In vivo RNA sequencing reveals a crucial role of Fus3-Kss1 MAPKpathway in Candida glabrata pathogenicity

Candida glabrata is an important and increasingly common pathogen of humans, particularly in immunocompromised hosts. Despite this, little is known about how this fungus causes disease. Here, we applied RNA sequencing and an in vivo invasive infection model to identify the attributes that allow this organism to infect hosts. Fungal transcriptomes show a dramatic increase in the expression of Fus3 and Kss1, two mitogen-activated protein kinases (MAPKs), during invasive infection. We further demonstrate that they are both highly induced under a combination of serum and high CO2 condition. Deletion of both FUS3 and KSS1, but neither gene alone, results in a reduced fungal burden in organs, as well as in gastrointestinal tract in the DSS (Dextran Sulfate Sodium)-induced colitis model. Similarly, the defect in persistence in macrophages and attenuated adhesion to epithelial cells are observed when FUS3 and KSS1 are both disrupted. The fus3 kss1 double mutant also displays defects in the induction of virulence attributes such as genes required for iron acquisition and adhesion, and in the anti-fungal drug tolerance. The putative downstream transcription factors Ste12(1), Ste12(2), Tec1 and Tec2 are found to be involved in the regulation of these virulence attributes. Collectively, our study indicates that an evolutionary conserved MAPK pathway which regulates mating and filamentous growth in Saccharomyces cerevisiae, is critical for C. glabrata pathogenicity. To uncover the signaling pathway contributing to the virulence of C. glabrata, the gene expression profiles of this fungal pathogen at 24 h and 48 h post invasive infection from RNA-seq experiment. The RNA-seq analysis was applied on the kidney, which is frequently the most heavily infected organ with hematogenously disseminated candidiasis.