Dual activation of STAT-3 and Akt is required during the trigger phase of ischaemic preconditioning
Dual activation of STAT-3 and Akt is required during the trigger phase of ischaemic preconditioning
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DOI：
10.1093/cvr/cvn067
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发表时间：
2008-07-01
影响因子：
10.8
通讯作者：
Lecour, Sandrine C.
中科院分区：
文献类型：
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作者：
Suleman, Naushaad;Somers, Sarin;Lecour, Sandrine C.
在肿瘤坏死因子- α (TNF - α)预处理过程中，信号换能器和转录激活因子-3 （STAT-3）的激活而不是Akt的激活是必不可少的，而缺血心脏预处理（IPC）在再灌注时需要STAT-3和Akt的激活。然而，在预处理刺激（触发阶段）中是否发生相同的信号传导模式以及STAT-3和Akt之间是否存在联系尚不清楚。因此，我们的假设是，在IPC的触发阶段，这两个关键信号之间需要同时激活或共同作用。相反，我们提出当TNF α (TNF- pc)诱导预处理时不会出现这种相互作用。方法和结果从成年野生型（WT）和心脏特异性STAT-3敲除（KO）小鼠中分离心肌细胞，暴露于模拟缺血（SI）再灌注。在AG490 （100 nM）或wortmannin （100 nM）存在或不存在的情况下，分别用30 min SI或30 min TNF α (0.5 ng/mL)对细胞进行预处理，以抑制STAT-3或Akt。台盼蓝法检测细胞活力，Western blot检测STAT-3和Akt磷酸化水平。在缺血再灌注损伤的离体大鼠心脏中进行了类似的实验。这两种预处理刺激都不能保护KO心肌细胞，而添加AG490可以消除WT心肌细胞或离体心脏的预处理。Wortmannin取消了IPC提供的保护，但对两种模型的TNF-PC没有影响。Western blot分析显示，在IPC刺激下添加wortmannin降低了STAT-3的磷酸化，相反，AG490降低了Akt的磷酸化。结论TNF-PC过程中STAT-3的激活不依赖于Akt。相反，在IPC刺激过程中，两种促生存信号分子级联反应协同作用，抑制STAT-3的激活也抑制Akt的激活，反之亦然。
Aims During preconditioning by tumour necrosis factor-alpha (TNF alpha), activation of the signal transducer and activator of transcription-3 (STAT-3) but not Akt, is essential, whereas ischaemic cardiac preconditioning (IPC) requires both STAT-3 and Akt at the time of reperfusion. However, it is not known whether the same signalling pattern occurs during the preconditioning stimulus (trigger phase) and whether links exist between STAT-3 and Akt. Hence, our hypothesis is that concomitant activation or co-interaction between these two key signals is required during the trigger phase for IPC. Conversely, we proposed that there would be no such interaction when preconditioning was induced by TNF alpha (TNF-PC).Methods and results Cardiomyocytes, isolated from adult wild-type (WT) and cardiac-specific STAT-3 knockout (KO) mice, were exposed to simulated ischaemia (SI) reperfusion. Cells were preconditioned either by 30 min SI or by 30 min TNF alpha (0.5 ng/mL) in the presence or absence of AG490 (100 nM) or wortmannin (100 nM) to inhibit STAT-3 or Akt, respectively. Cell viability was evaluated by trypan blue, and phosphorylation levels of STAT-3 and Akt were measured by Western blot analysis. Similar experiments were conducted in isolated rat hearts subjected to an ischaemia-reperfusion insult. Both preconditioning stimuli failed to protect KO cardiomyocytes, and addition of AG490 abolished preconditioning in WT cardiomyocytes or isolated hearts. Wortmannin abolished the protection afforded by IPC, but did not affect TNF-PC in both models. Western blot analysis demonstrated that added wortmannin during IPC stimulus decreased STAT-3 phosphorylation while, conversely, AG490 reduced Akt phosphorylation.Conclusion STAT-3 activation could be achieved independent of Akt during TNF-PC. In contrast, during an IPC stimulus, both prosurvival signalling molecule cascades acted in concert so that inhibiting activation of STAT-3 also inhibited that of Akt and vice versa.