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An antifungal benzimidazol reveals novel sterols after inhibition of Erg11.

ABSTRACT: Fungal infections are a serious health problem in clinics especially in the immune-compromised patient. Disease ranges from widespread superficial infections like vulvovaginal infections to life-threatening systemic candidiasis. Especially for systemic mycoses only a limited arsenal of antifungals is available. The most commonly used classes of antifungal compounds used include azoles, polyenes and echinocandines. Due to emerging resistance to standard therapy and significant side effects and high costs for several antifungals.,there is a medical need for new antifungals in the clinic and general practice. In order to expand the arsenal of compounds with antifungal activities we previously screened a compound library, using a new type of activity-selectivity (AS) assay analysing both the antifungal activity and the compatibility with human cells at the same time. One compound, ((S)-2-(1-aminoisobutyl)-1-(3-chlorobenzyl) benzimidazole (EMC120B12)), showed high antifungal activity against several species of pathogenic yeasts including C. glabrata and C. krusei, species which are highly refractory to antifungals, especially to the commonly used azoles. Here we could show by transcriptional profiling and sterol analysis that the target of this new antifungal compound is the ergosterol pathway. The effects of EMC120B12 on sterol biosynthesis mimic those of fluconazole, strongly indicating that EMC120B12 also targets ERG11 like the azols. But not only the marker sterol 14 methylergosta 8,24(28) dien 3β,6α diol accumulated in C. krusei under EMC120B12 treatment, but also hitherto unknown related sterols. The novel sterols have a 3β,6α diol structure. Furthermore, this is the first time that a benzimidazole structure has been shown to result in a block of the sterol pathway by accumulating marker sterols connected to ERG11 inactivation.

ORGANISM(S): Candida albicans Candida albicans SC5314

PROVIDER: GSE64976 | GEO | 2015/06/30

SECONDARY ACCESSION(S): PRJNA272618

REPOSITORIES: GEO

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Project description:Fungal infections are a serious health problem in clinics especially in the immune-compromised patient. Disease ranges from widespread superficial infections like vulvovaginal infections to life-threatening systemic candidiasis. Especially for systemic mycoses only a limited arsenal of antifungals is available. The most commonly used classes of antifungal compounds used include azoles, polyenes and echinocandines. Due to emerging resistance to standard therapy and significant side effects and high costs for several antifungals.,there is a medical need for new antifungals in the clinic and general practice. In order to expand the arsenal of compounds with antifungal activities we previously screened a compound library, using a new type of activity-selectivity (AS) assay analysing both the antifungal activity and the compatibility with human cells at the same time. One compound, ((S)-2-(1-aminoisobutyl)-1-(3-chlorobenzyl) benzimidazole (EMC120B12)), showed high antifungal activity against several species of pathogenic yeasts including C. glabrata and C. krusei, species which are highly refractory to antifungals, especially to the commonly used azoles. Here we could show by transcriptional profiling and sterol analysis that the target of this new antifungal compound is the ergosterol pathway. The effects of EMC120B12 on sterol biosynthesis mimic those of fluconazole, strongly indicating that EMC120B12 also targets ERG11 like the azols. But not only the marker sterol 14 methylergosta 8,24(28) dien 3β,6α diol accumulated in C. krusei under EMC120B12 treatment, but also hitherto unknown related sterols. The novel sterols have a 3β,6α diol structure. Furthermore, this is the first time that a benzimidazole structure has been shown to result in a block of the sterol pathway by accumulating marker sterols connected to ERG11 inactivation. In total, three biological replicates were performed. All experiments were performed as dye swaps. Thus, in total 18 arrays have been hybridzed. Hybridization experiments included an untreated reference sample and a sample of cells treated with either ((1S)-1-[1-(3-chlorobenzyl)-1H-benzimidazol-2-yl]-2-methylpropyl-amine) (EMC120B12), Fluconazole or Nocodazole. The array included one technical replicate of each probe.

Project description:In the pathogenic yeast Candida albicans, the zinc cluster transcription factor Upc2p has been shown to regulate expression of ERG11 and other genes involved in ergosterol biosynthesis upon exposure to azole antifungals. ERG11 encodes lanosterol demethylase, the target enzyme of this antifungal class. Over-expression of UPC2 reduces azole susceptibility, whereas its disruption results in hypersusceptibility to azoles and reduced accumulation of exogenous sterols. Constitutive up-regulation of ERG11 is a major cause of resistance to fluconazole in clinical isolates of C. albicans, yet the mechanism for this has yet to be determined. Using genome-wide gene expression profiling, we found UPC2 and other genes involved in ergosterol biosynthesis to be coordinately up-regulated with ERG11 in a fluconazole resistant clinical isolate as compared with a matched susceptible isolate from the same patient. Sequence analysis of the UPC2 alleles of these isolates revealed that the resistant isolate contained a single nucleotide substitution in one UPC2 allele that resulted in a G648D exchange in the encoded protein. Introduction of the mutated allele into a drug susceptible strain resulted in constitutive up-regulation of ERG11 and increased resistance to fluconazole. By comparing the gene expression profiles of the fluconazole resistant isolate and of strains carrying wild-type and mutated UPC2 alleles, we identified target genes that are controlled by Upc2p. Here we show for the first time that a gain-of-function mutation in UPC2 leads to increased expression of ERG11 and imparts resistance to fluconazole in clinical isolates of C. albicans. Keywords: genome-wide expression profiling Clinical isolates S1 (susceptible) and S2 (resistant), genome strain SC5314, UPC2 disruption strains (UPC2M4A and UPC2M4B), UPC2 re-integrant strains of non-mutated UPC2 allele (UPC2M2K21A and UPC2M2K21B), and UPC2 re-integrant strains of mutated UPC2 allele (UPC2M2K31A and UPC2M2K31B) were grown for 3 hours until log phase. RNA was extracted for each isolate/strain. Experiments were performed in duplicate.

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An antifungal benzimidazol reveals novel sterols after inhibition of Erg11.

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