CIDEC基因调控奶牛乳腺乳脂合成的机理研究

乳脂是牛乳的主要成分之一，其含量是关系牛乳营养价值和风味的重要指标。本研究前期结果发现，CIDEC的表达与奶牛的乳脂率之间呈现正相关。奶牛乳腺上皮细胞中CIDEC基因过表达和干扰以后，甘油三酯的合成量发生相应地升高和降低，与甘油三酯合成相关的酶的表达也相应升高和降低。分离纯化奶牛乳腺上皮细胞的核蛋白，检测到CIDEC能够进入细胞核。以上结果表明CIDEC可以通过调节乳脂合成关键酶的表达来调控乳脂合成。为阐明其在乳脂合成调控中的作用方式，我们首先研究乳脂合成前体物对CIDEC表达及转位入核的影响；然后分析PI3K-JNK-PPARγ、mTOR和AMPK等信号通路对CIDEC表达的调控；最后研究CIDEC同C/EBP家族成员或免疫共沉淀技术筛选出的其他转录因子共同作用，调节乳脂合成关键酶表达的调控方式。本研究结果将会使我们更清楚地理解奶牛乳腺的泌乳过程，明确CIDEC调控乳脂合成的分子机制。

Milk fat is the major nutrition component in milk and accounts for many of the manufacturing characteristics and organoleptic qualities of milk and milk products. Preliminary study showed that the expression of CIDEC was positively correlated with milk fat content in lactation mammary glands of dairy cows. In cultured mammary epithelial cells, CIDEC knockdown decreased the content of triglycerides, as well as the expression of enzymes and regulatory factors involved in triglyceride synthesis, whereas overexpression of CIDEC had the opposite effects. We also found CIDEC was localized in the nucleus of mammary epithelial cells of dairy cows. All these results suggest that CIDEC has the role in increasing milk fat synthesis by regulating the expression of enzymes related to this process. So in this study, we plan to investigate the effect of acetate and β-hydroxybutyrate on the expression and nuclear accumulation of CIDEC, following by detecting the effect of PI3K-JNK-PPARγ, mTOR and AMPK signal pathways on CIDEC expression. To delineate the regulatory mechanism of CIDEC on the expression of enzymes involved in fat synthesis, coimmunoprecipitation and ChIP were used to detect how CIDEC interacts with C/EBP family members or other transcription factors to regulate the expression of genes encoding enzymes for the milk fat synthesis pathway in mammary gland of dairy cow. These results will help us understand the process of lactation and clarify the molecular mechanism of milk fat synthesis in dairy cows.