共轭亚油酸降低草鱼肝脏脂肪积累关键调控因子的筛选与鉴定

Nutrition-associated liver disease (NALD) is one of the bottleneck problems for a sustainable development of aquaculture. However, there is no known effective prophylaxis for NALD, and there is no effective treatment for most cases of NALD. It has been revealed that dietary conjugated linoleic acid (CLA) can effectively decrease liver lipid concentration in grass carp in our pre-experiment. The present study aims to clarify the key regulators for this lipid-lowering effects of CLA in grass carp. In the present study, an 8 weeks of feeding trial was conducted to identify the optimal dose of CLA for grass carp (CLAOPT), and the comparative transcriptome were conducted in livers of the CLAOPT and no CLA-supplemented groups to obtain the differentially expressed genes, and then the cellular function of these differentially expressed genes and their whole-body metabolic pathways were analyzed to obtain the key regulators in the transcriptional regulation networks. Moreover, qRT-PCR and immunohistochemistry will be used to identification those key regulators in their transcriptional and translational regulation and finally, to gain the key regulators for the fish. The present study will be essential for further elucidating the molecular mechanism and for effective prophylaxis and treatment of the NALD in grass carp, and for selective breeding of the highly sensitive fishes to dietary CLA, and it will help to gain a new insight for effective prophylaxis and treatment for most cases of NALD in aquaculture practice. On the other hand, it will provide a solid foundation for the development of CLA-supplemented diets and CLA-enriched aqua-food and for relieving the shortage of fish oil in aquaculture.

营养性脂肪肝是制约水产养殖业可持续发展的瓶颈问题，目前尚无有效的防治措施。在我们发现共轭亚油酸(CLA)可有效降低草鱼肝脏脂肪积累的基础上，本项目拟以草鱼为研究对象，通过生长实验，确定CLA降低其肝脏脂肪含量的适宜添加量(CLAOPT)，随后综合运用转录组测序、分子和免疫技术，系统地对CLA发挥降脂功效的关键调控因子展开研究。通过对CLAOPT组和未添加CLA组肝脏的比较转录组研究，经转录过程中差异表达基因的细胞学功能和机体代谢调控网络分析，筛选出关键调控因子；继而通过mRNA和蛋白表达量的双重鉴定得到若干关键调控因子，为阐明CLA发挥降脂功效的分子机理奠定研究基础。本项目的实施将会为通过CLA营养调控防治草鱼营养性脂肪肝并选育CLA降脂作用敏感基因型鱼类奠定理论基础，拓宽鱼类营养性脂肪肝防治的研究视角，并为开发CLA类饲料添加剂和保健水产品以及缓解现阶段紧张的饲用鱼油资源提供理论依据。

营养性脂肪肝是制约水产养殖业可持续发展的瓶颈，其防治措施尚不多见。本研究首先采用生长实验和组织显微和超微病理观察，分别确定饲料中2% (CLAopt)和1% (CLAopt) 的CLA在不影响草鱼或瓦氏黄颡鱼生长和鱼体健康的前提下，可显著降低其肝脂积累。随后综合运用转录组测序、GO和KEGG分析，系统地对CLA发挥降脂功效的关键调控因子展开研究。研究结果如下：在草鱼中，共获得973个差异表达基因，上述DEGs可显著富集到脂肪细胞因子信号通路、固醇生物合成、脂肪酸延长、脂肪酸分解、亚油酸代谢、PPARα信号和胰岛素信号通路等信号通路，其中筛选出与脂肪代谢通路相关基因/转录调控因子共34个。在瓦氏黄颡鱼中，共获得512个差异表达基因，其中这些差异表达基因可显著富集到脂肪酸代谢通路、胰岛素信号通路、脂肪细胞因子信号通路、PPARα信号通路和胆汁分泌信号通路等，其中与脂肪代谢通路相关基因/转录因子共19个。经转录水平和蛋白水平双重鉴定，在草鱼中鉴定到CLA降低其肝脂积累的关键调控因子为：PPARα、PPARγ、LPL和CPT1；在瓦氏黄颡鱼中鉴定到的关键调控因子为：FAS、PPARα和TGL。上述研究结果为通过CLA营养调控防治草鱼/瓦氏黄颡鱼营养性脂肪肝并选育CLA降脂作用敏感基因型鱼类奠定理论基础，拓宽鱼类营养性脂肪肝防治的研究视角。