College of Animal Science and Technology, Shandong Agricultural University, Taian, P. R. China.
Institute of Animal Immune Engineering, Jiangsu Academy of Agricultural Sciences, Nanjing, P. R. China.
FASEB J. 2022 Mar;36(3):e22206. doi: 10.1096/fj.202101723R.
Previous work demonstrated that arginine is one of the strongest insulin secretagogues. However, knowledge of the mechanisms linking chronic arginine metabolism with β-cell function and insulin secretion is relatively limited. After preliminary selection of concentration according to the cell proliferation, the MIN6 pancreatic β-cells were randomly assigned to culture in 0.04 mM (low-arginine, LA), 0.4 mM (standard-arginine, SA), or 8 mM arginine (high-arginine, HA) for 24 h. Following the treatment, a combination of transcriptomics and metabolomics, together with a series of molecular biological tests were performed to investigate the responses of β-cells to varied arginine availability. Our results showed that HA treatment reduced the chronic insulin releases, and LA and HA treatments decreased the glucose-stimulated insulin secretions (GSIS) of β-cells relative to the SA group (p < .05). Transcriptomics analysis indicated that LA administration significantly inhibited oxidative phosphorylation and ATP metabolic process but promoted DNA repair and mRNA processing in β-cells, while HA administration affected ammonium ion metabolic process and mRNA export (p < .05). Both LA and HA regulated the expressions of genes involved in DNA replication, cell-cycle phase transition, and response to oxidative stress (p < .05). Protein-protein interaction and transcription factor analyses suggested that Trp53 and Nr4a2 genes may play key roles during arginine stimulation. On the contrary, metabolomics analysis demonstrated that the differentially expressed metabolites (DEM) of MIN6 β-cells induced by LA were mainly enriched in glycerophospholipid metabolism, linoleic acid metabolism, and purine metabolism, while most DEMs between LA vs. SA comparison belonged to amino acid metabolism. When combined the three groups, co-expression analysis suggested that insulin secretions had strong associations with L-pyroglutamic acid, L-glutamate, and creatine concentrations, while intracellular insulin contents were mainly correlated to L-arginine, argininosuccinic acid, and phosphorylcholine. At last, integrated analysis of transcriptomics and metabolomics showed that glycerophospholipid metabolism, biosynthesis of unsaturated fatty acids, and amino acid metabolism were the most relevant pathways in β-cells exposed to abnormal arginine supply. This descriptive bioinformatics analysis suggested that the disturbed carbohydrate, lipid, and amino acid metabolisms, as well as the increased apoptosis and elevated oxidative stress, contributed to the reduced insulin secretion and lower GSIS in β-cells induced by LA or HA treatments, while some underlying mechanisms need to be further explored.
先前的研究表明，精氨酸是最强的胰岛素分泌激动剂之一。然而，关于慢性精氨酸代谢与β细胞功能和胰岛素分泌之间的联系的知识相对有限。根据细胞增殖初步选择浓度后，将 MIN6 胰岛β细胞随机分配到 0.04 mM（低精氨酸，LA）、0.4 mM（标准精氨酸，SA）或 8 mM 精氨酸（高精氨酸，HA）中培养 24 小时。处理后，采用转录组学和代谢组学相结合的方法，结合一系列分子生物学试验，研究β细胞对不同精氨酸供应的反应。我们的结果表明，HA 处理降低了慢性胰岛素释放，LA 和 HA 处理与 SA 组相比降低了葡萄糖刺激的胰岛素分泌（GSIS）（p <.05）。转录组学分析表明，LA 处理显著抑制了氧化磷酸化和 ATP 代谢过程，但促进了 β 细胞中的 DNA 修复和 mRNA 加工，而 HA 处理影响了氨离子代谢过程和 mRNA 输出（p <.05）。LA 和 HA 均调节了参与 DNA 复制、细胞周期相变和氧化应激反应的基因的表达（p <.05）。蛋白质-蛋白质相互作用和转录因子分析表明，Trp53 和 Nr4a2 基因在精氨酸刺激过程中可能发挥关键作用。相反，代谢组学分析表明，LA 诱导的 MIN6 β 细胞的差异表达代谢物（DEM）主要富集在甘油磷脂代谢、亚油酸代谢和嘌呤代谢中，而 LA 与 SA 比较之间的大多数 DEM 属于氨基酸代谢。当结合这三组时，共表达分析表明胰岛素分泌与 L-焦谷氨酸、L-谷氨酸和肌酸浓度具有很强的相关性，而细胞内胰岛素含量主要与 L-精氨酸、精氨酸琥珀酸和磷酸胆碱相关。最后，转录组学和代谢组学的综合分析表明，甘油磷脂代谢、不饱和脂肪酸的生物合成和氨基酸代谢是暴露于异常精氨酸供应的β细胞中最相关的途径。这种描述性的生物信息学分析表明，碳水化合物、脂质和氨基酸代谢的紊乱，以及细胞凋亡的增加和氧化应激的升高，导致 LA 或 HA 处理诱导的胰岛素分泌减少和 GSIS 降低，而一些潜在的机制需要进一步探索。
