Mechanism of activation of dsRNA-dependent protein kinase (PKR) in muscle atrophy
Mechanism of activation of dsRNA-dependent protein kinase (PKR) in muscle atrophy
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DOI：
10.1016/j.cellsig.2010.01.002
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发表时间：
2010-05-01
影响因子：
4.8
通讯作者：
Tisdale, M. J.
中科院分区：
文献类型：
--
作者：
Eley, H. L.;Russell, S. T.;Tisdale, M. J.
使用细胞渗透性 Ca2+ 螯合剂 BAPTA/AM（1,2-双（邻氨基苯氧基）乙烷-N,N,N',N'-四乙酸四（乙酰氧基甲基）酯）在小鼠肌管中研究了 Ca2+ 在 PKR（双链 RNA 依赖性蛋白激酶）激活中的作用，PKR 会导致骨骼肌萎缩。 BAPTA/AM 通过泛素-蛋白酶体途径有效减弱总蛋白质降解的增加，以及由蛋白水解诱导因子 (PIF) 和血管紧张素 II (Ang II) 诱导的蛋白质合成抑制。由于蛋白质合成和降解均减弱，这表明 PKR 的参与。事实上，在 PIF 存在的情况下，BAPTA/AM 减弱了 PKR 的激活（自磷酸化）以及随后的 eIF2 α（真核起始因子 2 α）的磷酸化，表明 Ca2+ 参与了这一过程。 PIF 还诱导 caspase-3 和 -8 活性增加，但 BAPTA/AM 减弱了这种活性。 caspase-3 和 -8 活性的增加被证明是 PKR 激活的原因，因为后者被特定的 caspase-3 和 -8 抑制剂完全减弱。这些结果表明，Ca2+ 通过 caspase-3 和 -8 激活 PKR，参与 PIF 和 Ang II 蛋白质降解的增加和蛋白质合成的减少。 (C) 2010 Elsevier Inc. 保留所有权利。
The role of Ca2+ in the activation of PKR (double-stranded-RNA-dependent protein kinase), which leads to skeletal muscle atrophy, has been investigated in murine myotubes using the cell-permeable Ca2+ chelator BAPTA/AM (1,2-bis (o-aminphenoxy) ethane-N,N,N',N'-tetraacetic acid tetra (acetoxymethyl) ester). BAPTA/AM effectively attenuated both the increase in total protein degradation, through the ubiquitin-proteasome pathway, and the depression of protein synthesis, induced by both proteolysis-inducing factor (PIF) and angiotensin II (Ang II). Since both protein synthesis and degradation were attenuated this suggests the involvement of PKR. Indeed BAPTA/AM attenuated both the activation (autophosphorylation) of PKR and the subsequent phosphorylation of eIF2 alpha (eukaryotic initiation factor 2 alpha) in the presence of PIF, suggesting the involvement of Ca2+ in this process. PIF also induced an increase in the activity of both caspases-3 and -8, which was attenuated by BAPTA/AM. The increase in caspase-3 and -8 activity was shown to be responsible for the activation of PKR, since the latter was completely attenuated by the specific caspase-3 and -8 inhibitors. These results suggest that Ca2+ is involved in the increase in protein degradation and decrease in protein synthesis by PIF and Ang II through activation of PKR by caspases-3 and -8. (C) 2010 Elsevier Inc. All rights reserved.