白念珠菌凋亡相关新基因IPF4847的功能研究

项目名称： 白念珠菌凋亡相关新基因IPF4847的功能研究

项目编号： No.30870105

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 医药、卫生

项目作者： 曹颖瑛

作者单位： 中国人民解放军第二军医大学

项目金额： 30万元

中文摘要： 近年来，以白念珠菌为主的深部真菌感染日益严重，对艾滋病，肿瘤，器官移植等病人构成严重危害。本课题针对前期发现的白念珠菌凋亡相关新基因IPF4847，采用基因敲除及高表达的方法研究其功能。结果表明，IPF4847是第一个发现的编码白念珠菌metacaspase基因，命名为CaMCA1。与野生型菌相比，CaMCA1基因缺失型白念珠菌对过氧化氢(H2O2)的抗性增强，细胞凋亡率和caspase活性明显下降，细胞内ROS产生减少，线粒体呼吸功能减弱，表现为ATP浓度及线粒体膜电位下降。进一步地，我们研究发现，经H2O2处理后白念珠菌细胞内Ca2+水平明显上升，伴随caspase活性升高。Ca2+信号通路中的关键基因cmp1和 crz1缺失菌在受到H2O2作用时，其细胞凋亡率明显低于野生型菌，伴随caspase活性下降，当将CaMCA1基因重新导入cmp1和 crz1基因缺失菌后，其细胞凋亡率及caspase活性上升恢复至野生型菌水平，表明CaMCA1位于白念珠菌Ca2+信号通路的下游介导细胞凋亡。另一方面，CaMCA1参与介导黄芩素协同两性霉素B诱导的白念珠菌细胞凋亡。

中文关键词： 白念珠菌；CaMCA1；凋亡；Ca2+；caspase

英文摘要： In recent years, more and more facts have proved that Candida albicans infection and drug resistance is very hazardous to the increased patients with immune function damaged. IPF4847 is a new C. albicans apoptosis-associated gene found in our early research. In this study, we investigated the function of IPF4847 thruogh gene deletion and overexpression. Our results showed that IPF4847 is the first metacapase found in C. albicans and named CaMCA1. Compared with wild-type C. albicans, camca1 mutant was more resistance to H2O2 treatment,showing lower apoptosis rate and caspase activity. Also, lower intracellular ATP concentration, lower mitochondrial membrane potential and less endogenous reactive oxygen species (ROS) generation were observed in camca1 mutant. Furthermore, we found that the intracellular Ca2+ level and caspase activity were increased in C. albicans upon H2O2 treatment.Both calcineurin (cmp1) and the calcineurin dependent transcription factor crz1 mutants showed decreased apoptosis and caspase activity upon H2O2 treatment compared to the wild-type cells. Expression of CaMCA1 in cmp1-deleted or crz1-deleted cells restored the cell sensitivity and caspase activity to H2O2. Our results suggest that Ca2+ and its downstream calcineurin/Crz1p/CaMCA1 pathway are involved in H2O2 -induced C. albicans apoptosis.On the other hand, CaMCA1 was found to mediated C. albicans apoptosis induced by the combinated treatment of baicalein and amphotericin B.

英文关键词： Candida albicans; CaMCA1; apoptosis; Ca2+；caspase