The effect of young and old ex vivo human serum on cellular protein synthesis and growth in an in vitro model of aging
The effect of young and old ex vivo human serum on cellular protein synthesis and growth in an in vitro model of aging
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DOI：
10.1152/ajpcell.00093.2021
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发表时间：
2021-07-01
影响因子：
5.5
通讯作者：
Breen, Leigh
中科院分区：
文献类型：
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作者：
Allen, Sophie L.;Marshall, Ryan N.;Breen, Leigh
肌肉衰老的体外模型有助于理解与年龄相关的肌肉损失的机制，并有助于开发靶向治疗。为了利用离体人血清在体外研究年龄相关肌肉损失的机制，从4名老年人（72 +/- 1岁）和4名年轻人（26 +/- 3岁）中获得空腹血液样本。与年轻参与者相比，老年人血浆CRP、IL-6、HOMA-IR水平升高，同心峰值扭矩和重复工作次数较低（P < 0.05）。C2C12肌管经血清和氨基酸饥饿1 h后，用人血清（10%）处理4 h或24 h。4 h后，C2C12细胞用5 mM亮氨酸处理30 min。通过表面翻译传感（SUnSET）技术检测肌肉蛋白合成（MPS），通过Western blot检测调节信号通路。与年轻供者相比，用老年血清处理的肌管直径显著减小（84%,P < 0.001）。与亮氨酸治疗前的年轻血清相比，老年供体血清组肌管MPS降低32%，P < 0.01)。年轻血清对肌管的MPS和Akt、p70S6K、eEF2的磷酸化反应均增加（P < 0.05），而老年血清对肌管的反应减弱（P < 0.05）。肌肉蛋白分解信号通路在两组之间没有差异。总之，我们发现，与年轻人相比，用老年人血清调节的肌管直径和MPS减少，这可能是由低度全身炎症驱动的。
In vitro models of muscle aging are useful for understanding mechanisms of age-related muscle loss and aiding the develop-ment of targeted therapies. To investigate mechanisms of age-related muscle loss in vitro utilizing ex vivo human serum, fasted blood samples were obtained from four old (72 +/- 1 yr) and four young (26 +/- 3 yr) men. Older individuals had elevated levels of plasma CRP, IL-6, HOMA-IR, and lower concentric peak torque and work-per-repetition compared with young participants (P < 0.05). C2C12 myotubes were serum and amino acid starved for 1 h and conditioned with human serum (10%) for 4 h or 24 h. After 4 h, C2C12 cells were treated with 5 mM leucine for 30 min. Muscle protein synthesis (MPS) was determined through the surface sensing of translation (SUnSET) technique and regulatory signaling pathways were measured via Western blot. Myotube diameter was significantly reduced in myotubes treated with serum from old, in comparison to young donors (84%, P < 0.001). MPS was reduced in myotubes treated with old donor serum, compared with young serum before leucine treatment (32%, P < 0.01). MPS and the phosphorylation of Akt, p70S6K, and eEF2 were increased in myotubes treated with young serum in response to leucine treatment, with a blunted response identified in cells treated with old serum (P < 0.05). Muscle protein breakdown signaling pathways did not differ between groups. In summary, we show that myotubes conditioned with serum from older individuals had decreased myotube diameter and MPS compared with younger individuals, potentially driven by low-grade systemic inflammation.