Hypoxia, occurring in several pathologies, has deleterious effects on skeletal muscle, in particular on protein homeostasis. Different induction methods of hypoxia are commonly used in cellular models to investigate the alterations of muscular function consecutive to hypoxic stress. However, a consensus is not clearly established concerning hypoxia induction methodology. Our aim was to compare oxygen deprivation with chemically induced hypoxia using cobalt chloride (CoCl₂) or desferrioxamine (DFO) on C2C12 myotubes which were either cultured in hypoxia chamber at an oxygen level of 4% or treated with CoCl₂ or DFO. For each method of hypoxia induction, we determined their impact on muscle cell morphology and on expression or activation status of key signaling proteins of synthesis and degradation pathways. The expression of HIF-1α increased whatever the method of hypoxia induction. Myotube diameter and protein content decreased exclusively for C2C12 myotubes submitted to physiological hypoxia (4% O₂) or treated with CoCl₂. Results were correlated with a hypophosphorylation of key proteins regulated synthesis pathway (Akt, GSK3-β and P70S6K). Similarly, the phosphorylation of FoxO1 decreased and the autophagy-related LC3-II was overexpressed with 4% O₂ and CoCl₂ conditions. Our results demonstrated that in vitro oxygen deprivation and the use of mimetic agent such as CoCl₂, unlike DFO, induced similar responses on myotube morphology and atrophy/hypertrophy markers. Thus, physiological hypoxia or its artificial induction using CoCl₂ can be used to understand finely the molecular changes in skeletal muscle cells and to evaluate new therapeutics for hypoxia-related muscle disorders.

中文翻译：

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不同方法诱导细胞缺氧的影响：专注于蛋白质稳态信号传导途径和分化为肌管的C2C12骨骼肌细胞的形态。

发生在几种病理学中的缺氧对骨骼肌，特别是蛋白质稳态具有有害作用。细胞模型中通常使用不同的低氧诱导方法来研究低氧应激后肌肉功能的变化。但是，关于缺氧诱导方​​法尚无明确共识。我们的目的是在C2C12肌管上比较用氯化钴（CoCl ₂）或去铁胺（DFO）进行的化学剥夺性缺氧与缺氧在4％氧气水平下培养或用CoCl ₂处理的C2C12肌管。或DFO。对于每种缺氧诱导方​​法，我们确定了它们对肌肉细胞形态以及合成和降解途径的关键信号蛋白表达或激活状态的影响。无论缺氧诱导方​​法如何，HIF-1α的表达均增加。对于发生生理性缺氧（4％O ₂）或用CoCl ₂处理的C2C12肌管，肌管直径和蛋白质含量仅降低。结果与关键蛋白调节的合成途径（Akt，GSK3-β和P70S6K）的低磷酸化相关。同样，FoxO1的磷酸化降低，并且自噬相关的LC3-II在4％O ₂和CoCl _2中过表达条件。我们的研究结果表明，与DFO不同，体外除氧和模拟剂（如CoCl _2）的使用对肌管形态和萎缩/肥大标记物引起了相似的反应。因此，生理性缺氧或其使用CoCl _2的人工诱导可用于精细了解骨骼肌细胞的分子变化，并评估与缺氧相关的肌肉疾病的新疗法。