Autophagy is an important evolutionary conserved process in eukaryotic organisms for the turnover of intracellular substances. Recent studies revealed that autophagy displays circadian rhythms in mice and zebrafish. To date, there is no report focused on the rhythmic changes of autophagy in fish skeletal muscles upon nutritional deprivation. In this study, we examined the circadian rhythms of 158 functional genes in tilapia muscle in response to starvation. We found that 12 genes were involved in autophagy changed their rhythm after starvation. Among these genes, Atg4c, Bnip3la, Lc3a, Lc3b, Lc3c, and Ulk1a exhibited a daily rhythmicity in tilapia muscle, and Atg4b, becn1, bnip3la, bnip3lb, Lc3a, and ulk1b were significantly upregulated in response to starvation. The number of autophagosomes was dramatically increased in fasted fish, indicating that nutritional signals affect not only the muscular clock system but also its autophagy behavior. Administration of GSK4112, an activator of Nr1d1, altered rhythmic expression of both circadian clock genes and autophagy genes in tilapia muscle. Taken together, these findings provide evidence that nutritional deficiency affects both circadian regulation and autophagy activities in skeletal muscle.

中文翻译：

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Nr1d1通过调节自噬相关基因的节律性表达来影响尼罗罗非鱼幼体骨骼肌的自噬。

自噬是真核生物中细胞内物质更新的重要进化保守过程。最近的研究表明自噬在小鼠和斑马鱼中显示出昼夜节律。迄今为止，尚无关于营养剥夺后鱼类骨骼肌自噬节律性变化的报道。在这项研究中，我们检查了罗非鱼肌肉中158个功能基因对饥饿的昼夜节律。我们发现饥饿后参与自噬的12个基因改变了它们的节律。在这些基因中，Atg4c，Bnip3la，Lc3a，Lc3b，Lc3c和Ulk1a在罗非鱼的肌肉中表现出日常节律性，并且Atg4b，becn1，bnip3la，bnip3lb，Lc3a和ulk1b在饥饿时显着上调。禁食鱼中自噬体的数量急剧增加，表明营养信号不仅影响肌肉时钟系统，还影响其自噬行为。NSK1112的激活剂GSK4112的使用改变了罗非鱼肌肉中昼夜节律基因和自噬基因的节律性表达。综上所述，这些发现提供了营养缺乏会影响昼夜调节和骨骼肌自噬活动的证据。