title: Antifungal activity of amiodarone is mediated by disruption of calcium homeostasis.
abstract: The antiarrhythmic drug amiodarone was recently demonstrated to have novel broad range fungicidal activity. We provide evidence that amiodarone toxicity is mediated by disruption of Ca2+ homeostasis in Saccharomyces cerevisiae. In mutants lacking calcineurin and various Ca2+ transporters, including pumps (Pmr1 and Pmc1), channels (Cch1/Mid1 and Yvc1), and exchangers (Vcx1), amiodarone sensitivity correlates with cytoplasmic calcium overload. Measurements of cytosolic Ca2+ by aequorin luminescence demonstrate a biphasic response to amiodarone. An immediate and extensive calcium influx was observed that was dose-dependent and correlated with drug sensitivity. The second phase consisted of a sustained release of calcium from the vacuole via the calcium channel Yvc1 and was independent of extracellular Ca2+ entry. To uncover additional cellular pathways involved in amiodarone sensitivity, we conducted a genome-wide screen of nearly 5000 single-gene yeast deletion mutants. 36 yeast strains with amiodarone hypersensitivity were identified, including mutants in transporters (pmr1, pdr5, and vacuolar H+-ATPase), ergosterol biosynthesis (erg3, erg6, and erg24), intracellular trafficking (vps45 and rcy1), and signaling (ypk1 and ptc1). Of three mutants examined (vps45, vma3, and rcy1), all were found to have defective calcium homeostasis, supporting a correlation with amiodarone hypersensitivity. We show that low doses of amiodarone and an azole (miconazole, fluconazole) are strongly synergistic and exhibit potent fungicidal effects in combination. Our findings point to the potentially effective application of amiodarone as a novel antimycotic, particularly in combination with conventional antifungals.
authors.affiliation: Department of Physiology, The Johns Hopkins University, Baltimore, Maryland 21205, USA.
authors.forename: Soma Sen
authors.initials: SS
authors.lastname: Gupta
authors.forename: Van-Khue
authors.initials: VK
authors.lastname: Ton
authors.forename: Veronica
authors.initials: V
authors.lastname: Beaudry
authors.forename: Samuel
authors.initials: S
authors.lastname: Rulli
authors.forename: Kyle
authors.initials: K
authors.lastname: Cunningham
authors.forename: Rajini
authors.initials: R
authors.lastname: Rao
mesh_terms: D000638:Amiodarone / Q000494:pharmacology*; D000935:Antifungal Agents / Q000494:pharmacology*; D019703:Calcineurin / Q000172:deficiency / Q000235:genetics / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000235:genetics; D002135:Calcium-Binding Proteins / Q000235:genetics; D000252:Calcium-Transporting ATPases / Q000235:genetics; D004357:Drug Synergism; D015725:Fluconazole / Q000494:pharmacology; D017353:Gene Deletion; D006706:Homeostasis / Q000187:drug effects*; D008825:Miconazole / Q000494:pharmacology; D018832:Molecular Chaperones; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D050052:TRPC Cation Channels
chemical_list: D000935:Antifungal Agents; D015220:Calcium Channels; D002135:Calcium-Binding Proteins; D018832:Molecular Chaperones; C101767:SSC1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D050052:TRPC Cation Channels; C446509:Yvc1 protein, S cerevisiae; D008825:Miconazole; D015725:Fluconazole; D019703:Calcineurin; D000252:Calcium-Transporting ATPases; D000638:Amiodarone; D002118:Calcium