DHA通过PPARγ-NIX/BNIP3信号轴介导的线粒体自噬调控草鱼脂肪细胞凋亡的机制分析

DHA具有促进脂肪细胞凋亡进而降低动物体脂蓄积的作用。申请人前期研究发现DHA在促进草鱼脂肪细胞凋亡的同时，上调线粒体自噬标志基因的表达。结合线粒体自噬促进细胞凋亡和PPARγ通过内源性途径介导DHA诱导草鱼前体脂肪细胞凋亡的报道，申请人推测线粒体不单在DHA诱导草鱼脂肪细胞凋亡过程中起到关键作用，且线粒体自噬可能通过内源性细胞凋亡途径参与了DHA的降脂过程。鉴于此，本申请项目拟采用草鱼原代脂肪细胞培养、免疫共沉淀等细胞分子生物学技术，结合在体饲喂，解析NIX/BNIP3介导的线粒体自噬在DHA促草鱼脂肪细胞凋亡过程中的作用，重点探究DHA作为信号分子，通过PPARγ-LC3-NIX/BNIP3信号轴激活Bax/Caspase9，进而诱导脂肪细胞凋亡的机理。研究结果有助于进一步阐明DHA降低草鱼脂质蓄积的分子调控机制，为完善淡水鱼类脂质蓄积调控理论及技术研发提供参考资料和研究思路。

DHA can promote the apoptosis of adipocytes and reduce the body fat in fish. Mitochondria are sensitive to nutrients and participate in cell apoptosis. Our laboratory found that DHA increased the expression of mitophagy marker genes, while promoting the apoptosis of grass carp adipocytes. Combined with the reports that mitophagy promotes apoptosis and PPARγ mediates DHA induced-apoptosis of grass carp preadipocytes through mitochondria-mediated apoptosis, we speculate that not only mitochondria are the determinants in the process of DHA induced-apoptosis of grass carp adipocytes, but also mitophagy may participate in DHA promoted-lipid reduction through mitochondria-mediated apoptosis. In this project, grass carp, the unique carp species in China, would be applied as the experimental animal, the molecular biological and cell biological techniques, including cell culture and co-immunoprecipitation as well as feeding experiment to explore the mechanism of mitophagy mediated by PPARγ- LC3-NIX/BNIP3 in DHA induced-apoptosis of grass carp adipocytes via activating Bax / caspase9. The results are helpful to elucidate the molecular regulation mechanism of DHA in reducing lipid accumulation in grass carp, and give a new theoretical foundation and research approach for the study of lipid metabolism in freshwater fish.