IGFBPs play a pivotal role in regulating the physiological function of IGFs (insulin-like growth factors). As an important member of IGFBPs, IGFBP3 is involved in the regulation of physiological functions of IGFs. To investigate the functional role of Igfbp3 in a herbivorous fish species, grass carp igfbp3 (GenBank accession no. MN251843) was isolated from the liver by molecular cloning. The ORF of grass carp igfbp3 was 882 bp, which encoded 293 amino acids, and the first 22 amino acids comprised the signal peptide. The predicted molecular weight of grass carp Igfbp3 is 31.95 kDa, and the theoretical isoelectric point is 8.32. Grass carp Igfbp3 displayed a high identity with its counterparts of common carp and zebrafish. And phylogenetic tree analysis showed that the grass carp Igfbp3 was clustered into the Igfbp3 subgroups of common carp and zebrafish. Tissue distribution study showed that igfbp3 was ubiquitously expressed in all tissues examined in the present study. High expression level of igfbp3 was detected in the heart, brain and fat of grass carp. The OGTT demonstrated that igfbp3 mRNA expression was significantly elevated in the liver of grass carp in response to glucose treatment. In vitro study showed that insulin could markedly stimulated igfbp3 mRNA expression in primary grass carp hepatocytes. Moreover, igfbp3 mRNA levels were also regulated by glucagon in grass carp primary hepatocytes. These results may provide the theoretical foundation for investigating the role of Igfbp3 in fish metabolism.

中文翻译：

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草鱼中的Igfbp3：在葡萄糖，胰岛素和胰高血糖素下的分子鉴定和mRNA表达。

IGFBPs在调节IGFs（胰岛素样生长因子）的生理功能中起关键作用。作为IGFBPs的重要成员，IGFBP3参与了IGFs生理功能的调节。为了研究Igfbp3在草食性鱼类中的功能作用，通过分子克隆从肝脏分离出草鱼igfbp3（GenBank登录号MN251843）。草鱼igfbp3的ORF为882 bp，编码293个氨基酸，前22个氨基酸组成信号肽。草鱼Igfbp3的预测分子量为31.95 kDa，理论等电点为8.32。草鱼Igfbp3与普通鲤鱼和斑马鱼的对应物具有很高的同一性。系统进化树分析表明，草鱼Igfbp3聚集在鲤鱼和斑马鱼的Igfbp3亚组中。组织分布研究表明，igfbp3在本研究检查的所有组织中普遍存在。在草鱼的心脏，大脑和脂肪中检测到igfbp3的高表达水平。OGTT证实，响应葡萄糖处理，草鱼肝脏中igfbp3 mRNA表达显着升高。体外研究表明，胰岛素可以显着刺激原代草鱼肝细胞中igfbp3 mRNA的表达。此外，草鱼原代肝细胞中的胰高血糖素也调节igfbp3 mRNA的水平。这些结果可为研究Igfbp3在鱼类代谢中的作用提供理论依据。组织分布研究表明，igfbp3在本研究检查的所有组织中普遍存在。在草鱼的心脏，大脑和脂肪中检测到igfbp3的高表达水平。OGTT证实，响应葡萄糖处理，草鱼肝脏中igfbp3 mRNA表达显着升高。体外研究表明，胰岛素可以显着刺激原代草鱼肝细胞中igfbp3 mRNA的表达。此外，草鱼原代肝细胞中的胰高血糖素也调节igfbp3 mRNA的水平。这些结果可为研究Igfbp3在鱼类代谢中的作用提供理论依据。组织分布研究表明，igfbp3在本研究检查的所有组织中普遍存在。在草鱼的心脏，大脑和脂肪中检测到igfbp3的高表达水平。OGTT证实，响应葡萄糖处理，草鱼肝脏中igfbp3 mRNA表达显着升高。体外研究表明，胰岛素可以显着刺激原代草鱼肝细胞中igfbp3 mRNA的表达。此外，草鱼原代肝细胞中的胰高血糖素也调节igfbp3 mRNA的水平。这些结果可为研究Igfbp3在鱼类代谢中的作用提供理论依据。OGTT证实，响应葡萄糖处理，草鱼肝脏中igfbp3 mRNA表达显着升高。体外研究表明，胰岛素可以显着刺激原代草鱼肝细胞中igfbp3 mRNA的表达。此外，草鱼原代肝细胞中的胰高血糖素也调节igfbp3 mRNA的水平。这些结果可为研究Igfbp3在鱼类代谢中的作用提供理论依据。OGTT证实，响应葡萄糖处理，草鱼肝脏中igfbp3 mRNA表达显着升高。体外研究表明，胰岛素可以显着刺激原代草鱼肝细胞中igfbp3 mRNA的表达。此外，草鱼原代肝细胞中的胰高血糖素也调节igfbp3 mRNA的水平。这些结果可为研究Igfbp3在鱼类代谢中的作用提供理论依据。