title: Transcriptome and network analyses in Saccharomyces cerevisiae reveal that amphotericin B and lactoferrin synergy disrupt metal homeostasis and stress response.
abstract: Invasive fungal infections are difficult to treat. The few available antifungal drugs have problems with toxicity or efficacy, and resistance is increasing. To overcome these challenges, existing therapies may be enhanced by synergistic combination with another agent. Previously, we found amphotericin B (AMB) and the iron chelator, lactoferrin (LF), were synergistic against a range of different fungal pathogens. This study investigates the mechanism of AMB-LF synergy, using RNA-seq and network analyses. AMB treatment resulted in increased expression of genes involved in iron homeostasis and ATP synthesis. Unexpectedly, AMB-LF treatment did not lead to increased expression of iron and zinc homeostasis genes. However, genes involved in adaptive response to zinc deficiency and oxidative stress had decreased expression. The clustering of co-expressed genes and network analysis revealed that many iron and zinc homeostasis genes are targets of transcription factors Aft1p and Zap1p. The aft1Δ and zap1Δ mutants were hypersensitive to AMB and H2O2, suggesting they are key regulators of the drug response. Mechanistically, AMB-LF synergy could involve AMB affecting the integrity of the cell wall and membrane, permitting LF to disrupt intracellular processes. We suggest that Zap1p- and Aft1p-binding molecules could be combined with existing antifungals to serve as synergistic treatments.
authors.affiliation: School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Kensington, New South Wales, Australia.
authors.forename: Chi Nam Ignatius
authors.initials: CN
authors.lastname: Pang
authors.affiliation: School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Yu-Wen
authors.initials: YW
authors.lastname: Lai
authors.affiliation: School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Leona T
authors.initials: LT
authors.lastname: Campbell
authors.affiliation: Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, NSW, Australia.|Centre for Infectious Diseases and Microbiology, Institute of Clinical Pathology and Medical Research, Westmead Hospital, Sydney Medical School, University of Sydney, Westmead, NSW, Australia.
authors.forename: Sharon C-A
authors.initials: SC
authors.lastname: Chen
authors.affiliation: School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia.|Marie Bashir Institute for Infectious Diseases and Biosecurity, University of Sydney, Sydney, NSW, Australia.
authors.forename: Dee A
authors.initials: DA
authors.lastname: Carter
authors.affiliation: School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Kensington, New South Wales, Australia.
authors.forename: Marc R
authors.initials: MR
authors.lastname: Wilkins
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000666:Amphotericin B / Q000494:pharmacology*; D000935:Antifungal Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D020869:Gene Expression Profiling; D063990:Gene Ontology; D006706:Homeostasis / Q000187:drug effects; D007501:Iron / Q000378:metabolism; D007781:Lactoferrin / Q000494:pharmacology*; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D059467:Transcriptome
chemical_list: D000935:Antifungal Agents; D029701:Saccharomyces cerevisiae Proteins; D000666:Amphotericin B; D000255:Adenosine Triphosphate; D007501:Iron; D017868:Cyclic AMP-Dependent Protein Kinases; D007781:Lactoferrin