Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu 525-8577, Japan.
Division of Human Sciences, Faculty of Engineering, Osaka Institute of Technology, Ohmiya 535-8585, Japan.
Int J Mol Sci. 2022 May 20;23(10):5723. doi: 10.3390/ijms23105723.
Brain function-related myokines, such as lactate, irisin, and cathepsin B (CTSB), are upstream factors that control brain-derived neurotrophic factor (BDNF) expression and are secreted from skeletal muscle by exercise. However, whether irisin and CTSB are secreted by muscle contraction remains controversial. Three-dimensional (3D)-engineered muscle (3D-EM) may help determine whether skeletal muscle contraction leads to the secretion of irisin and CTSB, which has never been identified with the addition of drugs in conventional 2D muscle cell cultures. We aimed to investigate the effects of electrical pulse stimulation (EPS)-evoked muscle contraction on irisin and CTSB secretion in 3D-EM. The 3D-EM, which consisted of C2C12 myoblasts and type-1 collagen gel, was allowed to differentiate for 2 weeks and divided into the control and EPS groups. EPS was applied at 13 V, 66 Hz, and 2 msec for 3 h (on: 5 s/off: 5 s). Irisin and CTSB secretion into the culture medium was measured by Western blotting. Irisin secretion was significantly increased following EPS (p < 0.05). However, there was no significant difference in CTSB secretion between the two groups. The present study suggests that irisin may be a contractile muscle-derived myokine, but CTSB is not secreted by EPS-evoked muscle contractile stimulation in 3D-EM.
脑功能相关的肌因子，如乳酸、鸢尾素和组织蛋白酶 B（CTSB），是控制脑源性神经营养因子（BDNF）表达的上游因子，可通过运动从骨骼肌中分泌。然而，鸢尾素和 CTSB 是否通过肌肉收缩分泌仍存在争议。三维（3D）工程化肌肉（3D-EM）可能有助于确定肌肉收缩是否会导致鸢尾素和 CTSB 的分泌，这在常规 2D 肌肉细胞培养中加入药物的情况下从未得到证实。我们旨在研究电脉冲刺激（EPS）引起的肌肉收缩对 3D-EM 中鸢尾素和 CTSB 分泌的影响。由 C2C12 成肌细胞和 I 型胶原凝胶组成的 3D-EM 分化 2 周后，分为对照组和 EPS 组。EPS 以 13 V、66 Hz 和 2 msec 的参数施加 3 小时（通：5 s/断：5 s）。通过 Western blot 测定培养基中鸢尾素和 CTSB 的分泌。EPS 后鸢尾素分泌显著增加（p<0.05）。然而，两组之间 CTSB 分泌无显著差异。本研究表明，鸢尾素可能是一种收缩肌源性肌因子，但 CTSB 不是由 3D-EM 中 EPS 引起的肌肉收缩刺激分泌的。
