Activation of cardiac AMP-activated protein kinase by LKB1 expression or chemical hypoxia is blunted by increased Akt activity
Activation of cardiac AMP-activated protein kinase by LKB1 expression or chemical hypoxia is blunted by increased Akt activity
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DOI：
10.1152/ajpheart.01206.2005
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发表时间：
2006-06-01
影响因子：
4.8
通讯作者：
Dyck, Jason R. B.
中科院分区：
文献类型：
--
作者：
Soltys, Carrie-Lynn M.;Kovacic, Suzanne;Dyck, Jason R. B.
amp活化蛋白激酶（AMPK）在调节心脏能量底物利用中起主要作用，可受Akt在心脏中的激活负调控。最近的研究表明，Akt在体外直接磷酸化Ser485/491上的AMPK α (1)/ α(2)，并阻止AMPK激酶（=AMPKK） LKB1磷酸化AMPK α的主要激活位点Thr172 （S Horman, D Vertommen, R Heath, D Neumann, V Mouton, A Woods, U Schlattner, T Wallimann, D Carling， L Hue和MH Rider）。生物化学杂志，2006)。为了确定心肌细胞是否也存在这种情况，用表达Akt1组成型活性突变体（myrAkt1）的重组腺病毒感染新生大鼠心肌细胞（NRCM），然后用或不用表达活性LKB1复合物的腺病毒感染。myrAkt1的表达减弱了lkb诱导的AMPK α Thr172位点的磷酸化，从而导致AMPK靶点乙酰辅酶a羧化酶的磷酸化显著降低。AMPK活性的降低与先前akt1依赖性的AMPK α 1/ α 2在Ser485/491位点的磷酸化有关。为了研究Akt1激活是否也能够阻止其他AMPKKs磷酸化AMPK α，我们将NRCM置于化学缺氧状态，并注意到AMPK α在Thr172位点的磷酸化显著增加，尽管LKB1活性没有变化。表达myrAkt1的NRCM显示AMPK α 1/ α 2 Ser485/491位点磷酸化增加，并且完全抑制化学缺氧诱导的AMPK α Thr172位点磷酸化。综上所述，我们的数据表明，Akt1的激活能够阻止LKB1和至少一种其他AMPKK对心脏AMPK的激活，这可能是由于AMPK α 1/ α 2在Ser485/491位点的先前磷酸化。
AMP-activated protein kinase (AMPK) plays a major role in the regulation of cardiac energy substrate utilization and can be negatively regulated by Akt activation in the heart. It has recently been shown that Akt directly phosphorylates AMPK alpha(1)/alpha(2) on Ser485/491 in vitro and prevents the AMPK kinase ( =AMPKK) LKB1 from phosphorylating AMPK alpha at its primary activation site, Thr172 (S Horman, D Vertommen, R Heath, D Neumann, V Mouton, A Woods, U Schlattner, T Wallimann, D Carling, L Hue, and MH Rider. J Biol Chem 281: 5335-5340, 2006). To determine whether this is also the case in the cardiac myocyte, neonatal rat cardiac myocytes (NRCM) were infected with a recombinant adenovirus expressing a constitutively active mutant of Akt1 (myrAkt1) and then with or without adenoviruses expressing the active LKB1 complex. Expression of myrAkt1 blunted LKB-induced phosphorylation of AMPK alpha at Thr172, which resulted in a dramatic decrease in phosphorylation of AMPK's target, acetyl CoA-carboxylase. This decrease in AMPK activity was associated with prior Akt1-dependent phosphorylation of AMPK alpha 1/alpha 2 at Ser485/491. To investigate whether Akt1 activation was also able to prevent other AMPKKs from phosphorylating AMPK alpha, we subjected NRCM to chemical hypoxia and noted a marked increase in phosphorylation of AMPK alpha at Thr172, despite no change in LKB1 activity. NRCM expressing myrAkt1 demonstrated increased phosphorylation of AMPK alpha 1/alpha 2 at Ser485/491 and a complete inhibition of chemical hypoxia-induced phosphorylation of AMPK alpha at Thr172. Taken together, our data show that activation of Akt1 is able to prevent activation of cardiac AMPK by LKB1 and at least one other AMPKK, likely by prior phosphorylation of AMPK alpha 1/alpha 2 at Ser485/491.