E3泛素连接酶Pallbearer介导凋亡细胞清除的分子机制研究

The prompt removal of apoptotic cells by phagocytes is one of the key step of programmed cell death.Defects in apoptotic cell clearance have been linked with various inflammatory diseases and autoimmune disease(such as systemic lupus erythematosus). Howerver, the detail mechanism of apoptotic cell clearance is still unclear. In order to further investigate the molecular mechanism of apoptotic cell clearance mediated by E3 ubiquitin ligase Pallbearer, we will use Drosophila melanogaster, an excellent model organism, to perform the following three parts of study: Study the cellular translocate of Pallbearer in macrophage mediated by apoptotic cells, the function of Pallbearer's cellular translocate in apoptotic cell clearance and the molecular mechanism of Pallbearer's cellular translocate; Determine the mechanism of how the expression level and activation of Small GTPase Rac2 were upregulated by degradation of phosphorylation RpS6, which was mediated by Pallbearer, Ubiquitin-Proteasome Pathway; Investigate what's the protein kinase that phosphorylate RpS6 during apoptotic cell clearance, which result in the directly binding of phosphorylation RpS6 with Pallbearer.In completion of this research project, we anticipate that our work will lead to the design of new strategies to fight autoimmune and infectious disease cause by defects in apoptotic cell clearance.

凋亡细胞被及时有效地清除是程序性细胞死亡的重要环节之一，其缺陷会导致严重慢性炎症和致死性自身免疫系统疾病(如系统性红斑狼疮)，但其调控机制目前还知之甚少。为了更深入地揭示E3泛素连接酶Pallbearer介导的凋亡细胞清除的分子机制，我们将借助黑腹果蝇这一优异的模式动物从以下三个方面进行研究：研究凋亡细胞介导的巨噬细胞中Pallbearer的细胞内转位，这种细胞内转位在凋亡细胞清除中的作用以及调控Pallbearer细胞内转位的分子机制；阐明Pallbearer介导的磷酸化RpS6通过泛素化-蛋白酶体途径降解所导致小G蛋白Rac2含量和活性上调的机制；探索凋亡细胞清除发生过程中是何种蛋白激酶磷酸化RpS6导致其和Pallbearer直接结合。此项课题的完成有助于我们揭示因凋亡细胞清除障碍而引发的严重炎症或致命性自身免疫系统疾病的分子基础。

凋亡细胞被及时而有效地清除是程序性细胞死亡的重要环节之一，其缺陷会导致严重慢性炎症和致死性自身免疫疾病(如系统性红斑狼疮)，但其调控机制目前还知之甚少。E3泛素连接酶Pallbearer介导凋亡细胞的清除，目前我们已证实：1）Pall蛋白N端两个亮氨酸作为出核信号在受到凋亡细胞诱导时介导Pall的细胞转位，且已经找到一个蛋白—Madm可特异性调控其出核过程；2）Pall介导了小G蛋白Rac2含量和活性的上调，研究发现Pall是通过自噬-溶酶体降解途径介导Rac2的含量，当Atg5和Atg3敲低抑制了自噬体及自噬小泡的形成，则会减缓Pall对Rac2蛋白的降解速率；3）凋亡细胞清除发生过程中激酶SNF1A和SNF4A磷酸化RpS6，导致其和Pallbearer直接结合。此项课题的完成有助于我们揭示因凋亡细胞清除障碍而引发的严重炎症或致命性自体免疫疾病的分子基础。