Epac蛋白在肺上皮细胞应对烟曲霉侵染过程中的功能研究

Epac is a protein directly activated by cAMP (a key second messenger). It can regulate the phagocytosis of macrophages mediated by CR3 and interact with phospholipase D and phosphatidic acid signal closely. It plays an important role in host immune response and pulmonary diseases alone or with protein kinase A. Aspergillus fumigatus, an important pathogenic fungus of invasive pulmonary aspergilosis is able to internalize into pulmonary epithelial cells and induce inflammatory factors release; however the pathogenic mechanism of A. fumigatus is still unclear. We found that the internalization of A. fumigatus into pulmonary epithelial cells could be mediated by CR3 accompanied with PLD activation and the changes of PA and cAMP level in cells. Furthermore, A. fumigatus can inhibit the expression of Epac in pulmonary epithelial cells. Thus, we will investigate further the expression, translocation and activity of epac during A. fumigatus internalization into pulmonary epithelial cells and its function of regulating invasion and release of inflammation factors, and analyze the relationship of Epac with PLD and PA signaling pathway, and discuss the interaction of Epac and PKA signal during A.fumigatus internalization. This proposal would help clarify the mechanism of A.fumigatus internalization into pulmonary epithelial cell and the function of Epac and also greatly facilitate the development of antifungal drugs.

Epac蛋白是宿主细胞内重要第二信使分子cAMP的下游直接效应蛋白，可参与调控补体受体3介导的巨噬细胞吞噬且与细胞内重要信号分子磷脂酶D和磷脂酸关系密切，能单独或与蛋白激酶A一起在宿主天然免疫应答和肺部疾病中发挥重要作用。引发侵袭性肺曲霉病的主要病原真菌烟曲霉可内化侵入肺上皮细胞，诱导炎症因子释放，该过程的具体调控机制仍未阐明。我们研究发现，肺上皮细胞应对烟曲霉侵染过程可受补体受体3调控并伴有磷脂酶D活性、磷脂酸和cAMP含量改变，且胞内Epac蛋白表达受抑制。因此，本项目拟系统研究烟曲霉侵染过程中肺上皮细胞Epac蛋白表达、定位和活性变化规律及其对内化侵入和炎症因子释放的调控作用，解析Epac蛋白与磷脂酶D和磷脂酸的相互关系，并探讨其与蛋白激酶A在侵染过程中的交互效应。这将有助于阐明烟曲霉侵染肺上皮细胞的分子机制和Epac蛋白的调控功能，为寻找新的抗真菌药物靶点提供重要科学依据。