Yu Shengchen, Wang Jianfang, Liu Haibing, Guo Juntao, Kuraz Abebe Belete, Pan Yueting, Li Anning, Mei Chugang, Cheng Gong, Zan Linsen
College of Animal Science and Technology, Northwest A&F University, Yangling, China.
College of Grassland Agriculture, Northwest A&F University, Yangling, China.
J Cachexia Sarcopenia Muscle. 2025 Aug;16(4):e70009. doi: 10.1002/jcsm.70009.
Intramuscular fat (IMF) is a key determinant of meat quality. Excessive IMF deposition, commonly observed in human obesity and aging, negatively affects skeletal muscle function. Circular RNAs (circRNAs) play critical regulatory roles in muscle and fat development, as well as in the progression of related diseases. However, the specific functions and underlying mechanisms of circRNAs in IMF deposition have not been extensively studied.
We screened adipogenic differentiation-related circRNAs using circRNA-seq combined with WGCNA. Functional analyses, including loss-of-function and gain-of-function experiments, were performed to determine the role of circGLIS3 in regulating adipogenesis in bovine intramuscular preadipocytes and 3T3-L1 cells. A high-fat diet-induced mouse model was established to investigate the in vivo effects of circGLIS3 on skeletal muscle fat infiltration in mice (C57BL/6; n = 6 males). Mechanistic studies involved transcriptomic analysis, dual-luciferase reporter assays, RNA immunoprecipitation, and rescue experiments.
We screened and characterized a novel circRNA, circGLIS3, which is highly expressed in bovine IMF tissue and in the skeletal muscle of mice exhibiting fat infiltration. Functionally, circGLIS3 overexpression inhibited triglyceride synthesis (-16.19%, p < 0.01) and lipid droplet accumulation (-42.44%, p < 0.01) in intramuscular preadipocytes, concurrently downregulating the expression of key adipogenesis-related genes and proteins (p < 0.05). CircGLIS3 knockdown promoted triglyceride synthesis (+28.32%, p < 0.05) and lipid droplet accumulation (+47.40%, p < 0.01) in intramuscular preadipocytes, accompanied by a significant upregulation of adipogenesis-related genes and proteins (p < 0.05). Notably, circGLIS3 exhibits more than 80% sequence homology among bovine, mouse, and human species. CircGLIS3 overexpression inhibited triglyceride synthesis (-28.84%, p < 0.01) and lipid droplet accumulation (-46.49%, p < 0.01) in 3T3-L1 cells, concurrently downregulating the expression of adipogenesis-related genes and proteins (p < 0.05). Overexpression of circGLIS3 reduced skeletal muscle fat infiltration induced by high-fat diet in mice (-57.88%, p < 0.05). Mechanistically, circGLIS3 acts as a sponge for miR-21-3p, increasing the expression of its target gene, LEPR (+56.05%, p < 0.01), and promoting the phosphorylation level of its downstream signalling protein, AMPKα (+68.68%, p < 0.01).
CircGLIS3 inhibits bovine intramuscular adipogenesis by regulating the miR-21-3p/LEPR/AMPK axis, reducing fat infiltration in mouse skeletal muscle. These findings suggest that circGLIS3 is a promising target for improving meat quality in livestock, and as a potential therapeutic marker for alleviating skeletal muscle fat infiltration associated with obesity.
肌内脂肪（IMF）是肉质的关键决定因素。在人类肥胖和衰老过程中常见的IMF过度沉积会对骨骼肌功能产生负面影响。环状RNA（circRNAs）在肌肉和脂肪发育以及相关疾病进展中发挥关键调节作用。然而，circRNAs在IMF沉积中的具体功能和潜在机制尚未得到广泛研究。
我们使用circRNA测序结合WGCNA筛选了与脂肪生成分化相关的circRNAs。进行了包括功能丧失和功能获得实验在内的功能分析，以确定circGLIS3在调节牛肌内前脂肪细胞和3T3-L1细胞脂肪生成中的作用。建立了高脂饮食诱导的小鼠模型，以研究circGLIS3对小鼠（C57BL/6；n = 6只雄性）骨骼肌脂肪浸润的体内影响。机制研究包括转录组分析、双荧光素酶报告基因检测、RNA免疫沉淀和拯救实验。
我们筛选并鉴定了一种新型circRNA，circGLIS3，它在牛IMF组织和表现出脂肪浸润的小鼠骨骼肌中高度表达。在功能上，circGLIS3过表达抑制了肌内前脂肪细胞中甘油三酯的合成（-16.19%，p < 0.01）和脂滴积累（-42.44%，p < 0.01），同时下调了关键脂肪生成相关基因和蛋白质的表达（p < 0.05）。circGLIS3敲低促进了肌内前脂肪细胞中甘油三酯的合成（+28.32%，p < 0.05）和脂滴积累（+47.40%，p < 0.01），伴随着脂肪生成相关基因和蛋白质的显著上调（p < 0.05）。值得注意的是，circGLIS3在牛、小鼠和人类物种中表现出超过80%的序列同源性。circGLIS3过表达抑制了3T3-L1细胞中甘油三酯的合成（-28.84%，p < 0.01）和脂滴积累（-46.49%，p < 0.01），同时下调了脂肪生成相关基因和蛋白质的表达（p < 0.
