From Glacier to Sauna: RNA-Seq of the Human Pathogen Black Fungus Exophiala dermatitidis under Varying Temperature Conditions Exhibits Common and Novel Fungal Response

Abstract

Exophiala dermatitidis (Wangiella dermatitidis) belongs to the group of the so-called black yeasts. Thanks in part to its thick and strongly melanized cell walls, E. dermatitidis is extremely tolerant to various kinds of stress, including extreme pH, temperature and desiccation. E. dermatitidis is also the agent responsible for various severe illnesses in humans, such as pneumonia and keratitis, and might lead to fatal brain infections. Due to its association with the human environment, its poly-extremophilic lifestyle and its pathogenicity in humans, E. dermatitidis has become an important model organism. In this study we present the functional analysis of the transcriptional response of the fungus at 1°C and 45°C, in comparison with that at 37°C, for two different exposition times, i.e. 1 hour and 1 week. At 1°C, E. dermatitidis uses a large repertoire of tools to acclimatize, such as lipid membrane fluidization, trehalose production or cytoskeleton rearrangement, which allows the fungus to remain metabolically active. At 45°C, the fungus drifts into a replicative state and increases the activity of the Golgi apparatus. As a novel finding, our study provides evidence that, apart from the protein coding genes, non-coding RNAs, circular RNAs as well as fusion-transcripts are differentially regulated and that the function of the fusion-transcripts can be related to the corresponding temperature condition. This work establishes that E. dermatitidis adapts to its environment by modulating coding and non-coding gene transcription levels and through the regulation of chimeric and circular RNAs.

Proteome of tolerance fine-tuning in the human pathogen black yeast Exophiala dermatitidis

“…In accordance with the findings of a recent study on the transcriptome of this fungus, the highest number of cellular processes is altered by the exposure to low temperature [65], thus indicating the strain's effort to cope with the cold.…”

“…However, other unknown cellular strategies may also have a crucial role in the tolerance and adaptation. Recently, the fusion of distinct mRNAs to produce the necessary proteins once in need has been proposed as a solution for thriving in the natural and in the human-made environment as well as in the human host [65].…”

The Transcriptome of Exophiala dermatitidis during Ex-vivo Skin Model Infection

“…Exophiala dermatitidis has become the most studied species within the group of black yeasts due to its human pathogenicity, its polyextremophily, its association to the human environment as well as its close relation to many other black fungi. While studies looking at the transcriptome or the proteome have been released recently, their focus was limited to fungal response under pH and temperature stress (Chen et al, 2014 ; Blasi et al, 2015 ; Tesei et al, 2015 ). This is in contrast to other pathogenic fungi where transcriptomes studies of the infection are available both for the host and the pathogen (Enguita et al, 2016 ).…”

The transcriptomic and phenotypic response of the melanized yeast Exophiala dermatitidis to ionizing particle exposure

“…We are interested in the factors that mediate the response to IR in fungi, and have previously characterized how melanin affects the response of E. dermatitidis to γ-IR [31,38]. E. dermatitidis is useful for such studies, as it is genetically tractable, and due to its ability to thrive in austere environments, is a candidate for bioremediation and sensing of radionuclide contamination [39]. Acute and chronic γ-IR exposures induced dramatic transcriptomic responses in E. dermatitidis that allowed us to identify previously uncharacterized proteins important for its radiation resistance, but nothing is currently known about how these results relate to the effects that ionizing particles have on this organism.…”