Mechanical stretch activates signaling events for protein translation initiation and elongation in C2C12 myoblasts
Mechanical stretch activates signaling events for protein translation initiation and elongation in C2C12 myoblasts
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DOI：
10.1007/s10059-010-0147-3
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发表时间：
2010-12-01
影响因子：
3.8
通讯作者：
Ohira, Yoshinobu
中科院分区：
文献类型：
--
作者：
Nakai, Naoya;Kawano, Fuminori;Ohira, Yoshinobu
有人提出，机械诱导的张力是诱导肌肉肥大的关键因素。然而，参与这一过程的分子机制仍在研究中。在本研究中，我们研究了机械拉伸对C2C12成肌细胞内蛋白质翻译起始和延伸信号的影响。细胞在硅胶弹性体室中生长，并进行30分钟5%或15%的恒定静态或循环（60次/分钟）单轴拉伸。Western blot分析显示，作为翻译起始和肽链延伸标记的p70s6激酶（p70S6K）和真核延伸因子2 （eEF2）分别被静态和循环拉伸激活。15%循环拉伸的激活幅度更大。循环拉伸也增加了MAP激酶（p38 MAPK， ERK1/2和JNK）的磷酸化。然而，MAP激酶的药理抑制并不能阻断拉伸诱导的p70S6K和eEF2的激活。哺乳动物雷帕霉素靶蛋白（mTOR）的抑制剂阻断了拉伸诱导的p70S6K磷酸化，但不影响eEF2的激活。一种广谱酪氨酸激酶抑制剂染料木素可以阻断拉伸诱导的p70S6K和eEF2的激活，而Src酪氨酸激酶和Janus激酶（JAK）抑制剂则没有。这些结果表明，拉伸诱导的小鼠成肌细胞蛋白翻译起始和延伸激活是由酪氨酸激酶介导的，除了Src激酶或JAK激酶。
It has been proposed that mechanically induced tension is the critical factor in the induction of muscle hypertrophy. However, the molecular mechanisms involved in this process are still under investigation. In the present study, the effect of mechanical stretch on intracellular signaling for protein translation initiation and elongation was studied in C2C12 myoblasts. Cells were grown on a silicone elastomer chamber and subjected to 30-min of 5 or 15% constant static or cyclic (60 cycles/min) uniaxial stretch. Western blot analyses revealed that p70 S6 kinase (p70S6K) and eukaryotic elongation factor 2 (eEF2), which are the markers for translation initiation and peptide chain elongation, respectively, were activated by both static and cyclic stretch. The magnitude of activation was greater in response to the 15% cyclic stretch. Cyclic stretch also increased the phosphorylation of MAP kinases (p38 MAPK, ERK1/2 and JNK). However, the pharmacological inhibition of MAP kinases did not block the stretch-induced activation of p70S6K and eEF2. An inhibitor of the mammalian target of rapamycin (mTOR) blocked the stretch-induced phosphorylation of p70S6K but did not affect the eEF2 activation. A broad-range tyrosine kinase inhibitor, genistein, blocked the stretch-induced activation of p70S6K and eEF2, whereas Src tyrosine kinase and Janus kinase (JAK) inhibitors did not. These results suggest that the stretch-induced activation of protein translation initiation and elongation in mouse myoblast cell lines is mediated by tyrosine kinase(s), except for Src kinase or JAK.