ERA-NET PathoGenoMics_1.Call_Genomic Approaches to Unravel the Molecular Mechanisms of Pathogenicity in the Humen Fungal Pathogen Candida glabrata - FunPath

The molecular mechanisms driving invasion of mammalian hosts by fungal pathogens pose many scientifically challenging problems but are as yet little understood. The availability of the entire genome sequence of the important fungal pathogen Candida glabrata (Cg) reveals striking similarities and to the non-pathogenic relative yeast Saccharomyces cerevisiae (Sc), opening the door to pursue global genomics approaches to better understand fungal pathogenicity. Cg, a commensal pathogen, accounting for the second most frequent cause for systemic mycoses, causes up to 20% of clinical mycoses. The intrinsically high drug resistance to widely used antifungal drugs such as azoles makes Cg a real threat in infectious diseases. In contrast to Ca, relevant host immune defenses against Cg are unknown. Therefore, FunPath will address at the genome scale the question which candidate Cg genes are necessary to bypass mammalian host defense. Hence, FunPath will identify virulence mechanisms and improve our current understanding of fungal pathogenicity. The main objective of FunPath is to use genomics and a reverse genetic approach to identify Cg genes implicated in pathogenicity. This will be accomplished at the genomewide scale by deleting all genes of major known signaling cascades such as MAP kinase pathways, TOR signaling, cAMP-PKA sensing, RIM101, as well as genes encoding membrane proteins acting as stress sensors or transporters for nutrients, drugs or amino acids. Comparative bioinformatics shall identify putative virulence genes for further molecular and cell-biological characterization, particularly those implicated in the host immune response, signaling and stress response. FunPath will use comparative genomics to exploit molecular knowledge about some of these processes from the evolutionary closely related yeast Sc. Based on described Sc networks, FunPath will infer protein-protein interaction and regulatory networks for Cg relevant to signaling and fungal virulence. Candidate virulence genes will be inactivated, and corresponding Cg mutant strains will be studied with regard to host cell responses, invasiveness, as well as transcriptional indicators. The physiological relevance of potential pathogenicity genes will be analyzed in vitro, ex vivo as well as in vivo, by subjecting genetically altered Cg pathogens to phenotypic profiling, to tests in reconstituted systems, as well as to virulence testing in mammalian and insect models. Finally, FunPath takes advantage of an interdisciplinary approach to identify genes driving invasion of mammalian host cells, as these genetic components could be valuable targets for antifungal drug discovery. Aim of the Project: The principal aim of FunPath is to study an important human fungal pathogen, Candida glabrata, so as to better understand at the genomic level the molecular mechanisms of pathogenicity. FunPath will pursue a pathgenomics approach to identify virulence genes at the genome scale. We shall exploit a gene deletion approach to delete all genes of known signaling pathways, membrane sensors and transporters, as well as transcription factors in the genome of Candida glabrata. Thus, FunPath shall generate both fundamental and applicable knowledge about fungal virulence, underscoring its relevance as state-of-the art approach in functional genomics.