Shi Hua-Juan, Liu Wen-Bin, Xu Chao, Zhang Ding-Dong, Wang Bing-Ke, Zhang Li, Li Xiang-Fei
Key Laboratory of Aquatic Nutrition and Feed Science of Jiangsu Province, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, China.
Front Physiol. 2018 Apr 24;9:434. doi: 10.3389/fphys.2018.00434. eCollection 2018.
The RNA-binding protein quaking-a (Qkia) was cloned from the liver of blunt snout bream through the rapid amplification of cDNA ends method, with its potential role in glucose metabolism investigated. The full-length cDNA of covered 1,718 bp, with an open reading frame of 1,572 bp, which encodes 383 AA. Sequence alignment and phylogenetic analysis revealed a high degree of conservation (97-99%) among most fish and other higher vertebrates. The mRNA of was detected in all examined organs/tissues. Then, the plasma glucose levels and tissue expressions were determined in fish intraperitoneally injected with glucose [1.67 g per kg body weight (BW)], insulin (0.052 mg/kg BW), and glucagon (0.075 mg/kg BW) respectively, as well as in fish fed two dietary carbohydrate levels (31 and 41%) for 12 weeks. Glucose administration induced a remarkable increase of plasma glucose with the highest value being recorded at 1 h. Thereafter, it reduced to the basal value. After glucose administration, expressions significantly decreased with the lowest value being recorded at 1 h in liver and muscle and 8 h in brain, respectively. Then they gradually returned to the basal value. The insulin injection induced a significant decrease of plasma glucose with the lowest value being recorded at 1 h, whereas the opposite was true after glucagon load (the highest value was gained at 4 h). Subsequently, glucose levels gradually returned to the basal value. After insulin administration, the expressions significantly decreased with the lowest value being attained at 2 h in brain and muscle and 1 h in liver, respectively. However, glucagon significantly stimulated the expressions of in tissues with the highest value being gained at 6 h. Moreover, high dietary carbohydrate levels remarkably increased plasma glucose levels, but down-regulated the transcriptions of in tissues. These results indicated that the gene of blunt snout bream shared a high similarity with that of the other vertebrates. Glucose and insulin administration, as well as high-carbohydrate feeding, remarkably down-regulated its transcriptions in brain, muscle and liver, whereas the opposite was true after the glucagon load.
通过cDNA末端快速扩增法从团头鲂肝脏中克隆出RNA结合蛋白震颤蛋白-a（Qkia），并对其在葡萄糖代谢中的潜在作用进行了研究。其全长cDNA为1718bp，开放阅读框为1572bp，编码383个氨基酸。序列比对和系统发育分析表明，大多数鱼类和其他高等脊椎动物之间具有高度保守性（97-99%）。在所检测的所有器官/组织中均检测到了该蛋白的mRNA。然后，分别测定了腹腔注射葡萄糖[1.67g/kg体重（BW）]、胰岛素（0.052mg/kg BW）和胰高血糖素（0.075mg/kg BW）的鱼，以及喂食两种碳水化合物水平（31%和41%）12周的鱼的血浆葡萄糖水平和组织中该蛋白的表达。注射葡萄糖后血浆葡萄糖显著升高，1h时达到最高值，此后降至基础值。注射葡萄糖后，肝脏和肌肉中该蛋白的表达在1h时显著降低，大脑中在8h时显著降低，然后逐渐恢复到基础值。注射胰岛素后血浆葡萄糖显著降低，1h时达到最低值，而注射胰高血糖素后则相反（4h时达到最高值），随后葡萄糖水平逐渐恢复到基础值。注射胰岛素后，大脑和肌肉中该蛋白的表达在2h时显著降低，肝脏中在1h时显著降低。然而，胰高血糖素显著刺激了组织中该蛋白的表达，6h时达到最高值。此外，高碳水化合物饮食显著提高了血浆葡萄糖水平，但下调了组织中该蛋白的转录。这些结果表明，团头鲂的该基因与其他脊椎动物的基因具有高度相似性。葡萄糖和胰岛素给药以及高碳水化合物喂养显著下调了其在大脑、肌肉和肝脏中的转录，而注射胰高血糖素后则相反。
