Grant: Discovery Grants Program - Individual

Journal articlesJ# refer to Dahms' CCV Background The highly dynamic fungal cell envelope is the first line of defense to chemical challenge and plays an important role in morphogenesis and fungal-host interactions. Fungi use a number of strategies to maintain cell wall integrity, including monitoring and responding to environmental challenges through signal-transduction cascades. The yeast cell envelope helps regulate, delay and arrest cell division in response to external stress. In Candida albicans, glycosylated proteins coat the outer surface anchored to the cell wall mainly through glycosylphosphatidylinositol. Our understanding of the specific role of candidal glycosylphosphatidylinositol-proteins in wall integrity, cell proliferation and morphogenesis is limited, but an elegant model in Saccharomyces cerevisiae proposes that environmental stress perturbs cell wall elasticity, which activates GPI-mechanosensors and morphogenesis. Another set of proteins called adhesins are known to orchestrate yeast interactions, including those with the host. We have demonstrated how essential oils remodel the C. albicans' cell envelopeJ1,J4-5,J8-12,J23, increasing adhesion and altering spindle behaviour, providing links between adhesion, wall integrity and cell divisionJ1. In the long-term, the proposed research program aims to identify how targeted xenobiotics impact fungal cell wall integrity pathways, cell division, morphogenesis, fungal-host interactions, and their interrelationship. In the short term, we will extend our correlative microscopy assays to understand in C. albicans: 1. the mechanism of mechanosensor detection of external stimuli that activate cell wall integrity pathways; 2. the role of glyocosylphosphatidylinositol-proteins and mechanoreceptors, in stress-induced signaling cross-talk, and; 3. the role of stress-induced signaling cross-talk in wall integrity, cell division and morphogenesis. Scientific Approach Biochemical, molecular, microbiological, and novel correlative microscopy assays will address these objectives. Our recently developed correlative microscopy live cell assays, simultaneously imaging with atomic force-quantitative imaging and laser scanning confocalJ22, will simultaneously monitor fungal cell envelope remodeling while tracking membrane proteins and cytosolic biochemical changes (e.g. signaling pathways), respectively. Outcomes Such a strategy will build a more complete picture of stress propagation, defining how the stress signal is transduced through the cell wall integrity system, eventually impacting major cellular processes such as candidal morphogenesis and cell division. The proposed research will train the next generation of diverse interdisciplinary scientists, and contribute to our fundamental understanding of fungal cell wall integrity pathways and cell wall quality control at the molecular level, informing the development of fungicides and antifungals for agriculture and medicine.