环状RNA（circRNAs）是真核细胞中发现的首尾共价连接的单链RNA分子，具有调节目的基因表达、编码蛋白等功能。新型隐球酵母中发现了73条circRNAs，其功能尚未鉴定。其中circCNYPT5产生于Rab5 GTPase编码基因YPT5，该基因在胞吞和液泡融合过程中起重要作用，在隐球菌中的功能也未鉴定。本课题以circCNYPT5和其宿主基因YPT5为主要研究对象，利用建立的CRISPR-Cas9编辑系统构建circRNA缺陷突变、编辑宿主基因YPT5、过表达circCNYPT5等，以推算circCNYPT5和YPT5的功能、之间表达的相关性，对YPT5可变转录本生产的影响，对致病性的影响等。采用qRT-PCR检测所有的73条circRNAs的表达以获得规律信息，为进一步开展隐球菌circRNA研究奠定基础，为circRNA生物学研究贡献知识。

CircRNAs are single-stranded, covalently linked, closed circular RNA molecules found in eukaryotic cells. Some of them act as miRNA sponge to regulate target genes and a couple of others are capable to encode protein products. In Cryptococcus neoformans, seventy-three circRNAs were reported lately by our laboratory without characterizing their functions. One of them, circCNYPT5, is derived from the gene YPT5 which putatively encodeds a Rab5 GPTase which has important roles in endocytosis and vesicle fusion in eukaryotic cells. This proposal is aimed to investigate the biological function of circCNYPT5 and its host gene YPT5 in C. neoformans. Utilizing the established CRISPR-Cas9 editing system for C. neoformans, we are going to create circCNYPT5 and YPT5 deficicinet mutants. Other approaches are also taken, e.g. overexpression of circCNYPT5，to virtually defined the roles of circCNYPT5 and YPT5 in the virulence of the pathogen. The 73 cloned cirRNA expression condition and regulation will also be collected by large-scale of qRT-PCR in order to lay a foundation for further study.