Ataxia telangiectasia mutated impacts insulin-like growth factor 1 signalling in skeletal muscle
Ataxia telangiectasia mutated impacts insulin-like growth factor 1 signalling in skeletal muscle
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DOI：
10.1113/expphysiol.2012.066357
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发表时间：
2013-02-01
影响因子：
2.7
通讯作者：
Fisher, Jonathan S.
中科院分区：
文献类型：
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作者：
Ching, James Kain;Luebbert, Stephen H.;Fisher, Jonathan S.
据报道，共济失调毛细血管扩张突变 (ATM) 是 Akt 完全激活所必需的，这提出了这样的假设：ATM 通过 Akt/哺乳动物雷帕霉素靶点 (mTOR) 通路在胰岛素样生长因子 1 (IGF-1) 信号传导中发挥作用。将含有 ATM 靶向短发夹 RNA (shRNA) 或非靶向 shRNA 的分化 C2C12 细胞和来自先前暴露于空载体慢病毒的 C2C12 谱系的肌管在存在或不存在 10 nm IGF-1 的情况下孵育，然后进行蛋白质印迹分析。与野生型 (ATM(+/+)) 小鼠的肌肉相比，在仅表达一种功能性 ATM 等位基因 (ATM(+/-)) 的小鼠的分离比目鱼肌中进行了平行实验。胰岛素样生长因子 1 增加表达非靶向 shRNA 的肌管和空载体对照中 Akt S473、Akt T308 和 p70 S6 激酶 (S6K) 的磷酸化，但在 shRNA 介导的 ATM 敲低的肌管中 IGF-1 效应显着降低。同样，与 ATM(+/+) 小鼠的肌肉相比，ATM(+/-) 小鼠的离体比目鱼肌中 IGF-1 刺激的 Akt S473、Akt T308、mTOR 和 S6K 磷酸化较低。 ATM 抑制剂 KU55933 阻止了暴露于 IGF-1 的 C2C12 肌管中 S6K 磷酸化的刺激，表明 IGF-1 作用的降低并不限于 ATM 功能降低的慢性疾病。 IGF-1 对胰岛素受体底物 1 酪氨酸 612 磷酸化的刺激不受 ATM 缺陷的影响，尽管与野生型肌肉相比，ATM 单倍体不足小鼠的肌肉中 IGF-1 磷脂酰肌醇 3-激酶活性往往较低。数据表明，ATM 是骨骼肌中胰岛素受体底物 1 下游 IGF-1 信号传导的调节剂。
Reports that ataxia telangiectasia mutated (ATM) is required for full activation of Akt raise the hypothesis that ATM plays a role in insulin-like growth factor 1 (IGF-1) signalling through the Akt/mammalian target of rapamycin (mTOR) pathway. Differentiated C2C12 cells harbouring either ATM-targeting short hairpin RNA (shRNA) or non-targeting shRNA and myotubes from a C2C12 lineage previously exposed to empty vector lentivirus were incubated in the presence or absence of 10 nm IGF-1 followed by Western blot analysis. Parallel experiments were performed in isolated soleus muscles from mice expressing only one functional ATM allele (ATM(+/-)) compared with muscles from wild-type (ATM(+/+)) mice. Insulin-like growth factor 1 increased phosphorylation of Akt S473, Akt T308 and p70 S6 kinase (S6K) in myotubes expressing non-targeting shRNA and in empty vector controls, but the IGF-1 effects were significantly reduced in myotubes with shRNA-mediated ATM knockdown. Likewise, IGF-1-stimulated phosphorylation of Akt S473, Akt T308, mTOR and S6K was lower in isolated soleus muscles from ATM(+/-) mice compared with muscles from ATM(+/+) mice. The ATM inhibitor KU55933 prevented stimulation of S6K phosphorylation in C2C12 myotubes exposed to IGF-1, suggesting that decreased IGF-1 action is not limited to chronic conditions of decreased ATM function. Stimulation of insulin receptor substrate 1 tyrosine 612 phosphorylation by IGF-1 was unaffected by ATM deficiency, though IGF-1 phosphatidylinositol 3-kinase activity tended to be lower in muscle from ATM haploinsufficient mice compared with wild-type muscle. The data suggest that ATM is a modulator of IGF-1 signalling downstream of insulin receptor substrate 1 in skeletal muscle.