膜联蛋白A2（Annexin A2，AnxA2）是膜结合蛋白，其N端包含磷酸化位点和水解酶作用位点，具有调控细胞增殖、物质转运、代谢等功能，但其作用机理和信号途径尚待深入研究。本课题组前期发现AnxA2有36 kD和33 kD两种分子形式，且能介导氨基酸信号促进牛乳腺上皮细胞（BMEC）的增殖和乳蛋白合成。本研究拟利用过表达和siRNA确定AnxA2对细胞增殖和乳蛋白合成信号途径的影响；利用点突变和亚细胞定位确定AnxA2的磷酸化和水解位点及两种分子形式的亚细胞定位变化；利用siRNA、Co-IP和激酶抑制剂确定PLA2、PI3K和/或CDC42/Rac1对AnxA2调节功能的介导作用；利用GPCRs、PKCα、MMP9和MMP10的siRNA确定氨基酸活化AnxA2的信号通路。本工作将揭示AnxA2介导氨基酸促进BMEC增殖和乳蛋白合成的信号途径和分子机制。

Annexin A2 (AnxA2), a membrane binding protein, contains phosphorylation sites and proteolysis sites in its N terminal, which has been shown to play multiple biological roles in proliferation, transportation and metabolism. However, the regulatory mechanism and signaling pathway of AnxA2 still needst to be further characterized. Our research group previously found that AnxA2, exhibiting two molecular forms of 36 kD and 33 kD, could mediate the signal of amino acids and affect cell proliferation and milk protein synthesis of bovine mammary epithelial cell (BMEC). In this research, we firstly verify the effects on cellular signal transduction pathways to cell proliferation and milk protein sythesis. Site mutation and subcellular localization are used to analyze the phosphorylation sites, proteolysis sites and the migration of the two forms of AnxA2. siRNA, Co-IP and PI3K inhibitor are used to determine AnxA2 regulating downstream signaling pathway mediated by PI3K. And siRNA of GPCRs, PKCα, MMP9 and MMP10 are used to confirm the roles of these moleculars in the activation of AnxA2 by amino acids. Taken together, the aim of this project is to elucidate molecular mechanism of AnxA2 mediating amino acids signal and modulating signaling pathway related to cell proliferation and milk protein synthesis.