Dataset Information

Roles for Stress Response and Cell Wall Biosynthesis Pathways in Caspofungin Tolerance in Cryptococcus neoformans.

ABSTRACT: Limited antifungal diversity and availability are growing problems for the treatment of fungal infections in the face of increasing drug resistance. The echinocandins, one of the newest classes of antifungal drugs, inhibit production of a crucial cell wall component. However, these compounds do not effectively inhibit the growth of the opportunistic fungal pathogen Cryptococcus neoformans, despite potent inhibition of the target enzyme in vitro Therefore, we performed a forward genetic screen to identify cellular processes that mediate the relative tolerance of this organism to the echinocandin drug caspofungin. Through these studies, we identified 14 genetic mutants that enhance caspofungin antifungal activity. Rather than directly affecting caspofungin antifungal activity, these mutations seem to prevent the activation of various stress-induced compensatory cellular processes. For example, the pfa4? mutant has defects in the palmitoylation and localization of many of its target proteins, including the Ras1 GTPase and the Chs3 chitin synthase, which are both required for caspofungin tolerance. Similarly, we have confirmed the link between caspofungin treatment and calcineurin signaling in this organism, but we suggest a deeper mechanism in which caspofungin tolerance is mediated by multiple pathways downstream of calcineurin function. In summary, we describe here several pathways in C. neoformans that contribute to the complex caspofungin tolerance phenotype in this organism.

SUBMITTER: Pianalto KM

PROVIDER: S-EPMC6727808 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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Roles for Stress Response and Cell Wall Biosynthesis Pathways in Caspofungin Tolerance in Cryptococcus neoformans.

Pianalto Kaila M KM Billmyre R Blake RB Telzrow Calla L CL Alspaugh J Andrew JA

Genetics 20190702 1

Limited antifungal diversity and availability are growing problems for the treatment of fungal infections in the face of increasing drug resistance. The echinocandins, one of the newest classes of antifungal drugs, inhibit production of a crucial cell wall component. However, these compounds do not effectively inhibit the growth of the opportunistic fungal pathogen Cryptococcus neoformans, despite potent inhibition of the target enzyme in vitro Therefore, we performed a forward gen ...[more]

PMID: 31266771

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Project description:The cAMP-pathway plays a central role in regulation of growth, differentiation, and virulence of human pathogenic fungi, including Cryptococcus neoformans. Three major upstream signaling regulators of the adenylyl cyclase (Cac1), Ras, Aca1 (Adenylyl cyclase-associated protein 1) and G-alpha subunit protein (Gpa1), have been identified to control the cAMP-pathway in C. neoformans, but their functional relationship remains elusive. Here we performed genome-wide transcriptome analysis with C. neoformans ras1, gpa1, cac1, aca1, and pka1 pka2 mutants by DNA microarray. The aca1, gpa1, cac1, and pka1 pka2 mutants displayed similar transcriptome patterns to each other whereas the ras1 mutant exhibited distinctive transcriptome patterns compared to WT and the cAMP mutants. Interestingly, a number of environmental stress response genes are differentially modulated in the ras1 and cAMP mutants. In fact, the Ras1-signaling pathway was found to be involved in osmotic and genotoxic stress response, and maintenance of cell wall integrity via the Cdc24-dependent signaling pathway. Through this microarray analysis, we have identified a number of cAMP-dependent genes, including GRE2, HSP12, ENA1, TCO2, PKP2, CAT1, in C. neoformans. Notably, a majority of ergosterol biosynthesis genes were found to be upregulated in the cAMP mutants. Interestingly, the gpa1, cac1, and pka1 mutants, but not the aca1 and pka2 mutants were hypersensitive to amphotericin B, but resistant to fluconazole. In conclusion, we demonstrated in this study that the Ras1- and cAMP-signaling pathways are involved in stress response and sterol biosynthesis of C. neoformans. There are more than 95% of genome homology between JEC21 and H99. Therefore 100 slides of JEC21 (cryptococcus neoformans var. neoformans serotype D) 70-mer oligo are used in this analysis, 3 biological replicate experiments are performed, total RNAs are extracted with 6 strains from H99 (H99 Wild type strain (Cryptococcus neoformans var. grubii serotype A), ras1Î, aca1Î, gpa1Î, cac1Î, pka1Îpka2Î), We use the mixed all of total RNAs from this experiment as a control RNA. We use Cy5 as Sample dye and Cy3 as a control dye. several sample are dye swaped.

Dataset Information

Roles for Stress Response and Cell Wall Biosynthesis Pathways in Caspofungin Tolerance in Cryptococcus neoformans.

Publications

Roles for Stress Response and Cell Wall Biosynthesis Pathways in Caspofungin Tolerance in <i>Cryptococcus neoformans</i>.

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