Mehlem, R. T. | bioRxiv Science

bioRxiv2026

Thermal adaptation crosstalk with azole response through lncRNA in Aspergillus fumigatus

Fungal pathogens are adapting to increased temperatures altering host-pathogen interactions, disease patterns, and response to the antimicrobial drugs. Here, we show that thermal adaptation to 42{degrees}C leads to reversible changes in fungal colony size and azole drug response in the human pathogenic fungus Aspergillus fumigatus. Importantly, this adaptation is mediated by the lncRNA, afu-182, whose RNA levels negatively correlate with temperature. Growth at a lower temperature or ectopic upregulation of afu-182 RNA levels reverses the temperature adaptation. Previously, we have shown that {Delta}afu-182 strains produce worse disease outcomes in a murine model of invasive pulmonary aspergillosis (IPA). Here, more importantly, we show that the overexpression of afu-182 in clinically azole-resistant isolates increased survival in a murine model of IPA. Taken together, fungal adaptation to increased temperature leads to a decrease in afu-182 RNA levels that is associated with worse disease outcomes upon azole treatment. This provides a framework to take temperature into account when analyzing the rise in azole MIC in environmental and clinical isolates.

microbiology↗

bioRxiv2025

A long non-coding RNA regulates triazole antifungal susceptibility and virulence in Aspergillus fumigatus

Azole-resistant Aspergillus infections are a source of increasing concern with limited alternative therapeutic options. However, as most infections are still caused by azole-susceptible Aspergillus strains, there is a need to better understand fungal responses to azole antifungals. To this end, we discover that a long non-coding RNA, afu-182, is a major regulator of cyp51-independent sub-MIC azole response. We observe that loss of afu-182 leads to increased surface attached growth and poor treated disease outcomes in a murine model of invasive pulmonary aspergillosis upon azole treatment. In contrast, overexpression of afu-182 significantly reduces fungal burden in animals treated with the azole drug, posaconazole. Importantly, afu-182 levels decrease upon azole exposure and in an azole adaptation experiment, continuous exposure to low dose azole led to MIC increase in an afu-182 dependent manner. Whole transcriptome analyses revealed that azole drug treatment leads to an increase in transcripts of genes encoding 7-transmembrane domain proteins of the RTA1 family, and these proteins are negatively regulated by afu-182. Two RTA1 family genes have individual and combined effects and are sufficient to increase fungal susceptibility to azole drugs in the WT strain. Taken together, our data show a role of the long non-coding RNA afu-182 in regulating Aspergillus fumigatus response to azole drugs both in vitro and in vivo. ImportanceDrug resistance in Aspergillus is a major challenge that is often associated with the agricultural use of azoles in the environment. How drug resistance arises in vivo is still an active area of research. Here, we show that azole exposure results in fungal adaptation by lowering the RNA levels of lncRNA, which upon low dose azole exposure leads to an increase in azole drug MIC.

molecular biology↗