Transcriptome-wide interrogation of the posaconazole-induced stress response of Rhizopus delemar and Mucor circinelloides

Author:

Laura A Doorley (US)

Abstract:

Objectives:
Mucormycosis is an aggressive and life-threatening fungal infection, particularly among immunocompromised patients. Posaconazole, one of few antifungal treatments effective against mucormycetes, is essential to both front-line and salvage therapies. To further our understanding of the posaconazole-induced stress response of Mucoralean molds, we describe the transcriptional response of the two most common causative species, Mucor circinelloides and Rhizopus delemar, to posaconazole exposure in-vitro.
Methods:
R. delemar (ATCC 56536), and M. circinelloides (ATCC 38592) were grown to establish filamentation in RPMI liquid media and subsequently supplemented with DMSO or 2g/mL posaconazole in biological triplicate. Cultures were then incubated for either 1 or 4 hours prior to washing, liquid nitrogen crush, and RNA extraction. Transcriptional profiling by RNA-sequencing was performed and analyzed for differential expression and gene ontology (GO) term enrichment as compared to DMSO controls.
Results:
R. delemar differentially expressed 723 and 963 genes following 1 hour and 4 hours of posaconazole exposure, respectively, and of these, 409 were shared between the time points. M. circinelloides differentially expressed 757 and 562 genes following 1 hour and 4 hours of posaconazole exposure, respectively, of which, 258 were shared between the two time points. Analysis of GO-process annotations only identified transmembrane transport as enriched among the differentially expressed genes at 1 and 4 hours for both organisms (FDR p-value < 0.05) and multiple major facilitator superfamily transporters displayed similar expression patterns across both time points in both organisms. Interestingly, for both organisms there were two homologous zinc-finger transcription factors that were differentially expressed across both time points, with one commonly up-regulated and one commonly down-regulated (>2-fold, FDR 0.05) following posaconazole exposure.Intriguingly, relatively fewer predicted ergosterol biosynthesis genes exhibited increased expression (>2-fold, FDR 0.05) following posaconazole treatment in R. delemar versus M. circinelloides at either time point (8 versus 18 genes). Moreover, M. circinelloides exhibited increased expression of both Cyp51 paralogs whereas R. delemar only had one Cyp51-encoding gene induced by posaconazole exposure.
Conclusions:
Posaconazole is a key antifungal agent commonly relied upon in the treatment of patients with mucormycosis. To our knowledge, this work is the first transcriptome-wide interrogation of the posaconazole-induced stress response in Rhizopus and Mucor. This study advances our understanding of how agents of mucormycosis respond to posaconazole-induced stress, highlighting both a shared set of transcriptionally responsive genes in Mucor and Rhizopus and providing greater detail of the organism-specific transcriptional responses for the two predominating agents of mucormycosis.

Abstract Number: 15

Conference Year: 2024

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