大菱鲆糖稳态的激素调控网络研究

Fish are born with diabetes. The mechanism is not fully clear. Turbot is one of the most important mariculture fish species in China. In our previous study, it was confirmed that it has the full capability of glycolysis and gluconeogenesis. The key enzymes in these two pathways are sensitive to the carbohydrate nutrition status of turbot. Based on the previous study, the present study is designed to clarify the glucose metabolism mechanism in respect to the hormone regulation in turbot. The methodologies and technologies of systematic biology (e.g., transcriptomics and metabolomics) and molecular biology (e.g., gene clone, RNAi, western blot) will be used. After a series of “in vitro” and “in vivo” studies on the levels of molecular, cell and individual, the hormones and their receptor involved in the regulation of the glucose metabolism will be screened, and their signaling pathway will be studied. The aim of the present study is to clarify the network of hormone regulating the glucose homeostasis in turbot. The expected results from the present study will provide the basic data for clarifying the mechanism of glucose metabolism and its regulation. At the same time, it also will provide the scientific supports for improving the ability of farmed fish to utilize dietary carbohydrate through the nutritional ways.

鱼类是天生的“糖尿病体质”，其利用糖的能力弱的机理还不完全清楚。本研究以我国重要的海水养殖鱼类——大菱鲆为对象，在我们先前已证明其体内有完整的糖酵解和糖异生代谢途径，并且其中关键酶的活性和基因表达对机体糖营养水平敏感的基础上，从激素调控的角度出发，利用先进的转录组和代谢组等系统生物学研究手段，以及基因克隆、基因干扰重建和western杂交等分子生物学研究技术，结合“离体”和“在体”研究方法，从分子、细胞和个体研究水平确定大菱鲆体内参与调控糖代谢的激素及其受体，研究其作用的信号通路，阐明大菱鲆体内糖稳态的激素调控网络。为进一步阐明鱼类糖代谢及其调控机制的理论问题提供基础数据，同时为通过营养途径提高养殖鱼类利用糖类物质的能力提供科学依据。

本研究以我国重要的海水养殖鱼类——大菱鲆为研究对象，并根据研究的需要，把牙鲆扩充到了本研究中，为将本研究成果延伸到肉食性海洋冷水性鱼类提供了更为完善的基础数据。确定了胰岛素介导的磷脂酰肌醇3激酶/蛋白激酶 B （PI3K/AKT）信号通路是调控糖代谢的主要途径。高糖负荷造成鱼体氧化胁迫并产生炎症反应，但并不通过氨基末端激酶JNK1，而是细胞因子信号转导抑制蛋白SOCS3途径抑制PI3K/AKT信号通路，进而调控葡萄糖的利用；体内游离脂肪酸特别是饱和脂肪酸通过抑制PI3K/AKT通路，引起体内胰岛素抵抗，进而抑制葡萄糖转运和糖酵解；确定鱼体内存在脑-肠轴，并首次证实通过脑-肠轴中的神经肽Y（NPY）和脑垂体腺甘酸环化酶激活化肽（PACAP）等关键因子影响胰岛素分泌水平和活性，从而调节糖转运、糖酵解和糖异生等途径，维持体内糖稳态，缓解高糖胁迫；CREB与PGC-1α参与胰高血糖素调控糖异生的信号通路，通路基因的上下游关系为PKA–CREB–PGC-1α–G6PC/PCK1/2；牙鲆原代肝细胞FoxO1敲降或饲料高糖引起的FoxO1被抑制，虽导致糖异生途径的cPEPCK和（或）G6pase1受到抑制，并且G6pase2被激活，而同时糖酵解途径的GK没被增强，因此不能有效降低高糖饲料引起的高血糖。. 以上研究已发表SCI论文11篇。