营养感知分子Ubxd8调控缢蛏HUFA合成的作用及机制研究

营养应答是生物体维持代谢平衡的重要手段。海洋软体动物可感知食物脂肪酸调控高不饱和脂肪酸（HUFA）合成，其HUFA营养应答机制有待阐明。Ubxd8通过感知体内HUFA水平介导激活Insig-1/SREBP-1通路调控HUFA合成，是哺乳动物HUFA营养应答的重要机制。我们前期发现海洋软体动物与哺乳动物的Ubxd8功能域高度保守，且Ubxd8与缢蛏HUFA合成关键基因表达关系密切。本项目拟在前期证实SREBP调控缢蛏HUFA合成基础上，借助等温滴定量热和双分子荧光互补等技术明确缢蛏Ubxd8对HUFA水平的感知功能；利用基因抑制/过表达、荧光定量PCR和气相色谱质谱等技术确认Ubxd8对缢蛏HUFA合成的调控作用；采用免疫印迹和免疫荧光等技术阐释Ubxd8调控缢蛏HUFA合成的分子途径。研究成果将为认识海洋软体动物营养感知的HUFA合成调控提供基础，为其饵料HUFA的精准选择提供指导和借鉴。

Nutrition response is a critical means for organisms to maintain metabolic balance. Marine molluscs can sense fatty acids in food to regulate the synthesis of highly unsaturated fatty acids (HUFA), the underlying HUFA nutrition response mechanism remains to be elucidated. Ubiquitin regulatory X domain containing protein 8 (Ubxd8) mediates the activation of Insig-1/SREBP-1 pathway to regulate HUFA synthesis by sensing the level of HUFA in vivo, which is an important mechanism of mammalian HUFA nutrition response. Previously, we found that the functional domains of Ubxd8 in marine molluscs and mammals are highly conserved, and the expression of Ubxd8 is closely related to that of key genes for HUFA synthesis in Sinonovacula constricta. Based on the previous demonstration that SREBP regulates HUFA synthesis in S. constricta, this project aims to clarify the sensing function of S. constricta Ubxd8 on HUFA level through technologies such as isothermal titration calorimetry and bimolecular fluorescence complementation; confirm the regulatory role of Ubxd8 in S. constricta HUFA synthesis by technologies such as gene suppression/overexpression, fluorescence quantitative PCR and gas chromatography-mass spectrometry; and elucidate the molecular pathway of Ubxd8 regulating HUFA synthesis in S. constricta using technologies such as immunoblotting and immunofluorescence. The results will provide a basis for understanding the regulation of HUFA synthesis in marine molluscs from the perspective of nutrition sensing, and provide guidance and reference for the precise selection for their dietary HUFA.