Transcriptome analysis of cryptococcal IPK mutants
ABSTRACT: In eukaryotes, inositol polyphosphates perform essential metabolic and signaling functions. Using human fungal pathogen Cryptococcus neoformans as a model, we created mutants in three inositol polyphosphates kinases: Arg1, Ipk1 and Kcs1. Each of the mutants produces a unique repertoire of inositol polyphosphates, different from the wild type strain. Comparative phenotypic and transcriptome analyses of wild type and mutant strains indicates that inositol polyphosphate PP-IP5 (IP7) is the key regulator of gene expression, fitness and virulence in C. neoformans. Comparison of WT and mutants (Darg1, Dkcs1 and Dipk1) grown in broth culture in the absence of stress.
Project description:Transcriptome profiling of wild type and cfo1 mutant with fluconazole treatment in Cryptococcus neoformans var. grubii H99 Purpose: The goals of this study are to compare cfo1 mutant transcriptome profiling (RNA-seq) to wild-type with or without fluconazole treatment in Cryptococcus neoformans var. grubii H99. Methods: mRNA profiles of wild-type and cfo1 mutant with or without fluconazole treatment were generated by RNA-Seq, using Illumina GAIIx. The sequence reads that passed quality filters were mapped to reference genome and the normalized RPKM values were calculated by CLC Genomics Workbench. Results: Compared to wild-type, a number of genes were differentially expressed in the cfo1 mutant, especially genes involved in iron homeostasis and transport, ergosterol biosynthesis, mitochondrial function and respiration. Conclusions: Our data suggested reduced expression of the genes in the respiratory chain is the main reason for altered antifungal sensitivity of the cfo1 mutant. The results of our study revealed that iron uptake plays a key role in fluconazole sensitivity of C. neoformans. mRNA profiles of wild-type and cfo1 mutant with fluconazole treatment were generated by RNA-Seq, using Illumina GAIIx.
Project description:Purpose: The purpose of this study is to define the mechanism of antifungal action of the vanillin derivative, o-vanillin, against Cryptococcus neoformans Methods: mRNA profiles of C. neoformasn cells cultured with or without o-vanillin were generated by RNA-Seq, using Illumina GAIIx. The sequence reads that passed quality filters were mapped to reference genome and the normalized RPKM values were calculated by CLC Genomics Workbench. Results: o-vanillin significantly altered global transcript profiles, induces oxidative stress, and interferes mitochondrial functions in C. neoformans. Conclusions: o-vanillin can be considered as the effective antifungal drug candidate. mRNA profiles of the cells grown in the presence or absence of o-vanillin were generated by RNA-Seq using Illumina GAIIx.
Project description:BACKGROUND: Lithospermum erythrorhizon, popularly known as Gromwell, is a perennial herb belonging to the family of Boraginaceae and its extract is known to have diverse pharmacological, cosmetic, and nutritional values for human. Nevertheless the biological influence of Gromwell extract on general physiology of eukaryotic cells remains unknown. In this study, we for the first time performed a global transcriptome analysis by using DNA microarray analysis to identify genes affected by the addition of Gromwell extract (GE) by using a eukaryotic microorganism, basidiomycete fungus Cryptococcus neoformans, as a model system. RESULTS: The transcriptome analysis revealed that a total of 1932 genes are differentially regulated in a statistically significant manner and expressions of 715 genes are up- (315 genes) or down-regulated (457 genes) more than twofold upon GE treatment. In response to GE treatment, genes involved in signal transduction genes are immediately regulated and the evolutionarily conserved set of genes involved in the core cellular functions, including DNA replication, RNA transcription/processing, and protein translation/processing, are generally upregulated. In contrast, a number of genes involved in carbohydrate metabolism and transport, inorganic ion transport and metabolism, post-translational modification/protein turnover/chaperone functions, and signal transduction are downregulated by the GE treatment. Among the GE-responsive genes that are also evolutionarily conserved in the human genome, we confirmed expression patterns of YSA1, TPO2, FET5 (CFO1), and PZF1 by Northern blot analysis. Based on the functional characterization of some GE-responsive genes through phenotypic analysis of gene knockout mutants, we found that GE treatment may promote cellular tolerance against a variety of environmental stresses in eukaryotes. CONCLUSIONS: A significant portion of the Cryptococcus genome is affected in expression levels by treatment of GE, implying that the general physiology of eukaryotic cells is significantly affected by the GE treatment. 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 from H99 (H99 Wild type strain (Cryptococcus neoformans var. grubii serotype A)) with 6.4 mg/ml Gromwell extract in 0, 10, 30, 60 min. 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:Purpose: To explore the function of VIB1 in regulating cellulase production in Neurospora crassa. Method: mRNA from vib-1 mutants were collected after a culture shift from sucrose to Avicel (crystaline cellulose) or carbon-free media. Expression profiles of vib-1 mutants were compared with published profiles of wild type created under the same conditions. Results: We found that many genes that specifically upregulated in wild type upon exposure to Avicel were expressed at low levels in ∆vib-1 and many other genes involved in metabolism and energy were expressed at high levels compared to wild type. Conclusions: Our study shows that VIB1 is required for suppression of glucose response and carbon catabolite repression to allow proper expression of clr-2 and subsequent cellulase production in response to cellulosic induction. Biological triplicates of liquid culture N. crassa were harvested at 4 hours after a switch from sucrose media to media of interest. Global mRNA abundances were measured by sequencing on the Illumina Genome Analyzer Iix and HiSeq2000 platforms.
Project description:Cryptococcus neoformans is an AIDS-associated human fungal pathogen and the most common cause of fungal meningitis, with a mortality rate over 40% in AIDS patients. Significant advances have been achieved in understanding its disease mechanisms. Yet the underlying mechanism of a high frequency of cryptococcal meningitis remains unclear. The existence of high inositol concentrations in brain and our earlier discovery of a large inositol transporter (ITR) gene family in C. neoformans led us to investigate the potential role of inositol in Cryptococcus-host interactions. In this study, we focus on functional analyses of two major ITR genes to understand their role in virulence of C. neoformans. Our results show that ITR1A and ITR3C are the only two ITR genes among 10 candidates that can complement the growth defect of a Saccharomyces cerevisiae strain lacking inositol transporters. Both S. cerevisiae strains heterologously expressing ITR1A or ITR3C showed high inositol uptake activity, an indication that they are major inositol transporters. Significantly, itr1a itr3c double mutants showed significant virulence attenuation in murine infection models. Mutating both ITR1A and ITR3C in an ino1 mutant background activates the expression of several remaining ITR candidates and does not show more severe virulence attenuation, suggesting that both inositol uptake and biosynthetic pathways are important for inositol acquisition. Overall, our study provides evidence that host inositol and fungal inositol transporters are important for Cryptococcus pathogenicity.
Project description:Phospholipase C (PLC) of Cryptococcus neoformans (CnPlc1) is crucial for virulence of this fungal pathogen. To investigate the mechanism of CnPlc1-mediated signaling, we established that phosphatidylinositol 4,5-bisphosphate (PIP(2)) is a major CnPlc1 substrate, which is hydrolyzed to produce inositol trisphosphate (IP(3)). In Saccharomyces cerevisiae, Plc1-derived IP(3) is a substrate for the inositol polyphosphate kinase Arg82, which converts IP(3) to more complex inositol polyphosphates. In this study, we show that in C. neoformans, the enzyme encoded by ARG1 is the major IP(3) kinase, and we further demonstrate that catalytic activity of Arg1 is essential for cellular homeostasis and virulence in the Galleria mellonella infection model. IP(3) content was reduced in the Cn?plc1 mutant and markedly increased in the Cn?arg1 mutant, while PIP(2) was increased in both mutants. The Cn?plc1 and Cn?arg1 mutants shared significant phenotypic similarity, including impaired thermotolerance, compromised cell walls, reduced capsule production and melanization, defective cell separation, and the inability to form mating filaments. In contrast to the S. cerevisiae ARG82 deletion mutant (Sc?arg82) strain, the Cn?arg1 mutant exhibited dramatically enlarged vacuoles indicative of excessive vacuolar fusion. In mammalian cells, PLC-derived IP(3) causes Ca(2+) release and calcineurin activation. Our data show that, unlike mammalian PLCs, CnPlc1 does not contribute significantly to calcineurin activation. Collectively, our findings provide the first evidence that the inositol polyphosphate anabolic pathway is essential for virulence of C. neoformans and further show that production of IP(3) as a precursor for synthesis of more complex inositol polyphosphates is the key biochemical function of CnPlc1.
Project description:Cryptococcus neoformans is the most common cause of deadly fungal meningitis. This fungus has a complex inositol acquisition and utilization system, and our previous studies have shown the importance of inositol utilization in cryptococcal development and virulence. However, how inositol utilization is regulated in this fungus remains unknown. In this study, we found that inositol, irrespective of the presence of glucose in the media, represses the expression of C. neoformans genes involved in inositol pyrophosphate biosynthesis, including the gene encoding inositol hexakisphosphate kinase Kcs1. Kcs1 was recently reported to regulate inositol metabolism in Saccharomyces cerevisiae and to impact virulence in C. neoformans. To examine the potential role of Kcs1 in inositol regulation in C. neoformans, we generated the kcs1Δ mutant and compared its phenotype with the wild type strain. We found that Kcs1 negatively regulates inositol uptake and catabolism in C. neoformans, but, in contrast to Kcs1 function in S. cerevisiae, does not appear to regulate inositol biosynthesis. Together, these results show that Kcs1 functions to fine-tune inositol acquisition to maintain inositol homeostasis in C. neoformans.
Project description:Inositol is a key cellular metabolite for many organisms. Cryptococcus neoformans is an opportunistic pathogen which primarily infects the central nervous system, a region of high inositol concentration, of immunocompromised individuals. Through the use of myo-inositol oxygenase C. neoformans can catabolize inositol as a sole carbon source to support growth and viability.Three myo-inositol oxygenase gene sequences were identified in the C. neoformans genome. Differential regulation was suggested by computational analyses of the three gene sequences. This included examination of the upstream regulatory regions, identifying ORE/TonE and UASINO sequences, conserved introns/exons, and in frame termination sequences. Homology modeling of the proteins encoded by these genes revealed key differences in the myo-inositol active site.The results suggest there are two functional copies of the myo-inositol oxygenase gene in the C. neoformans genome. The functional genes are differentially expressed in response to environmental inositol concentrations. Both the upstream regulatory regions of the genes and the structure of the specific proteins suggest that MIOX1 would function when inositol concentrations are low, whereas MIOX2 would function when inositol concentrations are high.
Project description:Cryptococcus neoformans is a fungal pathogen of immunocompromised people that causes fatal meningitis. The fungal cell wall is essential to viability and pathogenesis of C. neoformans, and biosynthesis and repair of the wall is primarily controlled by the cell wall integrity (CWI) signaling pathway. Previous work by us and others have shown that deletion of genes encoding the four major kinases in the CWI signaling pathway, namely PKC1, BCK1, MKK2 and MPK1 results in severe cell wall phenotypes, sensitivity to a variety of cell wall stressors and, for Mpk1, reduced virulence in a mouse model. Here, we examined the global transcriptional response of gene deletions of BCK1, MKK2 and MPK1 compared to wild-type cells. We found over 1000 genes were differentially expressed in one or more of the deletion strains, with 115 genes differentially expressed in all three strains, many of which have been identified as genes regulated by the cAMP/protein kinase A (PKA) pathway. Biochemical measurements of cAMP levels in the kinase deletion stains revealed significantly less cAMP in all of the deletion strains compared to wild-type cells. The deletion strains also produced significantly smaller capsules than wild type KN99 under capsule inducing conditions, although they shed similar levels of capsule as wild type. Finally, addition of exogenous cAMP led to reduced sensitivity to cell wall stress and restored surface capsule to near wild-type levels. Thus, we have direct evidence of cross talk between the CWI and cAMP/PKA pathways that may have important implications for regulation of cell wall and capsule homeostasis. Comparison of three gene deletion strains to wild-type, with 3 biological replicates for each sample.
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), ras1Δ, aca1Δ, gpa1Δ, cac1Δ, pka1Δpka2Δ), 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.