BioProject

Background The sphingolipid Glucosylceramide (GlcCer) and factors involved in the fungal GlcCer pathways were shown earlier to be an integral part of fungal virulence, especially in fungal replication at 37°C, in neutral/alkaline pH and 5% CO2 environments (e. More...

Background The sphingolipid Glucosylceramide (GlcCer) and factors involved in the fungal GlcCer pathways were shown earlier to be an integral part of fungal virulence, especially in fungal replication at 37°C, in neutral/alkaline pH and 5% CO2 environments (e.g. alveolar spaces). Two mutants (null mutants’ delta-gcs1 and delta-smt1 lacking glucosylceramide synthase 1 gene and C9 sphingolipid methyltransferase 1 gene respectively) of this pathway were attenuated in virulence and have a growth defect at the above-mentioned conditions. These mutants with either no or structurally modified GlcCer located on the cell-membrane have reduced membrane rigidity, which may have altered not only the physical location of membrane proteins but also their expression, as the pathogen’s mode of adaptation to changing need. Importantly, pathogens are known to adapt themselves to the changing host environments by altering their patterns of gene expression. Results By transcriptional analysis of gene expression, we identified six genes whose expression was changed from their wild-type counterpart grown in the same conditions, i.e they became either down regulated or up regulated in these two mutants. The microarray data was validated by real-time PCR, which confirmed their fold change in gene expression. The 6 genes we identified, viz siderochrome-iron transporter (CNAG_02083), monosaccharide transporter (CNAG_05340), glucose transporter (CNAG_03772), membrane protein (CNAG_03912), membrane transport protein (CNAG_00539), and sugar transporter (CNAG_06963), all of which are membrane-localized and have significantly altered gene expression levels. Therefore, we speculate that these genes function either independently or in tandem with a structurally modified cell wall/plasma membrane resulting from the modifications of the GlcCer pathway and thus possibly disrupt trans membrane signaling complex, which in turn contributes to Cryptococcal osmotic, pH, ion homeostasis and its pathobiology. Conclusion Gene expression microarrays identified 6 genes by gene set enrichment analysis and validated by qRT-PCR, which are involved in the trans membrane signaling network in Cryptococcus neoformans, controlling the rigidity of the membrane in neutral-alkaline pH and therefore the pathobiology of the fungus in these conditions. Overall design: WT vs ∆smt1 at pH 4, WT vs ∆smt1 at pH 7.2±0.2, WT vs ∆gcs1 at pH 4, WT vs ∆gcs1 at pH 7.2±0.2 Less...