Functional convergence of gliP and aspf1 in Aspergillus fumigatus pathogenicity

Liu, Hong; Xu, Wenjie; Solis, Norma V.; Woolford, Carol A.; Mitchell, Aaron P.; Filler, Scott G.

doi:10.1080/21505594.2018.1482182

“…We observed that Δace1infected mice survived significantly longer than mice infected with the wild-type strain or the Δace1+ace1 complemented strain. The finding that mice infected with the Δace1 mutant maintained a high pulmonary fungal burden yet had reduced mortality is similar to what has been found with A. fumigatus mutants with defects in secondary metabolite production [12,31], suggesting that Ace1 may govern the expression of secondary metabolite genes.…”

Section: Ace1 Governs Production Of Secondary Metabolites and Toxins supporting

confidence: 80%

“…Of these gene clusters, 10 had reduced mRNA expression in the Δace1 mutant, 3 had increased mRNA expression, and 3 had both increased and decreased mRNA expression. In the Δace1 mutant, there was also reduced expression of aspf1 (Afu5g02330), which encodes a ribotoxin that enhances A. fumigatus virulence [12,37] (S2 Table). We verified the low levels of aspf1 mRNA in the Δace1 mutant by qPCR ( Fig 7A).…”

Section: Ace1 Governs Production Of Secondary Metabolites and Toxins mentioning

confidence: 99%

“…Next, we investigated whether the attenuated virulence of the Δace1 mutant was due to decreased expression of aspf1, which encodes a ribotoxin [37]. Previously, we have determined that Asp f1 is required for the maximal virulence of A. fumigatus in corticosteroid treated mice [12]. We constructed a variant of the Δace1 mutant in which the expression of aspf1 was driven by the constitutive gpdA promoter ( Fig 7A).…”

Section: Ace1 Governs Virulence Via Asp F1mentioning

confidence: 99%

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DeterminingAspergillus fumigatustranscription factor expression and function during invasion of the mammalian lung

Liu¹,

Xu

²

,

Bruno

³

et al. 2020

Preprint

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To gain a better understanding of the transcriptional response of Aspergillus fumigatus during invasive pulmonary infection, we used a NanoString nCounter to assess the transcript levels of 467 A. fumigatus genes during growth in the lungs of immunosuppressed mice. These genes included ones known to respond to diverse environmental conditions and those encoding most transcription factors in the A. fumigatus genome. We found that invasive growth in vivo induces a unique transcriptional profile as the organism responds to nutrient limitation and attack by host phagocytes. This in vivo transcriptional response is largely mimicked by in vitro growth in Aspergillus minimal medium that is deficient in nitrogen, iron, and/or zinc. From the transcriptional profiling data, we selected 9 transcription factor genes that were either highly expressed or strongly up-regulated during in vivo growth. Deletion mutants were constructed for each of these genes and assessed for virulence in mice. Two transcription factor genes were found to be required for maximal virulence. One was rlmA, which governs the ability of the organism to proliferate in the lung. The other was ace1, which regulates of the expression of multiple secondary metabolite gene clusters and mycotoxin genes independently of laeA. Using deletion and overexpression mutants, we determined that the attenuated virulence of the Δace1 mutant is due to decreased expression aspf1, which specifies a ribotoxin, but is not mediated by reduced expression of the fumigaclavine gene cluster or the fumagillin-pseruotin supercluster. Thus, in vivo transcriptional profiling focused on transcription factors genes provides a facile approach to identifying novel virulence regulators.Author summaryAlthough A. fumigatus causes the majority of cases of invasive aspergillosis, the function of most of the genes in its genome remains unknown. To identify genes encoding transcription factors that may be important for virulence, we used a NanoString nCounter to measure the mRNA levels of A. fumigatus transcription factor genes in the lungs of mice with invasive aspergillosis. The transcriptional profiling data indicate that the organism is exposed to nutrient limitation and stress during growth in the lungs, and that it responds by up-regulating genes that encode mycotoxins and secondary metabolites. In vitro, this response was most closely mimicked by growth in medium that was deficient in nitrogen, iron and/or zinc. Using the transcriptional profiling data, we identified two transcription factors that govern A. fumigatus virulence. These were RlmA, which is governs proliferation in the lung and Ace1, which controls the production of mycotoxins and secondary metabolites.

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“…Here, we have described two new hyperactive alleles of atrR and wanted to determine what impact these would have on virulence in this murine model. We used a lung inhalation model ( 25 ) to test the impact of loss of a key AtrR target gene, the ABC transporter-encoding abcG1 locus, or overproduction of AtrR itself ( hspA-atrR ) on fungal virulence. Mice were challenged with these strains along with an isogenic wild-type control and survival followed over an 11-day time course ( Fig.…”

Section: Resultsmentioning

confidence: 99%

AtrR Is an Essential Determinant of Azole Resistance in Aspergillus fumigatus

Paul

¹

,

Stamnes

²

,

Thomas

³

et al. 2019

mBio

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Aspergillosis associated with azole-resistant Aspergillus fumigatus has a mortality rate that can approach 90% in certain patient populations. The best-understood avenue for azole resistance involves changes in the cyp51A gene that encodes the target of azole drugs, lanosterol α-14 demethylase. The most common azole resistance allele currently described is a linked change corresponding to a change in the coding sequence of cyp51A and a duplication of a 34-bp region in the promoter leading to a tandem repeat (TR). Our previous studies identified a positively acting transcription factor called AtrR that binds to the promoter of cyp51A as well as that of an important membrane transporter protein gene called abcG1. In this work, we characterize two different mutant alleles of atrR, either an overproducing or an epitope-tagged form, causing constitutive activation of this factor. Using an epitope-tagged allele of atrR for chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-seq), the genomic binding sites for AtrR were determined. Close to 900 genes were found to have an AtrR response element (ATRE) in their promoter regions. Transcriptome evaluation by RNA sequencing (RNA-seq) indicated that both alleles led to elevated transcription of a subset of target genes. An electrophoretic mobility shift assay and DNase I protection mapping localized the ATREs in both the abcG1 and cyp51A promoters. The ATRE in cyp51A was located within the 34-bp repeat element. Virulence in a murine model was compromised when AtrR was either deleted or overproduced, indicating that the proper dosage of this factor is key for pathogenesis. IMPORTANCE Aspergillus fumigatus is the major filamentous fungal pathogen in humans. Infections associated with A. fumigatus are often treated with azole drugs, but resistance to these antifungal agents is increasing. Mortality from aspergillosis associated with azole-resistant fungi is extremely high. Previous work has identified transcriptional control of the azole drug target-encoding gene cyp51A as an important contributor to resistance in A. fumigatus. Here, we demonstrate that the transcription factor AtrR binds to a region in the cyp51A promoter that is associated with alleles of this gene conferring clinically important azole resistance. Using high-throughput genomic technologies, we also uncover a large suite of target genes controlled by AtrR. These data indicate that AtrR coordinately regulates many different processes involved in drug resistance, metabolism, and virulence. Our new understanding of AtrR function provides important new insight into the pathogenesis of A. fumigatus.

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“…To determine the transcriptional response of A. fumigatus during invasive infection, we developed two NanoString probesets. The first was a pilot set that contained probes for 97 genes with functional annotations that included metabolism, iron acquisition, hypoxia, cell wall, and stress response, as described previously [11,12]. The second contained probes for 400 genes that specify virtually all predicted transcription factors in the A. fumigatus genome.…”

Section: Invasive Infection Induces Expression Of Genes Involved In Nmentioning

confidence: 99%

Determining Aspergillus fumigatus transcription factor expression and function during invasion of the mammalian lung

Liu

¹

,

Xu

²

,

Bruno

³

et al. 2021

Self Cite

View full text Add to dashboard Cite

To gain a better understanding of the transcriptional response of Aspergillus fumigatus during invasive pulmonary infection, we used a NanoString nCounter to assess the transcript levels of 467 A. fumigatus genes during growth in the lungs of immunosuppressed mice. These genes included ones known to respond to diverse environmental conditions and those encoding most transcription factors in the A. fumigatus genome. We found that invasive growth in vivo induces a unique transcriptional profile as the organism responds to nutrient limitation and attack by host phagocytes. This in vivo transcriptional response is largely mimicked by in vitro growth in Aspergillus minimal medium that is deficient in nitrogen, iron, and/or zinc. From the transcriptional profiling data, we selected 9 transcription factor genes that were either highly expressed or strongly up-regulated during in vivo growth. Deletion mutants were constructed for each of these genes and assessed for virulence in mice. Two transcription factor genes were found to be required for maximal virulence. One was rlmA, which is required for the organism to achieve maximal fungal burden in the lung. The other was sltA, which regulates of the expression of multiple secondary metabolite gene clusters and mycotoxin genes independently of laeA. Using deletion and overexpression mutants, we determined that the attenuated virulence of the ΔsltA mutant is due in part to decreased expression aspf1, which specifies a ribotoxin, but is not mediated by reduced expression of the fumigaclavine gene cluster or the fumagillin-pseruotin supercluster. Thus, in vivo transcriptional profiling focused on transcription factors genes provides a facile approach to identifying novel virulence regulators.

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Functional convergence of gliP and aspf1 in Aspergillus fumigatus pathogenicity

Cited by 14 publications

References 53 publications

DeterminingAspergillus fumigatustranscription factor expression and function during invasion of the mammalian lung

DeterminingAspergillus fumigatustranscription factor expression and function during invasion of the mammalian lung

AtrR Is an Essential Determinant of Azole Resistance in Aspergillus fumigatus

Determining Aspergillus fumigatus transcription factor expression and function during invasion of the mammalian lung

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