Antifungal drug resistance evoked via RNAi-dependent epimutations

ABSTRACT: Here we show that the human fungal pathogen Mucor circinelloides develops spontaneous resistance to the antifungal drug FK506 via two distinct mechanisms. One involves Mendelian mutations that confer stable drug resistance and the other via an epigenetic RNA interference (RNAi)-mediated pathway that results in unstable drug resistance. The peptidyl-prolyl isomerase FKBP12 interacts with FK506 to form a complex that inhibits the protein phosphatase calcineurin. In M. circinelloides, inhibition of calcineurin by FK506 blocks the transition to hyphae and enforces yeast growth. Mutations in the fkbA gene encoding FKBP12 or the calcineurin cnbR or cnaA genes confer FK506 resistance, restoring hyphal growth in the presence of this drug. In parallel, RNAi is spontaneously triggered to silence the FKBP12 fkbA gene, giving rise to drug-resistant epimutants. FK506-resistant epimutants readily reverted to the drug-sensitive wild type (WT) phenotype when selection was released by growth without drug. High-throughput small RNA (sRNA) sequencing showed abundant sRNA antisense to fkbA only in the epimutants and not in the WT or revertant strains. Analysis of RNAi mutants revealed components required for the establishment of drug resistant epimutants as well as other factors that constrain or reverse the epimutation pathway. Silencing involves generation of a double stranded RNA trigger intermediate using the fkbA mature mRNA as template. These results uncover a novel epigenetic RNAi-based epimutation mechanism controlling phenotypic plasticity, with possible implications for antimicrobial drug resistance and RNAi regulatory mechanisms in fungi and other eukaryotes.

ORGANISM(S): Mucor lusitanicus

PROVIDER: GSE56353 | GEO | 2014/07/22

SECONDARY ACCESSION(S): PRJNA243024

REPOSITORIES: GEO