Identification of Cryptococcus neoformans Temperature-Regulated Genes with a Genomic-DNA Microarray

Abstract

The ability to survive and proliferate at 37°C is an essential virulence attribute of pathogenic microorganisms. A partial-genome microarray was used to profile gene expression in the human-pathogenic fungus Cryptococcus neoformans during growth at 37°C. Genes with orthologs involved in stress responses were induced during growth at 37°C, suggesting that a conserved transcriptional program is used by C. neoformans to alter gene expression during stressful conditions. A gene encoding the transcription factor homolog Mga2 was induced at 37°C and found to be important for high-temperature growth. Genes encoding fatty acid biosynthetic enzymes were identified as potential targets of Mga2, suggesting that membrane remodeling is an important component of adaptation to high growth temperatures. mga2⌬ mutants were extremely sensitive to the ergosterol synthesis inhibitor fluconazole, indicating a coordination of the synthesis of membrane component precursors. Unexpectedly, genes involved in amino acid and pyrimidine biosynthesis were repressed at 37°C, but components of these pathways were found to be required for high-temperature growth. Our findings demonstrate the utility of even partial-genome microarrays for delineating regulatory cascades that contribute to microbial pathogenesis.

Characterization and Regulation of the Trehalose Synthesis Pathway and Its Importance in the Pathogenicity of Cryptococcus neoformans

“…Because temperature sensitivity of the trehalose pathway is so important in both its regulation and survival at high temperatures for C. neoformans, an attempt was made to determine whether there were any links between this pathway and several signaling pathways associated with high-temperature growth. Therefore, we examined several signaling mutants (cna1 [42], mga1 [33], and cpa1/cpa2 [54]) for their involvement in expression of the trehalose pathway genes (TPS1, TPS2, and NTH1). We found that there was no apparent difference as shown by Northern blot analysis in the expression of the three trehalose pathway genes in these mutants compared to trehalose gene expression patterns in H99 at 2 h of exposure to 37°C (data not shown).…”

Rewiring of Signaling Networks Modulating Thermotolerance in the Human Pathogen Cryptococcus neoformans

“…We compared our array data of the WT strain to those from other microarray analyses performed independently to identify temperature-regulated or heat-shock responsive genes in C. neoformans (Steen et al 2002;Kraus et al 2004;Chow et al 2007). Steen et al (2002) demonstrated that the tag representing cyclophilin A (CPA1 and CPA2) is expressed at higher levels at 37°than at 25°.…”

Differential gene expression analysis of Paracoccidioides brasiliensis during keratinocyte infection

“…In Schizosaccharomyces pombe, alterations in expression of the rds1 gene were observed when the fungus was subjected to various conditions such as glucose, ammonia and phosphate deprivation and changes in CO 2 concentration and temperature (Ludin et al, 1995). Kraus et al (2004), using a microarray technique, found increased expression of RDS1 in Cryptococcus neofomans maintained at 37 u C and, similarly, Rosa e Silva et al (2008), comparing the yeast at 25 and 37 u C, verified an increase in expression of this gene using RDA.…”