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Updated: Aug 24, 2026
Gene Expression Profiling of Infecting Microbes Using a Digital Bar-coding Platform
Published on: January 13, 2016
Identification of genes preferentially expressed in the pathogenic yeast phase of Paracoccidioides brasiliensis,
E R Marques1, M E S Ferreira, R D Drummond
1Departamento de Ciências Farmacêuticas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av. do Café S/N, CEP 14040-903, Ribeirão Preto, São Paulo, Brazil.
Abstract:
Paracoccidioides brasiliensis, a thermodimorphic fungus, is the causative agent of paracoccidioidomycosis (PCM), the most prevalent systemic mycosis in Latin America. Pathogenicity appears to be intimately related to the dimorphic transition from the hyphal to the yeast form, which is induced by a shift from environmental temperature to the temperature of the mammalian host. Little information is available on the P. brasiliensis genes that are necessary during the pathogenic phase. We have therefore undertaken Suppression Subtraction Hybridization (SSH) and macroarray analyses with the aim of identifying genes that are preferentially expressed in the yeast phase. Genes identified by both procedures as being more highly expressed in the yeast phase are involved in basic metabolism, signal transduction, growth and morphogenesis, and sulfur metabolism. In order to test whether the observed changes in gene expression reflect the differences between the growth conditions used to obtain the two morphological forms rather than differences intrinsic to the cell types, we performed real-time RT-PCR experiments using RNAs derived from both yeast cells and mycelia that had been cultured at 37 degrees C and 26 degrees C in either complete medium (YPD or Sabouraud) or minimal medium. Twenty genes, including AGS1 (alpha-1,3-glucan synthase) and TSA1 (thiol-specific antioxidant), were shown to be more highly expressed in the yeast cells than in the hyphae. Although their levels of expression could be different in rich and minimal media, there was a general tendency for these genes to be more highly expressed in the yeast cells.
Insights
Paracoccidioides brasiliensis yeast cells express specific genes crucial for pathogenicity. Identifying these genes aids in understanding and combating paracoccidioidomycosis (PCM), a significant fungal infection.
Area of Science:
- Mycology
- Medical Mycology
- Molecular Biology
Background:
- Paracoccidioides brasiliensis causes paracoccidioidomycosis (PCM), a prevalent systemic mycosis in Latin America.
- Pathogenicity is linked to the fungus's dimorphic transition from hyphal to yeast form, triggered by host temperature.
- Limited knowledge exists regarding P. brasiliensis genes essential for its pathogenic yeast phase.
Purpose of the Study:
- To identify genes preferentially expressed in the yeast phase of P. brasiliensis.
- To understand the molecular basis of fungal pathogenicity during the yeast form.
Main Methods:
- Suppression Subtraction Hybridization (SSH) and macroarray analyses were employed to identify differentially expressed genes.
- Real-time RT-PCR experiments validated gene expression levels under various culture conditions (temperature and media).
Main Results:
- SSH and macroarray analyses revealed genes involved in metabolism, signal transduction, growth, morphogenesis, and sulfur metabolism are upregulated in the yeast phase.
- Twenty genes, including AGS1 and TSA1, were confirmed to be more highly expressed in yeast cells compared to hyphae via RT-PCR.
- A general trend of increased gene expression in the yeast form was observed, irrespective of media richness.
Conclusions:
- The study identified key genes upregulated in the pathogenic yeast form of P. brasiliensis.
- These findings contribute to understanding the molecular mechanisms underlying fungal dimorphism and pathogenicity.
- The identified genes represent potential targets for future therapeutic strategies against PCM.
