CD36偶联mTORC1调控外源长链脂肪酸吸收和利用的机制

All of 18 carbon atoms and longer long-chain fatty acids (LCFA) were required to uptake from blood for milk lipogenesis in bovine mammary epithelial cells, turn inward transport and esterification or desaturation to synthesize triglyceride and orther components of milk fat. CD36 is an exogenous LCFA membrane transporter, and it may play an important role in milk lipogenesis as a receptor of exogenous LCFA. It is realized that mTORC1 can regulate the synthesis of milk fat in various ways, but the relationship between CD36 and mTORC1 is not well known. This project aims to study the mechamism of CD36, FAK and mTORC1 forming the CD36/FAK/mTORC1 signaling pathway based on the results of the previous project which focus on the role of mTORC1 in milk lipogenesis. Here, we propose a new regulating model of LCFA signal transduction which related with synthesis of milk fat. Intended to be the role of molecular and cell biology as well as protomics techniques in relationship between CD36/FAK/mTORC1 pathway, transcription factors, and gene expresiion related with exogenous LCFA uptaking, turn inward transport, desaturation, synthesis of very long-chain fatty acids (VLCFAs) and triglyceride, and to discover the mechanism of products forming. The results obtained from this project will provide basic data and technical support to improve milk quality.

牛乳腺上皮细胞中乳脂合成所需18碳以上的长链脂肪酸全部由乳腺上皮细胞从血液中摄取，内转和利用其合成甘油三酯或其它乳脂成分。CD36是外源长链脂肪酸的膜转运器，但其作为受体促进乳脂合成的作用可能更为重要；mTORC1与乳脂合成密切相关，但CD36和mTORC1的关系目前并不清楚。我们在研究mTORC1在乳脂合成中的作用得到良好结果的基础上，力图通过本项目阐明CD36作为长链脂肪酸受体，通过FAK偶联mTORC1，构成CD36/FAK/mTORC1通路，提出新的与乳脂合成相关的长链脂肪酸信号转导模型。拟以硬脂酸（C18:0）作为外源刺激分子，通过分子细胞生物学技术和蛋白质组学技术阐明CD36/FAK/mTORC1通路、转录因子、外源长链脂肪酸吸收、去饱和、超长链脂肪酸和甘油三酯合成相关基因表达，以及产物形成之间的联系机制，为提高牛奶品质提供基础数据和技术支持。

奶牛乳腺上皮细胞中乳脂合成所需大约50%的C16和全部C18以上的长链脂肪酸主要由乳腺上皮细胞从血液中吸收、内转并利用其合成甘油三酯或其它乳脂成分。CD36是外源长链脂肪酸的膜转运器，但其作为膜受体促进乳脂合成的作用更为重要。mTORC1与乳脂合成密切相关，但CD36和mTORC1的关系目前并不清楚。项目以硬脂酸（C18:0）处理细胞，通过分子细胞生物学手段证明CD36作为硬脂酸的膜受体，通过Fyn激活FAK，级联 mTORC1，构成CD36/Fyn/FAK/mTORC1信号转导通路，进而激活转录因子PPARγ，调控外源长链脂肪酸吸收、去饱和、超长链脂肪酸和甘油三酯合成相关基因表达以及产物形成。此外，通过项目研究，对细胞内长链脂肪酸感受机制（胞内受体）有了初步认识，为确定软脂酸（C16:0）、硬脂酸（C18:0）和油酸（18:1）细胞内感受器提供了基础数据。总之，项目成果丰富了反刍动物营养学理论知识，为提高牛奶品质提供了理论基础和技术途径。项目执行期间，以项目为第一标注发表SCI收录论文4篇，国内核心期刊论文3篇。培养毕业博士研究生3名，硕士研究生6名。