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Gene expression modulation by paraquat-induced oxidative stress conditions in P. brasiliensis

ABSTRACT: Paracoccidioides brasiliensis is a thermodimorphic fungus associated with paracoccidioidomycosis (PCM), the most common systemic mycosis in Latin America. The infection is initiated by inhalation of environmental dispersed conidia produced by the saprophytic phase of the fungus. In the lungs, P. brasiliensis assumes the parasitic yeast form and must cope with the adverse conditions imposed by cells of the host immune system, which includes a harsh environment highly concentrated in reactive oxygen species (ROS). In this work, we used the ROS-generating agent paraquat to experimentally simulate oxidative stress conditions in order to evaluate the stress-induced modulation in gene expression of cultured P. brasiliensis yeast cells using a microarray hybridization approach.

ORGANISM(S): Paracoccidioides brasiliensis

PROVIDER: GSE41148 | GEO | 2013/06/14

SECONDARY ACCESSION(S): PRJNA176420

REPOSITORIES: GEO

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Project description:Paracoccidioides brasiliensis is a thermodimorphic fungus associated with paracoccidioidomycosis (PCM), the most common systemic mycosis in Latin America. The infection is initiated by inhalation of environmental dispersed conidia produced by the saprophytic phase of the fungus. In the lungs, P. brasiliensis assumes the parasitic yeast form and must cope with the adverse conditions imposed by cells of the host immune system, which includes a harsh environment highly concentrated in reactive oxygen species (ROS). In this work, we used the ROS-generating agent paraquat to experimentally simulate oxidative stress conditions in order to evaluate the stress-induced modulation in gene expression of cultured P. brasiliensis yeast cells using a microarray hybridization approach. Microarray hybridizations were carried out with RNA obtained from cells treated with paraquat (0.5 or 5.0 mM) for 5 hours. The RNA obtained from cells unexposed to paraquat was taken as reference. Each treatment was analyzed with four independent hybridizations (two pairs of dye-swapped hybridizations), using RNA from two biological replicas. The data has been filtered, normalized and adjusted as described in the "data processing" box for each individual sample. Dye swap consistency checking has been performed between equivalent experimental pairs with the aid of the software TIGR MIDAS v2.19 and inconsistent spots have been flagged and excluded from further analyses. The values obtained from each dye swap pair have been averaged and consolidated into a single data file, generating a total of 8 hybridization files (four from each treatment concentration). These files have been loaded into the software TIGR Multi-Experiment Viewer, v.3.01. Experiments were then normalized and genes that displayed statistically significant modulation were identified by one-way ANOVA, considering p < 0.01 as a cutoff value. A list of statisticaly significant, modulated genes was created, showing the average log ratio for each one of these genes, within each time point

Project description:The fungi of Paracoccidioides spp. genus are the causative agents of paracoccidioidomycosis (PCM), a systemic mycosis endemic to Latin America. This fungus is considered a facultative intracellular pathogen that is able to survive and replicate inside macrophages. The survival of the fungus during infection depends on its adaptability to various conditions, such as nitrosative/oxidative stress produced by the host immune cells, particularly alveolar macrophages. Currently, there is little knowledge about the P. brasiliensis signaling pathways involved in the fungus evasion mechanism of the host defense response. However, it is known that some of these pathways are triggered by reactive oxygen species and reactive nitrogen species (ROS/RNS) produced by host cells. Considering that the effects of NO (nitric oxide) on pathogens are concentration dependent, such effects could alter the redox state of cysteine residues by influencing (activating or inhibiting) a variety of protein functions, notably S-nitrosylation, a highly important NO-dependent posttranslational modification that regulates cellular functions and signaling pathways. It has been demonstrated by our group that P. brasiliensis yeast cells proliferate when exposed to low NO concentrations. Thus, this work investigated the modulation profile of S-nitrosylated proteins of P. brasiliensis, as well as identifying S-nitrosylation sites after treatment with RNS. Through mass spectrometry analysis (LC-MS/MS) and label-free quantification, it was possible to identify 474 proteins in the S-nitrosylated proteome study. With this approach, we observed that proteins treated with NO at low concentrations presented a proliferative response pattern, with several proteins involved in cellular cycle regulation and growth being activated. These proteins appear to play important roles in fungal virulence. On the other hand, proteins stimulated by high NO concentrations exhibited a survival response pattern, which may help to elucidate RNS antifungal properties and identify potential molecular targets for the development of new drugs in the future

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Gene expression modulation by paraquat-induced oxidative stress conditions in P. brasiliensis

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