کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1904849 1534671 2013 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Differential regulation of eEF2 and p70S6K by AMPKalpha2 in heart
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی سالمندی
پیش نمایش صفحه اول مقاله
Differential regulation of eEF2 and p70S6K by AMPKalpha2 in heart
چکیده انگلیسی


• We genetically prove that cardiac AMPKα2 inhibits eEF2 during myocardial ischemia.
• AMPKα2 is not required for p70S6K inhibition during ischemia.
• This challenges the accepted notion that p70S6K inhibition by ischemia is due to AMPK.
• In normoxia, cardiac AMPKα2 puts a brake on p70S6K via Raptor.

Eukaryotic elongation factor 2 (eEF-2) and mammalian target of rapamycin (mTOR)–p70 ribosomal protein S6 kinase (p70S6K) signaling pathways control protein synthesis and are inhibited during myocardial ischemia. Intracellular acidosis and AMP-activated protein kinase (AMPK) activation, both occurring during ischemia, have been proposed to participate in this inhibition. We evaluated the contribution of AMPKα2, the main cardiac AMPK catalytic subunit isoform, in eEF2 and mTOR–p70S6K regulation using AMPKα2 KO mice. Hearts were perfused ex vivo with or without insulin, and then submitted or not to ischemia. Insulin pre-incubation was necessary to activate mTOR–p70S6K and evaluate their subsequent inhibition by ischemia. Ischemia decreased insulin-induced mTOR–p70S6K phosphorylation in WT and AMPKα2 KO mice to a similar extent. This AMPKα2-independent p70S6K inhibition correlated well with the inhibition of PKB/Akt, located upstream of mTOR–p70S6K and can be mimicked in cardiomyocytes by decreasing pH. By contrast, ischemia-induced inhibitory phosphorylation of eEF-2 was drastically reduced in AMPKα2 KO mice. Interestingly, AMPKα2 also played a role under normoxia. Its deletion increased the insulin-induced p70S6K stimulation. This p70S6K over-stimulation was associated with a decrease in inhibitory phosphorylation of Raptor, an mTOR partner identified as an AMPK target. In conclusion, AMPKα2 controls cardiac p70S6K under normoxia and regulates eEF-2 but not the mTOR–p70S6K pathway during ischemia. This challenges the accepted notion that mTOR–p70S6K is inhibited by myocardial ischemia mainly via an AMPK-dependent mechanism.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease - Volume 1832, Issue 6, June 2013, Pages 780–790
نویسندگان
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