Alpha1 catalytic subunit of AMPK modulates contractile function of cardiomyocytes through phosphorylation of troponin I.
Alpha1 catalytic subunit of AMPK modulates contractile function of cardiomyocytes through phosphorylation of troponin I.
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DOI：
10.1016/j.lfs.2014.01.006
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发表时间：
2014-03-11
期刊：
影响因子：
6.1
通讯作者：
Li J
中科院分区：
文献类型：
--
作者：
Chen S;Zhu P;Guo HM;Solis RS;Wang Y;Ma Y;Wang J;Gao J;Chen JM;Ge Y;Zhuang J;Li J
AMPKα1或AMPKα2在介导心肌细胞收缩功能中的具体作用仍不清楚。本研究探讨了AMPK激活如何调节分离的心肌细胞的收缩特性。测定分离的心肌细胞的力学特性和细胞内钙离子特性。用免疫印迹和免疫沉淀分析方法对应激信号进行评估。AMPK激动剂A-769662可诱导WT和AMPKα2 KO心肌细胞的最大缩短速度(+dL/dt)和再延长速度(dL/dt)、峰高和峰缩短幅度(PS)，但不影响恢复至90%的时间(TR90)。与WT和AMPKα2 KO心肌细胞相比，AMPK KD心肌细胞表现出收缩功能障碍。然而，WT组、AMPKα2 KO组和AMPK KD组在有无A-769662存在的情况下，细胞内钙离子水平和细胞内三磷酸腺苷水平的升高没有显著差异。此外，WT组、AMPKα2 KO组和AMPK KD组表现出磷酸化的AMPK和下游的乙酰辅酶A羧化酶(Acc)磷酸化。有趣的是，A-769662还触发了肌钙蛋白I(CTnI)在Ser149位的磷酸化，这与心肌细胞的收缩能力有关。进一步的免疫沉淀分析表明，心肌细胞AMPKα1被A-769662磷酸化。这是利用转基因动物模型首次证明AMPK的激活在介导心肌细胞收缩功能中起重要作用。AMPK激活剂通过激活AMPKα1催化亚基促进心肌细胞收缩。AMPK对cTnI的磷酸化可能是调节心肌细胞收缩能力的一个因素。
The specific role of AMPKα1 or AMPKα2 in mediating cardiomyocyte contractile function remains elusive. The present study investigated how AMPK activation modulates the contractility of isolated cardiomyocytes. Mechanical properties and intracellular Ca2+ properties were measured in isolated cardiomyocytes. The stress signaling was evaluated using western blot and immunoprecipitation analysis. AMPK activator, A-769662 induced maximal velocity of shortening (+dL/dt) and relengthening (−dL/dt), peak height and peak shortening (PS) amplitude in both WT and AMPKα2 KO cardiomyocytes, but did not affect time-to-90% relengthening (TR90). AMPK KD cardiomyocytes demonstrated contractile dysfunction compared with cardiomyocytes from WT and AMPKα2 KO hearts. However, the rise of intracellular Ca2+ levels as well as intracellular ATP levels has no significant difference among WT, AMPKα2 KO and AMPK KD groups with and without the presence of A-769662. Besides, WT, AMPKα2 KO and AMPK KD group displayed a phosphorylated AMPK and downstream acetyl-CoA carboxylase (ACC) phosphorylation. Interestingly, A-769662 also triggered troponin I (cTnI) phosphorylation at Ser149 site which is related to contractility of cardiomyocytes. Furthermore, the immunoprecipitation analysis revealed that AMPKα1 of cardiomyocytes was phosphorylated by A-769662. This is the first study illustrating that activation of AMPK plays a significant role in mediating the contractile function of cardiomyocytes using transgenic animal models. AMPK activator facilitates the contractility of cardiomyocytes via activating AMPKα1 catalytic subunit. The phosphorylation of cTnI by AMPK could be a factor attributing to the regulation of contractility of cardiomyocytes.