New customized expression microarray for Aspergillus fumigatus: effect of temperature on the transcriptome during the earliest steps of germination

Ref ID: 19596

Author:

M Sueiro-Olivares1*, JV Fernández-Molina1, A Abad-Dí­az-de-Cerio1, X Guruceaga1, E Gorospe3,
E Pascual3, A Ramí­rez-Garcí­a2, J Garaizar2, FL Hernando1, J Margareto3, A Rementerí­a1

Author address:

1Department of Immunology, Microbiology and Parasitology, University of the Basque Country
(UPV/EHU), Leioa, Spain
2Department of Immunology, Microbiology and Parasitology, University of the Basque Country
(UPV/EHU), Vitoria-Gasteiz, Spain
3Tecna

Full conference title:

6th Advances Against Aspergillosis 2014

Abstract:

Purpose:
The aim of this study was to validate a new customized expression microarray designed by our group
that covering the entire genome of A. fumigatus to improve our understanding of the pathogenesis of
this mold. In this study, we wanted to analyze the effect of temperature on the transcriptomes of this
fungus at the first steps of germination in order to identify functional changes and expressed genes
related to virulence.
Methods:
The microarray was designed using the information available from the NCBI database and a
commercial microarray design system (e-Array of Agilent Technologies, Santa Clara, CA, USA). This
microarray includes 9,630 genes of A. fumigatus, 62 quality control genes and positive and negative
controls included automatically by the design system. In order to validate this microarray, we studied
the transcriptome of germinated conidia at 37 and 24ºC after 6.5 and 18 h of incubation, respectively.
Three independent extractions of total RNA obtained from each condition were hybridized with the
microarray, and the expressions results were statistically compared. The expression results were
validated by the selection of twenty overexpressed genes and their retrotranscription qPCR analysis.
Finally, differentially expressed genes were classified according to their biological function.
Results:
The microarray data revealed 1,253 genes that were differentially expressed at 24 or 37ºC.
Retrotranscription qPCR results confirmed the differential expression of the selected genes at different
temperatures with a Pearson’s correlation value of 0.89. According to our results, A. fumigatus
modifies the expression of genes related to metabolism, cell rescue, defense and virulence, transport
and energy in order to adapt to new conditions. Furthermore, some genes related to virulence were
also overexpressed in the earliest steps of conidial germination but only following growth at a high
temperature. Some of these overexpressed genes encoded proteins mainly related to a wide range of
allergens (Asp F1, Asp F2 and MnSOD), while others are genes known to be involved in gliotoxin
biosynthesis (GliP and GliZ) or nitrogen (NiiA and NiaD) or iron (HapX, SreA, SidD and SidC)
metabolism.
Conclusion:
This study provides strong evidence to suggest that there is a connection between host temperature
and the adaptation and virulence of A. fumigatus. It seems that simply with a heat shock of 37ºC for
a few hours, which could be correspond to the initial contact with human host, the fungus begins
a quick process of adaptation, consisting of an increase in the germination rate and change in gene
expression. These changes could help to colonize the lung and, ultimately, to infect the host, if
the immune system is weakened. Moreover, the microarray used provides the opportunity to carry
out more expression studies comparing the transcriptome of this pathogen growing under different
laboratory conditions, and even during murine or human cell infections, and such experiments would
provide a great deal of data that could improve our understanding of A. fumigatus pathogenesis.

Abstract Number: 121

Conference Year: 2014

Link to conference website: http://www.AAA2014.org

New link: NULL

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