Department of Engineering Science, Bioscience and Technology Program, University of Electro-Communications, Chofu, Japan.
Research Fellowship for Young Scientists, Japan Society for the Promotion of Science, Chiyoda, Japan.
J Appl Physiol (1985). 2024 Sep 1;137(3):778-788. doi: 10.1152/japplphysiol.00335.2024. Epub 2024 Jul 25.
Hydrogen peroxide (HO) is one of the key signaling factors regulating skeletal muscle adaptation to muscle contractions. Eccentric (ECC) and concentric (CONC) contractions drive different muscle adaptations with ECC resulting in greater changes. The present investigation tested the hypothesis that ECC produces higher cytosolic and mitochondrial HO concentrations [HO] and alters gene expression more than CONC. Cytosolic and mitochondrial HO-sensitive fluorescent proteins, HyPer7 and MLS-HyPer7, were expressed in the anterior tibialis muscle of C57BL6J male mice. Before and for 60 min after either CONC or ECC (100 Hz, 50 contractions), [HO] and [HO] were measured by in vivo fluorescence microscopy. RNA sequencing was performed in control (noncontracted), CONC, and ECC muscles to identify genes impacted by the contractions. [HO] immediately after ECC was greater than after CONC (CONC: +6%, ECC: +11% vs. rest, < 0.05) and remained higher for at least 60 min into recovery. In contrast, the elevation of [HO] was independent of the contraction modes (time; < 0.0042, contraction mode; = 0.4965). The impact of ECC on [HO] was abolished by NADPH oxidase 2 (Nox2) inhibition (GSK2795039). Differentially expressed genes were not present after CONC or ECC + GSK but were found after ECC and were enriched for vascular development and apoptosis-related genes, among others. In conclusion, in mouse anterior tibialis, ECC, but not CONC, evokes a pronounced cytosolic HO response, caused by Nox2, that is mechanistically linked to gene expression modifications. This in vivo model successfully characterized the effects of eccentric (ECC) and concentric (CONC) contractions on cytosolic and mitochondrial [HO] in mouse skeletal muscle. Compared with CONC, ECC induced higher and more sustained [HO]-an effect that was abolished by Nox2 inhibition. ECC-induced [HO] elevations were requisite for altered gene expression.
过氧化氢 (HO) 是调节骨骼肌适应肌肉收缩的关键信号因子之一。离心 (ECC) 和向心 (CONC) 收缩导致不同的肌肉适应，ECC 导致更大的变化。本研究检验了以下假设：ECC 产生更高的细胞质和线粒体 HO 浓度 [HO]，并比 CONC 更改变基因表达。在 C57BL6J 雄性小鼠的前胫骨肌中表达了细胞质和线粒体 HO 敏感荧光蛋白 HyPer7 和 MLS-HyPer7。在 CONC 或 ECC（100Hz，50 次收缩）之前和之后 60 分钟，通过体内荧光显微镜测量 [HO] 和 [HO]。在对照（未收缩）、CONC 和 ECC 肌肉中进行 RNA 测序，以鉴定受收缩影响的基因。ECC 后立即 [HO] 高于 CONC（CONC：+6%，ECC：+11% vs. 休息，<0.05），至少在恢复 60 分钟内仍保持较高水平。相比之下，[HO] 的升高与收缩模式无关（时间；<0.0042，收缩模式；=0.4965）。ECC 对 [HO] 的影响被 NADPH 氧化酶 2 (Nox2) 抑制（GSK2795039）所消除。CONC 或 ECC+GSK 后没有差异表达的基因，但在 ECC 后存在，并富集血管发育和凋亡相关基因等。总之，在小鼠前胫骨肌中，ECC 而非 CONC 引起明显的细胞质 HO 反应，由 Nox2 引起，与基因表达修饰在机制上相关。该体内模型成功地描述了离心 (ECC) 和向心 (CONC) 收缩对小鼠骨骼肌细胞质和线粒体 [HO] 的影响。与 CONC 相比，ECC 诱导更高和更持续的 [HO]-这种效应被 Nox2 抑制所消除。ECC 诱导的 [HO] 升高是改变基因表达所必需的。
