Mitochondrial dysfunctions trigger the calcium signaling-dependent fungal multidrug resistance

Proc Natl Acad Sci U S A. 2020 Jan 21;117(3):1711-1721. doi: 10.1073/pnas.1911560116. Epub 2019 Dec 6.

Abstract

Drug resistance in fungal pathogens has risen steadily over the past decades due to long-term azole therapy or triazole usage in agriculture. Modification of the drug target protein to prevent drug binding is a major recognized route to induce drug resistance. However, mechanisms for nondrug target-induced resistance remain only loosely defined. Here, we explore the molecular mechanisms of multidrug resistance resulted from an efficient adaptation strategy for survival in drug environments in the human pathogen Aspergillus fumigatus We show that mutants conferring multidrug resistance are linked with mitochondrial dysfunction induced by defects in heme A biosynthesis. Comparison of the gene expression profiles between the drug-resistant mutants and the parental wild-type strain shows that multidrug-resistant transporters, chitin synthases, and calcium-signaling-related genes are significantly up-regulated, while scavenging mitochondrial reactive oxygen species (ROS)-related genes are significantly down-regulated. The up-regulated-expression genes share consensus calcium-dependent serine threonine phosphatase-dependent response elements (the binding sites of calcium-signaling transcription factor CrzA). Accordingly, drug-resistant mutants show enhanced cytosolic Ca2+ transients and persistent nuclear localization of CrzA. In comparison, calcium chelators significantly restore drug susceptibility and increase azole efficacy either in laboratory-derived or in clinic-isolated A. fumigatus strains. Thus, the mitochondrial dysfunction as a fitness cost can trigger calcium signaling and, therefore, globally up-regulate a series of embedding calcineurin-dependent-response-element genes, leading to antifungal resistance. These findings illuminate how fitness cost affects drug resistance and suggest that disruption of calcium signaling might be a promising therapeutic strategy to fight against nondrug target-induced drug resistance.

Keywords: Aspergillus fumigatus; calcium signaling; drug resistance; fungi; mitochondrial dysfunctions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkyl and Aryl Transferases / genetics
  • Antifungal Agents / pharmacology
  • Aspergillus fumigatus / drug effects*
  • Aspergillus fumigatus / genetics
  • Calcium Chelating Agents / pharmacology
  • Calcium Signaling / drug effects
  • Calcium Signaling / physiology*
  • Chitin Synthase / genetics
  • Drug Resistance, Fungal / drug effects*
  • Drug Resistance, Fungal / genetics
  • Drug Resistance, Fungal / physiology*
  • Fungal Proteins / genetics
  • Gene Expression Regulation, Fungal / drug effects
  • Heme / analogs & derivatives
  • Heme / biosynthesis
  • Humans
  • Membrane Proteins / genetics
  • Mitochondria / drug effects*
  • Mitochondria / genetics
  • Mitochondria / metabolism*
  • Mitochondrial Diseases / genetics
  • Mitochondrial Diseases / metabolism*
  • Phosphoprotein Phosphatases / metabolism
  • Reactive Oxygen Species
  • Transcription Factors / metabolism
  • Triazoles / pharmacology

Substances

  • Antifungal Agents
  • Calcium Chelating Agents
  • CrzA protein, Aspergillus fumigatus
  • Fungal Proteins
  • Membrane Proteins
  • Reactive Oxygen Species
  • Transcription Factors
  • Triazoles
  • heme a
  • Heme
  • Chitin Synthase
  • Alkyl and Aryl Transferases
  • Phosphoprotein Phosphatases