申克孢子丝菌致病相关群体感应分子的筛选与作用机制初探

In recent years, the incidence of sporotrichosis caused by the dimorphic fungus Sporothrix schenckii, especially disseminated and systemic infections has increased throughout the world due to an increase of patients with immunodeficiency and immunosuppression, which has been severely threaten the health of human. It has become one focus of attention in the field of medical mycology. The current studies have shown that quorum sensing was related with the pathogenicity of pathogen. A few studies was done in fungi. The studies of some dimorphic fungi found that the quorum sensing was mediated by the extracellular quorum-sensing molecules, which could act on the PKC-MAPK, cAMP-PKA signal pathways, regulate the dimorphic conversion and affect its pathogenicity. But the correlated studis about Sporothrix schenckii has not yet shown. In this study, the quorum-sensing molecule in Sporothrix schenckii will be isolated and identified by the phenotypic changes of cell growth, differentiation and dimorphic conversion, according to cultures at the different cell density. The molecular mechanism of this quorum-sensing molecule well be revealed by analyzing the effect of the target genes in the PKC-MAPK and cAMP-PKA signal pathways, cell wall integrity and virulence. These will help to elucidate the relationship between the quorum-sensing molecule and the pathogenicity of this fungus, and it is of great significance for the prevention and treatment of sporotrichosis.

近年来，由于免疫缺陷及受损患者增多，导致全球范围内二相型真菌申克孢子丝菌感染，特别是播散性及全身性感染呈逐年上升趋势，严重地威胁人类的健康，已成为医学真菌学研究领域关注的热点之一。近来研究表明，群体感应现象与病原菌的致病性密切相关。目前真菌群体感应现象的相关研究较少。有些二相型真菌的研究发现，其产生的胞外群体感应分子可作用于PKC-MAPK、cAMP-PKA等信号转导途径，调控二相型转换，影响其致病性。但尚未见申克孢子丝菌的相关研究报道。本研究拟根据不同细胞密度培养时，申克孢子丝菌的生长、分化及二相型转换等表型变化，筛选、鉴定群体感应分子；分析其对PKC-MAPK、cAMP-PKA等信号转导途径靶基因、细胞壁成分及菌株毒力的影响，揭示该群体感应分子的调控机制，阐明其与致病性的关系，对预防和控制孢子丝菌病具有重要意义。

近年来，由于免疫缺陷及受损患者增多，导致全球范围内二相型真菌申克孢子丝菌感染，特别是播散性及全身性感染呈逐年上升趋势，严重地威胁人类的健康，已成为医学真菌学研究领域关注的热点之一。近来研究表明，群体感应现象与病原菌的致病性密切相关。目前真菌群体感应现象的相关研究较少。某些二相型真菌的研究发现，其产生的胞外群体感应分子可通过信号转导调控二相型转换，影响其致病性。但尚未见申克孢子丝菌的相关研究报道。.本课题以分离自临床播散性肺孢子丝菌病患者标本的申克孢子丝菌高毒力菌株为研究对象，通过对比分析酵母相与菌丝相代谢产物，发现了法尼醇及其他不同于已知真菌群体感应分子的化合物，作为群体感应分子，在申克孢子丝菌群体感应、二相型转换及致病过程中起重要作用。分析二相型转录组数据及T-DNA插入突变基因信息，发现在群体感应分子作用下，信号转导通路相关激酶丝氨酸/苏氨酸蛋白激酶、组氨酸激酶及磷脂酰肌醇激酶等表达上调，可调控群体感应现象。利用比较基因组学、表观遗传学等技术，解析MAPK信号转导通路的丝氨酸/苏氨酸蛋白激酶基因功能发现，该基因参与调控群体感应现象，影响二相型转换，改变菌株形态、细胞组成及毒力等生物学性状，与致病性形成密切相关。该发现加深了对申克孢子丝菌群体感应和二相型转换发生和调控的认知，为明确其毒力产生的调控机制、认识致病性形成过程奠定有力的基础，对有效地预防和控制孢子丝菌病具有重要意义，也可为其他二相型真菌的相关研究提供参考。