剂wortmannin（100 nM）阻断了Ser（473）上的PKB磷酸化。然而，SB 203580和渥曼青霉素对延迟保护没有任何影响。因此，在亚致死SI后的模拟“再灌注”过程中，p42/p44-MAPK的持续激活介导了心肌细胞的预处理，而不依赖于p38-MAPK的瞬时激活或PKB的持续激活。
Delayed cytoprotection (preconditioning) occurs 24 h after sublethal simulated ischaemia and reperfusion (SI/R) in neonatal rat ventricular cardiomyocytes, SI/R was used to investigate the role of activation of mitogen-activated protein kinases (MAPKs), stress-activated protein kinases (SAPKs) and phosphoinositide 3-kinase-dependent protein kinase B (PKB)/Akt in cytoprotection. SI resulted in transient dual (Thr/Tyr) phosphorylation of p42/p44-MAPK and p38-MAPK, weak phosphorylation of p46/p54-SAPK, but no phosphorylation of PKB. 'Reperfusion' caused further transient phosphorylation of p38-MAPK, but sustained phosphorylation of p42/p44-MAPK (lasting 4 h) and of Ser(473) of PKB (lasting 2 h). Furthermore, SI/R (24h) induced delayed protection against lethal SI, as determined by an increase in cell viability {bioreduction of MTT [3-(4, 5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide]} and a decrease in cell injury (release of creatine kinase). Both protection and phosphorylation of p42/p44-MAPK were blocked by the MEK-1/2 (MAPK/Erk kinase-1/2) inhibitor PD98059 (50 mu M) when given during SI/R, but not when given during SI alone. The p38-MAPK inhibitor SB203580 (10 mu M) blocked the p38-MAPK-dependent phosphorylation of activating transcription factor 2 in vitro, and the phosphoinositide 3-kinase inhibitor wortmannin (100 nM) blocked PKB phosphorylation on Ser(473). However, neither SB203580 nor wortmannin had any effect on delayed protection. Therefore sustained activation of p42/p44-MAPK during simulated 'reperfusion' following sublethal SI mediates preconditioning in cardiomyocytes independently of transient activation of p38-MAPK or sustained activation of PKB.