Tpo3 and dur3, Aspergillus fumigatus Plasma Membrane Regulators of Polyamines, Regulate Polyamine Homeostasis and Susceptibility to Itraconazole.

Mingcong Chen,Lei Li,Guowei Zhong,Lei Tang,Sha Wang,Jun Zhu

doi:10.3389/fmicb.2020.563139

Abstract

Aspergillus fumigatus is a well-known opportunistic pathogen that causes invasive aspergillosis (IA) infections, which have high mortality rates in immunosuppressed individuals. Long-term antifungal drug azole use in clinical treatment and agriculture results in loss of efficacy or drug resistance. Drug resistance is related to cellular metabolites and the corresponding gene transcription. In this study, through untargeted metabolomics and transcriptomics under itraconazole (ITC) treatment, we identified two plasma membrane-localized polyamine regulators tpo3 and dur3, which were important for polyamine homeostasis and susceptibility to ITC in A. fumigatus. In the absence of tpo3 and/or dur3, the levels of cytoplasmic polyamines had a moderate increase, which enhanced the tolerance of A. fumigatus to ITC. In comparison, overexpression of tpo3 or dur3 induced a drastic increase in polyamines, which increased the sensitivity of A. fumigatus to ITC. Further analysis revealed that polyamines concentration-dependently affected the susceptibility of A. fumigatus to ITC by scavenging reactive oxygen species (ROS) at a moderate concentration and promoting the production of ROS at a high concentration rather than regulating drug transport. Moreover, inhibition of polyamine biosynthesis reduced the intracellular polyamine content, resulted in accumulation of ROS and enhanced the antifungal activity of ITC. Interestingly, A. fumigatus produces much lower levels of ROS under voriconazole (VOC) treatment than under ITC-treatment. Accordingly, our study established the link among the polyamine regulators tpo3 and dur3, polyamine homeostasis, ROS content, and ITC susceptibility in A. fumigatus.

Highlights

Aspergillus fumigatus, an opportunistic human pathogen in immunocompromised individuals, is a major invasive fungus
Considering the finding that ITC treatment resulted in mild accumulation of Spd in mycelial cells, we sought to determine whether there is a relationship between polyamine utilization and antifungal drug resistance
When 0.3 mM polyamines were combined with VOC or CS, no detectable effect on colony growth was observed in class II (Figures 2D,E), suggesting that there was no obvious interrelationship between 0.3 mM polyamines and these two antifungal agents

Summary

Introduction

Aspergillus fumigatus, an opportunistic human pathogen in immunocompromised individuals, is a major invasive fungus. A. fumigatus spores are ubiquitous in the atmosphere. Inhalation exposure to these spores is associated with sinusitis, severe asthma, and even potentially lethal invasive infections for people with weakened immune systems, which are a challenge in global public health tpo and dur Regulate Itraconazole Susceptibility (Romani, 2011; van de Veerdonk et al, 2017; Latge and Chamilos, 2019). With the widespread and continued use of azole drugs in the clinical and agriculture settings, the rate of A. fumigatus drug-resistant strains has steadily risen over the years (Snelders et al, 2008; Arendrup, 2014; Rybak et al, 2019). A comprehensive understanding of the molecular mechanisms underlying azole resistance can provide theoretical support for the clinical therapy of IA

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