Academy of Military Medical Sciences, Beijing, China; Institute for Disease Control and Prevention of PLA, Beijing, China.
Academy of Military Medical Sciences, Beijing, China; Institute for Disease Control and Prevention of PLA, Beijing, China; Comprehensive Liver Cancer Center, Beijing 302 Hospital, Beijing, China.
Fungal Genet Biol. 2018 Nov;120:30-41. doi: 10.1016/j.fgb.2018.09.003. Epub 2018 Sep 8.
Aspergillus fumigatus is a major pathogen of invasive pulmonary aspergillosis. The small GTPase, Rho1, of A. fumigatus is reported to comprise a potential regulatory subunit of β-1,3-glucan synthase and is indispensable for fungal viability; however, the role of AfRho1 on the growth, cell wall integrity, and pathogenesis of A. fumigatus is still poorly understood. We constructed A. fumigatus mutants with conditional- and overexpression of Rho1 and found that defects of AfRho1 expression led to the reduction of β-1,3-glucan and glucosamine moieties on the cell wall, with down-regulated transcription of genes in the cell wall integrity signaling pathway and a decrease of calcofluor white (CFW)-stimulated mitogen-activated protein kinase (MpkA) phosphorylation and cytoplasmic leakage compared to those of the wild-type strain (WT). In addition, down-regulation of AfRho1 expression caused much higher sensitivity of A. fumigatus to HO and alkaline pH compared to that of WT. Decrease of AfRho1 expression also attenuated the A. fumigatus pathogenicity in Galleria mellonella and inhibited conidial internalization into lung epithelial cells and inflammatory factor release. In contrast, overexpression of Rho1 did not alter A. fumigatus morphology, susceptibility to cell wall stresses, or pathogenicity relative to its parental strain. Taken together, our findings support AfRho1 as an essential regulator of the cell wall integrity, stress response, and pathogenesis of A. fumigatus.
烟曲霉是侵袭性肺曲霉病的主要病原体。据报道，烟曲霉的小分子 GTP 酶 Rho1 是β-1,3-葡聚糖合成酶的潜在调节亚基，对真菌的生存至关重要；然而，AfRho1 在烟曲霉的生长、细胞壁完整性和发病机制中的作用仍知之甚少。我们构建了 Rho1 条件性和过表达的烟曲霉突变体，发现 AfRho1 表达的缺陷导致细胞壁上的β-1,3-葡聚糖和氨基葡萄糖部分减少，细胞壁完整性信号通路的基因转录下调，钙荧光白（CFW）刺激的丝裂原激活蛋白激酶（MpkA）磷酸化和细胞质渗漏减少与野生型菌株（WT）相比。此外，与 WT 相比，AfRho1 表达下调导致烟曲霉对 HO 和碱性 pH 的敏感性大大增加。AfRho1 表达的下调还减弱了烟曲霉在大蜡螟中的致病性，并抑制了分生孢子向肺上皮细胞的内化和炎症因子的释放。相反，与亲本菌株相比，Rho1 的过表达并没有改变烟曲霉的形态、对细胞壁应激的敏感性或致病性。总之，我们的研究结果表明 AfRho1 是烟曲霉细胞壁完整性、应激反应和发病机制的重要调节剂。
