Transcriptomic analysis of synergy between antifungal drugs and iron chelators for alternative antifungal therapies

There is an urgent need to improve the efficacy and range of antifungal drugs due to a global increase in invasive fungal infections, which are difficult to treat and are associated with high rates of mortality. Developing new drugs is expensive and time consuming and synergistic therapies that enhance the efficacy of current drugs are an alternative approach. Iron chelators have been used as antifungal synergents in salvage therapy, however, how these cause synergy are unknown. This thesis aims to use a transcriptomic approach to understand the mechanistic detail of antifungal-chelator synergy in the pathogen Cryptococcus to find potential antifungal targets. It focuses on amphotericin B (AMB) and lactoferrin (LF) synergy and voriconazole (VRC) and EDTA antagonism upon screening the interactions of various antifungal - chelator combinations in Cryptococcus. LF was found to enhance the antifungal effect of AMB in two ways: via the dysregulation of stress responses and metal homeostasis that disrupted the cell’s ability to mount an appropriate stress response, and by overwhelming the cell’s stress response via the cumulative strain from ER stress, disruption of transmembrane transport processes and increased metal dysregulation. Metal homeostasis was vital to both processes and the direct disruption of metal homeostasis, via deletion of iron (Aft1, Cir1 and HapX) and zinc (Zap1 and Zap104) regulating transcription factors, resulted in increased AMB susceptibility. Analysis of drug-binding domains in Zap1 and Zap104 found these to contain druggable sites and be potential antifungal drug targets. EDTA in the presence of VRC was found to disrupt mitochondrial functions along with an up-regulation of drug efflux genes, suggesting a potential mechanism of antagonism by mediating the efflux of intracellular VRC. Overall, metal regulation is important for resisting antifungal stress and is a potential antifungal strategy, where Zap1 is a potential antifungal drug target

Xenopus

This book focuses on the amphibian, Xenopus, one of the most commonly used model animals in the biological sciences. Over the past 50 years, the use of Xenopus has made possible many fundamental contributions to our knowledge in cell biology, developmental biology, molecular biology, and neurobiology. In recent years, with the completion of the genome sequence of the main two species and the application of genome editing techniques, Xenopus has emerged as a powerful system to study fundamental disease mechanisms and test treatment possibilities. Xenopus has proven an essential vertebrate model system for understanding fundamental cell and developmental biological mechanisms, for applying fundamental knowledge to pathological processes, for deciphering the function of human disease genes, and for understanding genome evolution. Key Features Provides historical context of the contributions of the model system Includes contributions from an international team of leading scholars Presents topics spanning cell biology, developmental biology, genomics, and disease model Describes recent experimental advances Incorporates richly illustrated diagrams and color images Related Titles Green, S. L. The Laboratory Xenopus sp. (ISBN 978-1-4200-9109-0) Faber, J. & P. D. Nieuwkoop. Normal Table of Xenopus laevis (Daudin): A Systematical & Chronological Survey of the Development from the Fertilized Egg till the End of Metamorphosis (ISBN 978-0-8153-1896-5) Jarret, R. L. & K. McCluskey. The Biological Resources of Model Organisms (ISBN 978-1-0320-9095-5