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Remodeling of global transcription patterns of C. neoformans genes mediated by stress-activated HOG signaling pathways

ABSTRACT: The ability to sense and adapt to a hostile host environment is a crucial element for virulence of pathogenic fungi, including Cryptococcus neoformans. These cellular responses are evoked by diverse signaling cascades, including the stress-activated HOG pathway. Despite previous analysis of central components of the HOG pathway, its downstream signaling network is poorly characterized in C. neoformans. Here we performed comparative transcriptome analysis with HOG signaling mutants to explore stress-regulated genes and their correlation with the HOG pathway in C. neoformans. In this study we not only provide important insights into remodeling patterns of global gene expression for counteracting external stresses, but also elucidated novel characteristics of the HOG pathway in C. neoformans. First, inhibition of the HOG pathway increases expression of ergosterol biosynthesis genes and cellular ergosterol content, conferring a striking synergistic antifungal activity with amphotericin B and providing an excellent opportunity to develop a novel therapeutic method for treatment of cryptococcosis. Second, a number of cadmium-sensitive genes are differentially regulated by the HOG pathway, and their mutation causes resistance to cadmium. Finally, we have discovered novel stress-defense and HOG-dependent genes, which encodes a sodium/potassium efflux pump, protein kinase, multidrug transporter system, and elements of the ubiquitin-dependent system.

ORGANISM(S): Cryptococcus neoformans var. neoformans JEC21 Cryptococcus neoformans var. grubii

PROVIDER: GSE16692 | GEO | 2009/06/27

SECONDARY ACCESSION(S): PRJNA117373

REPOSITORIES: GEO

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Project description:The ability to sense and adapt to a hostile host environment is a crucial element for virulence of pathogenic fungi, including Cryptococcus neoformans. These cellular responses are evoked by diverse signaling cascades, including the stress-activated HOG pathway. Despite previous analysis of central components of the HOG pathway, its downstream signaling network is poorly characterized in C. neoformans. Here we performed comparative transcriptome analysis with HOG signaling mutants to explore stress-regulated genes and their correlation with the HOG pathway in C. neoformans. In this study we not only provide important insights into remodeling patterns of global gene expression for counteracting external stresses, but also elucidated novel characteristics of the HOG pathway in C. neoformans. First, inhibition of the HOG pathway increases expression of ergosterol biosynthesis genes and cellular ergosterol content, conferring a striking synergistic antifungal activity with amphotericin B and providing an excellent opportunity to develop a novel therapeutic method for treatment of cryptococcosis. Second, a number of cadmium-sensitive genes are differentially regulated by the HOG pathway, and their mutation causes resistance to cadmium. Finally, we have discovered novel stress-defense and HOG-dependent genes, which encodes a sodium/potassium efflux pump, protein kinase, multidrug transporter system, and elements of the ubiquitin-dependent system. There is more than 95% genome homology between JEC21 (Cryptococcus neoformans var. neoformans serotype D) and H99 (Cryptococcus neoformans var. grubii serotype A). Therefore, 100 slides of JEC21 70-mer oligo arrays are used in this analysis. 3 biological replicate experiments are performed. Total RNAs are extracted under 3 conditions (1M NaCl, 20ug/ul Fludioxonil, 2.5mM Hydrogen peroxide) at 3 time points (0time, 30min, 60min) with 4 strains from H99 (wild type, hog1Î , ssk1Î , skn7Î). We use a mix of all the total RNAs from this experiment as the control RNA. We use Cy5 as the sample dye and Cy3 as the control dye. Several samples are dye swapped.

Project description:The high osmolarity glycerol response (HOG) pathway plays a pivotal role in the stress response, virulence regulation, and differentiation of fungi, including Cryptococcus neoformans that causes fatal meningoencephalitis. Core signaling components of in the HOG pathway, including the Tco-Ypd1-Ssk1 phosphorelay system and the Ssk2-Pbs2-Hog1 MAPK module, have been elucidated but its downstream transcription factors remain unclear. Here we demonstrated that Atf1 with a basic leucine zipper domain is the transcription factor downstream of Hog1 in C. neoformans. We found that ATF1 expression was differentially regulated by oxidative damaging agents, mainly in a Hog1-dependent, but Mpk1-independent, manner. Interestingly, Atf1 not only promoted oxidative stress response and adaptation, but also played an opposing role to Hog1 in the process. Atf1 primarily localized to the nucleus under both unstressed and oxidative stress conditions in a Hog1-independent manner. Our data demonstrated that Atf1 promoted pheromone production and sexual differentiation under negative control by Hog1. Finally, a DNA microarray-based transcriptome analysis of the atf1M-bM-^HM-^F mutant under unstressed and oxidative stress conditions revealed that Atf1 regulated oxidative stress response genes, including a sulfiredoxin gene (SRX1). Intriguing, the array data further demonstrated that Atf1 modulated basal expression of genes involved in DNA repair and genotoxic stress response. Supporting this, we found that the atf1M-bM-^HM-^F mutant was highly sensitive to genotoxic agents. In conclusion, this study provided a further insight into the Hog1-dependent oxidative and genotoxic stress response and differentiation mechanism of C. neoformans. There are more than 95% of genome homology between JEC21 and H99. Therefore 6 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 2 conditions (with or without treatment of Hydroten peroxide) from H99 (H99 Wild type strain (Cryptococcus neoformans var. grubii serotype A), and atf1M-NM-^T). We use the mixed all of total RNAs from this experiment as a control RNA. We use Cy3 as Sample dye and Cy5 as a control dye.

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.

Project description:A family of APSES transcription factor is known to be fungal-specific transcriptional regulators and play important roles in governing growth, differentiation, and virulence of diverse fungal pathogens. Yet none of APSES-like transcription factors have been identified and investigated in a basidiomycetous fungal pathogen, Cryptococcus neoformans. In the present study we discovered an APSES-like transcription factor, mbs1 (Mbp1/Swi4-like APSES protein 1), as one of novel flucytosine-responsive genes (total 194 genes) identified through comparative transcriptome analysis of C. neoformans hybrid sensor kinase mutants, tco1 and tco2 mutants, which displayed differential flucytosine-susceptibility. Supporting the microarray data, Northern blot and quantitative RT-PCR analysis confirmed that expression of mbs1 is rapidly induced in response to flucytosine in the wild-type strain, but not in the tco1 and tco2 mutants. Furthermore, C. neoformans with deletion of the mbs1 gene exhibited increased susceptibility to flucytosine. Intriguingly, mbs1 plays pleiotropic roles in diverse cellular process of C. neoformans. mbs1 positively regulates ergosterol biosynthesis and thereby its inhibition confers increased susceptibility and resistance to amphotericin B and azole drugs, respectively. mbs1 is also involved in DNA damage repair counteracting genotoxic stresses. During sexual differentiation mbs1 represses pheromone production, but promotes cell-cell fusion. Furthermore mbs1 is required for production of antioxidant melanin pigment and full virulence of C. neoformans. Finally we also performed DNA microarrray analysis to identify mbs1-regulated genes in C. neoformans. A majority of them were found to be involved in cell cycle regulation and DNA repair. Therefore, this study provides a novel antifungal therapeutic method for treatment of cryptococcosis. total RNAs are extracted 2 strains from H99 (H99 Wild type strain (Cryptococcus neoformans var. grubii serotype A), mbs1Δ), 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.

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Remodeling of global transcription patterns of C. neoformans genes mediated by stress-activated HOG signaling pathways

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