Tamayo Diana, Muñoz José F, Almeida Agostinho J, Puerta Juan D, Restrepo Ángela, Cuomo Christina A, McEwen Juan G, Hernández Orville
Cellular and Molecular Biology Unit, Corporación para Investigaciones Biológicas, Medellín, Colombia; Institute of Biology, Universidad de Antioquia, Medellín, Colombia; School of Microbiology, Universidad de Antioquia, Medellín, Colombia.
Cellular and Molecular Biology Unit, Corporación para Investigaciones Biológicas, Medellín, Colombia; Institute of Biology, Universidad de Antioquia, Medellín, Colombia; Broad Institute of MIT and Harvard, Cambridge, MA, USA.
Fungal Genet Biol. 2017 Mar;100:22-32. doi: 10.1016/j.fgb.2017.01.005. Epub 2017 Jan 16.
Dimorphic human pathogenic fungi interact with host effector cells resisting their microbicidal mechanisms. Yeast cells are able of surviving within the tough environment of the phagolysosome by expressing an antioxidant defense system that provides protection against host-derived reactive oxygen species (ROS). This includes the production of catalases (CATs). Here we identified and analyzed the role of CAT isoforms in Paracoccidioides, the etiological agent of paracoccidioidomycosis. Firstly, we found that one of these isoforms was absent in the closely related dimorphic pathogen Coccidioides and dermatophytes, but all of them were conserved in Paracoccidioides, Histoplasma and Blastomyces species. We probed the contribution of CATs in Paracoccidioides by determining the gene expression levels of each isoform through quantitative RT-qPCR, in both the yeast and mycelia phases, and during the morphological switch (transition and germination), as well as in response to oxidative agents and during interaction with neutrophils. PbCATP was preferentially expressed in the pathogenic yeast phase, and was associated to the response against exogenous HO. Therefore, we created and analyzed the virulence defects of a knockdown strain for this isoform, and found that CATP protects yeast cells from HO generated in vitro and is relevant during lung infection. On the other hand, CATA and CATB seem to contribute to ROS homeostasis in Paracoccidioides cells, during endogenous oxidative stress. CAT isoforms in Paracoccidioides might be coordinately regulated during development and dimorphism, and differentially expressed in response to different stresses to control ROS homeostasis during the infectious process, contributing to the virulence of Paracoccidioides.
双态性人类致病真菌与宿主效应细胞相互作用，抵抗其杀菌机制。酵母细胞能够在吞噬溶酶体的恶劣环境中存活，通过表达一种抗氧化防御系统来抵御宿主产生的活性氧（ROS）。这包括过氧化氢酶（CATs）的产生。在此，我们鉴定并分析了CAT同工型在副球孢子菌（副球孢子菌病的病原体）中的作用。首先，我们发现其中一种同工型在密切相关的双态性病原体球孢子菌和皮肤癣菌中不存在，但在副球孢子菌、组织胞浆菌和芽生菌属物种中均保守存在。我们通过定量RT-qPCR测定每种同工型在酵母和菌丝体阶段、形态转换（转变和萌发）过程中、对氧化试剂的反应以及与中性粒细胞相互作用期间的基因表达水平，来探究CATs在副球孢子菌中的作用。PbCATP在致病性酵母阶段优先表达，并与对外源H₂O₂的反应相关。因此，我们构建并分析了该同工型敲低菌株的毒力缺陷，发现CATP可保护酵母细胞免受体外产生的H₂O₂的损伤，并且在肺部感染过程中发挥重要作用。另一方面，CATA和CATB似乎在内源性氧化应激期间有助于副球孢子菌细胞中的ROS稳态。副球孢子菌中的CAT同工型可能在发育和双态性过程中受到协同调控，并在感染过程中对不同应激做出差异表达，以控制ROS稳态，从而促进副球孢子菌的毒力。
