Selenoprotein K (SELENOK) is primarily observed in the endoplasmic reticulum, and serves to maintain the normal physiological functions of skeletal muscle. Skeletal muscle development and regeneration are associated with significant changes in the expression of specific microRNAs (miRNAs). Downregulated SELENOK expression is observed in chicken muscles deficient of Se. However, the mechanisms of miRNA regulation of SELENOK expression remain elusive. Here, deep sequencing was used to detect the miRNA profiles of muscle in Se deficient (–Se group) and normal (C group) chickens. A dual-luciferase reporter assay was adopted to verify the relationship between SELENOK and gga-let-7f-3p. In addition, gga-let-7f-3p was either overexpressed or knocked-down in chicken myoblasts. Furthermore, the cells were treated with N-acetyl-L-cysteine (NAC) or hydrogen peroxide (H₂O₂) in order to probe the factors involved in oxidative stress, endoplasmic reticulum stress (ERS) and apoptosis, respectively. Relative to the C group, there were 132 differentially expressed miRNAs (including 57 upregulated and 75 downregulated) in the muscles of the –Se group. The dual-luciferase reporter assay showed that SELENOK was a primary target of gga-let-7f-3p. It was also observed that the overexpression or knock-down of gga-let-7f-3p significantly influenced the SELENOK expression. Moreover, NAC blocked mimics of ga-let-7f-3p, thus inducing oxidative stress, ERS and apoptosis. Simultaneously, gga-let-7f-3p inhibitors blocked the stimulant effects caused by H₂O₂ in chicken myoblasts. Furthermore, Se deficiency downregulated the SELENOK protein expression and induced oxidative stress, ERS and apoptosis in chicken muscles. In conclusion, the gga-let-7f-3p-SELENOK pathway played a pivotal role in Se deficiency mediated muscle injuries through the induction of oxidative stress and ERS, ultimately promoting apoptosis.

中文翻译：

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Gga-let-7f-3p通过靶向硒蛋白K †促进硒缺乏诱导的骨骼肌细胞凋亡

硒蛋白K（SELENOK）主要观察在内质网中，并用于维持骨骼肌的正常生理功能。骨骼肌的发育和再生与特定microRNA（miRNA）表达的显着变化有关。在缺乏Se的鸡肌肉中观察到SELENOK表达下调。但是，miRNA调控SELENOK表达的机制仍然难以捉摸。在这里，深度测序用于检测缺硒（–Se组）和正常（C组）鸡的肌肉的miRNA谱。采用双重荧光素酶报告基因测定来验证SELENOK和gga-let-7f-3p之间的关系。此外，gga-let-7f-3p在鸡成肌细胞中过表达或敲低。此外，用N处理细胞-乙酰基-L-半胱氨酸（NAC）或过氧化氢（H ₂ O ₂），以分别探测氧化应激，内质网应激（ERS）和细胞凋亡的相关因素。相对于C组，–Se组的肌肉中有132个差异表达的miRNA（包括57个上调和75个下调）。双重荧光素酶报告基因测定表明SELENOK是gga-let-7f-3p的主要靶标。还观察到，gga-let-7f-3p的过表达或敲除显着影响了SELENOK的表达。此外，NAC阻止了ga-let-7f-3p的模拟，从而诱导了氧化应激，ERS和细胞凋亡。同时，gga-let-7f-3p抑制剂阻断了H ₂ O引起的刺激作用₂在鸡成肌细胞中。此外，硒缺乏下调了SELENOK蛋白的表达，并诱导了鸡肌肉中的氧化应激，ERS和细胞凋亡。总之，gga-let-7f-3p-SELENOK途径通过诱导氧化应激和ERS在硒缺乏介导的肌肉损伤中发挥关键作用，最终促进细胞凋亡。