Mechanical unloading of 3D-engineered muscle leads to muscle atrophy by suppressing protein synthesis
Mechanical unloading of 3D-engineered muscle leads to muscle atrophy by suppressing protein synthesis
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3D 工程肌肉的机械卸载通过抑制蛋白质合成导致肌肉萎缩
DOI：
10.1152/japplphysiol.00323.2021
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发表时间：
2022
影响因子：
3.3
通讯作者：
Nakamura T
中科院分区：
文献类型：
--
作者：
Sugimoto T;Imai S;Yoshikawa M;Fujisato T;Hashimoto T;Nakamura T
三维（3D）工程肌肉是一个有用的方法，以更全面地了解的分子机制，卸载诱导的肌肉萎缩。我们研究了机械卸载对3D工程肌肉中与肌肉萎缩相关的分子肌肉蛋白合成（MPS）和肌肉蛋白分解（MPB）相关信号通路的影响，并更好地理解肌肉废用的体外模型。将由C2 C12成肌细胞和1型胶原凝胶组成的3D工程化肌肉分化2周，并分为3组：0天拉伸对照组（CON），2和/或7天拉伸组（ON），其中肌肉两端固定有人工肌腱，以及拉伸组（OFF），其中一侧人工肌腱分离。与ON组相比，OFF组的肌肉重量（−38.1%至−48.4%）、长度（−67.0%至−73.5%）、抽搐收缩力（−70.5%至−75.0%）和肌球蛋白重链表达（−32.5%至−50.5%）在第2天和第7天显著降低（P< 0.05，分别），尽管ON组随时间推移保持稳定。虽然无法确定决定性的分子信号传导，但在机械卸载后，由嘌呤霉素标记的蛋白质反映的MPS率显著降低（P< 0.05，-38.5%至51.1%）。同时，MPB，特别是泛素-蛋白酶体途径，没有受到影响。因此，体外3D工程肌肉的机械卸载通过抑制MPS、细胞分化和细胞生长而不是促进MPB而导致肌肉萎缩。新&值得注意的是，三维（3D）工程肌肉最近被证明可以紧密复制体内结构。我们发现，3D工程肌肉的机械卸载导致肌肉废用性萎缩，伴随着通过抑制肌肉蛋白质合成而降低的功能特性和收缩蛋白表达。这种新的模型可能会改善体外测试的方式，以减少机械卸载引起的萎缩的潜力。
Three-dimensional (3D)-engineered muscle is an useful approach to a more comprehensive understanding of molecular mechanisms underlying unloading-induced muscle atrophy. We investigated the effects of mechanical unloading on molecular muscle protein synthesis (MPS)- and muscle protein breakdown (MPB)-related signaling pathways involved in muscle atrophy in 3D-engineered muscle, and to better understand in vitro model of muscle disuse. The 3D-engineered muscle consisting of C2C12 myoblasts and type-1 collagen gel was allowed to differentiate for 2 wk and divided into three groups: 0 days of stretched-on control (CON), 2 and/or 7 days of stretched-on (ON), in which both ends of the muscle were fixed with artificial tendons, and the stretched-off group (OFF), in which one side of the artificial tendon was detached. Muscle weight (−38.1% to −48.4%), length (−67.0% to −73.5%), twitch contractile force (−70.5% to −75.0%), and myosin heavy chain expression (−32.5% to −50.5%) in the OFF group were significantly decreased ondays 2and7compared with the ON group (P< 0.05, respectively), despite that ON group was stable over time. Although determinative molecular signaling could not be identified, the MPS rate reflected by puromysin-labeled protein was significantly decreased following mechanical unloading (P< 0.05, −38.5% to −51.1%). Meanwhile, MPB, particularly the ubiquitin-proteasome pathway, was not impacted. Hence, mechanical unloading of 3D-engineered muscle in vitro leads to muscle atrophy by suppressing MPS, cell differentiation, and cell growth rather than the promotion of MPB.NEW & NOTEWORTHYThree-dimensional (3D)-engineered muscles have recently been shown to closely replicate the in vivo architecture. We found that mechanical unloading of 3D-engineered muscle led to muscle disuse atrophy accompanied by reduced functional properties and contractile protein expression via suppression of muscle protein synthesis. This novel model may improve the in vitro testing of modalities with the potential to reduce mechanical unloading-induced atrophy.