Limb immobilization results in a rapid loss of muscle size and strength. The resultant alterations in signaling pathways governing myogenesis, catabolism, and mitochondrial biogenesis are likely to include posttranscriptional regulation mediated by altered microRNAs (miRNAs). Given that protein ingestion exerts an anabolic action and may act as a countermeasure to mitigate muscle loss with immobilization, it is important to examine miRNA in this context. The objective of the study is therefore to characterize the vastus lateralis miRNA response to 14 days of disuse in males (45–60 years) randomized to receive supplementation with 20 g d⁻¹ of dairy protein (n = 12) or isocaloric carbohydrate placebo (n = 13). Biopsies are collected before and after a 2‐week immobilization period. Of the 24 miRNAs previously identified in myogenic regulation, seven (miR‐133a, −206, −15a, −451a, −126, −208b, and let‐7e) are increased with immobilization irrespective of group; five (miR‐16, −494, let‐7a, −7c, and 7d) increased only in the carbohydrate group; and eight (miR‐1, −486, −23a, −23b, −26a, −148b, let‐7b, and −7g) are divergently expressed between groups (suppressed with protein). The ability of protein supplementation to differentially regulate miRNAs involved in key muscle regulatory pathways following short‐term limb immobilization reflects potential protective function in mitigating muscle loss during limb immobilization.

中文翻译：

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乳蛋白补充调节人类骨骼肌microRNA对下肢固定化的反应。

肢体固定会导致肌肉尺寸和强度的快速损失。在控制肌发生，分解代谢和线粒体生物发生的信号传导途径中产生的改变可能包括由改变的microRNA（miRNA）介导的转录后调控。鉴于蛋白质的摄入发挥了合成代谢的作用，并且可以作为通过固定减轻肌肉损失的对策，因此在这种情况下检查miRNA非常重要。因此，该研究的目的是表征男性（45-60岁）停用后14天的股外侧肌miRNA反应，随机接受补充20 g d ^-1的乳蛋白（n = 12）或等热量的碳水化合物安慰剂（n= 13）。在2周固定期之前和之后进行活检。先前在成肌调节中鉴定的24种miRNA中，有7种（miR-133a，-206，-15a，-451a，-126，-208b和let-7e）随固定而增加，而与组无关。仅在碳水化合物组中增加了五个（miR-16，-494，let-7a，-7c和7d）；八种（miR-1，-486，-23a，-23b，-26a，-148b，let-7b和-7g）在各组之间表达差异（被蛋白质抑制）。短期肢体固定后，蛋白质补充剂差异调节参与关键肌肉调节途径的miRNA的能力反映了在肢体固定期间减轻肌肉损失的潜在保护功能。