Nitrogen source-dependent capsule induction in human pathogenic Cryptococcus species.
Ontology highlight
ABSTRACT:
ORGANISM(S): Cryptococcus neoformans
SUBMITTER: Aubrey Frazzitta
PROVIDER: E-GEOD-46829 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
Similar Datasets
Project description:Cryptococcus neoformans causes meningoencephalitis and is an increasing human health threat. C. neoformans is neurotropic, and persists in the cerebrospinal fluid (CSF) of the mammalian host during infection. In order to survive in the host, pathogenic fungi must procure nutrients such as carbon and nitrogen. To enhance our understanding of nutrient acquisition during infection by Cryptococcus species, we examined utilization of nitrogen sources available in CSF. We screened for growth and capsule production of 817 global environmental and clinical isolates on various sources of nitrogen. Capsule production was assessed using ammonium and urea in the presence or absence of benomyl to determine the relationship of urea exposure to capsule production. Since urea is metabolized to ammonia and CO2 (a known signal for capsule induction), we examined urea metabolism mutants for their response to urea regarding capsule production. Non-preferred nitrogen sources were found to greatly affect capsule production in pathogenic species of Cryptococcus. Urea induced the greatest magnitude of capsule production. Capsule induction by urea was greater in Cryptococcus gattii strains than in C. neoformans strains. In addition, both environmental and clinical strains grew robustly on uric acid, casamino acids, creatinine, and asparagine as sole nitrogen sources. While substantial growth on nitrate was not apparent at day 3, growth was apparent by day 6 for all serotypes.
2013-09-25 | GSE46829 | GEO
Project description:Ubiquitination is a reversible protein modification involved in various cellular processes in eukaryotic cells. Deubiquitinating enzymes, the proteins responsible for the removal of ubiquitin, act as essential regulators to maintain ubiquitin homeostasis and to exquisitely regulate protein degradation via the ubiquitination pathway. Cryptococcus neoformans is an important basidiomycete pathogen that causes life-threatening meningoencephalitis primarily within the immunocompromised population. In order to understand the possible influence deubiquitinating enzymes have on growth and virulence of the model pathogenic yeast Cryptococcus neoformans, we generated deletion mutants of 7 putative deubiquitinase genes. Compared to other deubiquitinating enzyme mutants, a ubp5M-bM-^HM-^F mutant exhibited severely attenuated virulence and many distinct phenotypes, including decreased capsule formation, hypomelanization, defective sporulation, and elevated sensitivity to several external stressors (such as high temperature, oxidative and nitrosative stresses, high salts, and antifungal agents). Ubp5 appears to be the major deubiquitinating enzyme in C. neoformans for maintaining a pool of free ubiquitin for stress responses, supports the evolutionary divergence of Cryptococcus sp. from the model yeast S. cerevisiae, and provides an important paradigm for understanding the potential role of deubiquitination in virulence by other pathogenic fungi. In addition, other putative deubiquitinase mutants (doa4M-bM-^HM-^F and ubp13M-bM-^HM-^F) exhibit similar phenotypes to the ubp5M-bM-^HM-^F mutant, illustrating possible functional overlap among deubiquitinating enzymes in C. neoformans. Certain functioning deubiquitinating enzymes are essential for the virulence composite of C. neoformans and provide an additional yeast survival and propagation advantage in the host. In this study, transcription profiles of ubp5 mutant and WT Cryptococcus neoformans strains were compared in a dye-swap experiment following 1hr exposure to either 30C or 37C.
2012-04-10 | E-GEOD-35067 | biostudies-arrayexpress
Project description:Ubiquitination is a reversible protein modification involved in various cellular processes in eukaryotic cells. Deubiquitinating enzymes, the proteins responsible for the removal of ubiquitin, act as essential regulators to maintain ubiquitin homeostasis and to exquisitely regulate protein degradation via the ubiquitination pathway. Cryptococcus neoformans is an important basidiomycete pathogen that causes life-threatening meningoencephalitis primarily within the immunocompromised population. In order to understand the possible influence deubiquitinating enzymes have on growth and virulence of the model pathogenic yeast Cryptococcus neoformans, we generated deletion mutants of 7 putative deubiquitinase genes. Compared to other deubiquitinating enzyme mutants, a ubp5M-bM-^HM-^F mutant exhibited severely attenuated virulence and many distinct phenotypes, including decreased capsule formation, hypomelanization, defective sporulation, and elevated sensitivity to several external stressors (such as high temperature, oxidative and nitrosative stresses, high salts, and antifungal agents). Ubp5 appears to be the major deubiquitinating enzyme in C. neoformans for maintaining a pool of free ubiquitin for stress responses, supports the evolutionary divergence of Cryptococcus sp. from the model yeast S. cerevisiae, and provides an important paradigm for understanding the potential role of deubiquitination in virulence by other pathogenic fungi. In addition, other putative deubiquitinase mutants (doa4M-bM-^HM-^F and ubp13M-bM-^HM-^F) exhibit similar phenotypes to the ubp5M-bM-^HM-^F mutant, illustrating possible functional overlap among deubiquitinating enzymes in C. neoformans. Certain functioning deubiquitinating enzymes are essential for the virulence composite of C. neoformans and provide an additional yeast survival and propagation advantage in the host. WT Cryptococcus neoformans strain H99 was incubated in pooled ex vivo human CSF obtained from de-identified patients and harvested after 24hr for RNA extraction. New Zealand White rabbits were inoculated with WT strain H99 and harvested by intracisternal spinal tap on days 1 and 7 for RNA extraction.
2012-04-10 | E-GEOD-36182 | biostudies-arrayexpress
Project description:Ubiquitination is a reversible protein modification involved in various cellular processes in eukaryotic cells. Deubiquitinating enzymes, the proteins responsible for the removal of ubiquitin, act as essential regulators to maintain ubiquitin homeostasis and to exquisitely regulate protein degradation via the ubiquitination pathway. Cryptococcus neoformans is an important basidiomycete pathogen that causes life-threatening meningoencephalitis primarily within the immunocompromised population. In order to understand the possible influence deubiquitinating enzymes have on growth and virulence of the model pathogenic yeast Cryptococcus neoformans, we generated deletion mutants of 7 putative deubiquitinase genes. Compared to other deubiquitinating enzyme mutants, a ubp5∆ mutant exhibited severely attenuated virulence and many distinct phenotypes, including decreased capsule formation, hypomelanization, defective sporulation, and elevated sensitivity to several external stressors (such as high temperature, oxidative and nitrosative stresses, high salts, and antifungal agents). Ubp5 appears to be the major deubiquitinating enzyme in C. neoformans for maintaining a pool of free ubiquitin for stress responses, supports the evolutionary divergence of Cryptococcus sp. from the model yeast S. cerevisiae, and provides an important paradigm for understanding the potential role of deubiquitination in virulence by other pathogenic fungi. In addition, other putative deubiquitinase mutants (doa4∆ and ubp13∆) exhibit similar phenotypes to the ubp5∆ mutant, illustrating possible functional overlap among deubiquitinating enzymes in C. neoformans. Certain functioning deubiquitinating enzymes are essential for the virulence composite of C. neoformans and provide an additional yeast survival and propagation advantage in the host. New Zealand White rabbits were inoculated with WT strain H99 and harvested by intracisternal spinal tap on days 1, 3, 4, and 7. For the human sample, RNA was extracted from CSF obtained from a de-identified patient with cryptococcal meningitis.
2012-04-10 | E-GEOD-36183 | biostudies-arrayexpress
Project description:Ubiquitination is a reversible protein modification involved in various cellular processes in eukaryotic cells. Deubiquitinating enzymes, the proteins responsible for the removal of ubiquitin, act as essential regulators to maintain ubiquitin homeostasis and to exquisitely regulate protein degradation via the ubiquitination pathway. Cryptococcus neoformans is an important basidiomycete pathogen that causes life-threatening meningoencephalitis primarily within the immunocompromised population. In order to understand the possible influence deubiquitinating enzymes have on growth and virulence of the model pathogenic yeast Cryptococcus neoformans, we generated deletion mutants of 7 putative deubiquitinase genes. Compared to other deubiquitinating enzyme mutants, a ubp5M-bM-^HM-^F mutant exhibited severely attenuated virulence and many distinct phenotypes, including decreased capsule formation, hypomelanization, defective sporulation, and elevated sensitivity to several external stressors (such as high temperature, oxidative and nitrosative stresses, high salts, and antifungal agents). Ubp5 appears to be the major deubiquitinating enzyme in C. neoformans for maintaining a pool of free ubiquitin for stress responses, supports the evolutionary divergence of Cryptococcus sp. from the model yeast S. cerevisiae, and provides an important paradigm for understanding the potential role of deubiquitination in virulence by other pathogenic fungi. In addition, other putative deubiquitinase mutants (doa4M-bM-^HM-^F and ubp13M-bM-^HM-^F) exhibit similar phenotypes to the ubp5M-bM-^HM-^F mutant, illustrating possible functional overlap among deubiquitinating enzymes in C. neoformans. Certain functioning deubiquitinating enzymes are essential for the virulence composite of C. neoformans and provide an additional yeast survival and propagation advantage in the host. WT strain H99, mutant strains 1A10 (ena1M-bM-^HM-^F, CNAG_00531), and 14A4 (pik1M-bM-^HM-^F, CNAG_07744) were incubated in filter-sterilized human CSF or serum from anonymous human donors at 37M-BM-0C with shaking, and harvested at either 1 or 24 hours post-resuspension in each biological fluid for RNA extraction.
2012-04-10 | E-GEOD-36181 | biostudies-arrayexpress
Project description:The opportunistic pathogen Cryptococcus neoformans causes fungal meningoencephalitis in immunocompromised individuals. In previous studies, we found that the Hap complex in this pathogen represses genes encoding mitochondrial respiratory functions and TCA cycle components under low-iron conditions. The orthologous Hap2/3/4/5 complex in Saccharomyces cerevisiae exerts a regulatory influence on mitochondrial functions and Hap4 is subject to glucose repression via the carbon catabolite repressor Mig1. In this study, we explored the regulatory link between a candidate ortholog of the Mig1 protein and the HapX component of the Hap complex in C. neoformans. This analysis revealed repression of MIG1 by HapX and activation of HAPX by Mig1 in low iron conditions, and Mig1 regulation of mitochondrial functions including respiration, tolerance for reactive oxygen species, and expression of genes for iron-consuming and iron-acquisition functions. Consistent with these regulatory functions, a mig1Î mutant had impaired growth on inhibitors of mitochondrial respiration and ROS inducers. Furthermore, deletion of MIG1 provoked a dysregulation in nutrient sensing via the TOR pathway and impacted the pathway for cell wall remodeling. Importantly, loss of Mig1 increased susceptibility to fluconazole thus further establishing a link between azole antifungal drugs and mitochondrial function. Mig1 and HapX were also required together for survival in macrophages, but Mig1 alone had a minimal impact on virulence in mice. Overall, these studies provide novel insights into a HapX/Mig1 regulatory network and reinforce an association between mitochondrial dysfunction and drug susceptibility that may provide new targets for the development of antifungal drugs. In this study, transcription profiles of WT and mig1D mutant strains of Cryptococcus neoformans were compared in a dye-swap experiment following 6hr exposure to Low Iron Medium (LIM) or LIM + 100mM FeCl3.
2015-12-17 | E-GEOD-76063 | biostudies-arrayexpress
Project description:We compared the transcriptome of subpopulations of Cryptococcus neoformans cells within the lungs and C. neoformans cells cultured in capsule repressing medium, capsule inducing medium, and capsule inducing medium with the addition of 10% conditioned medium from cells grown in capsule repressing medium. The aim of the study was to identify genes that regulate C. neoformans cell body and capsule size reductions.
2022-01-01 | GSE152784 | GEO
Project description:Cryptococcus neoformans is an opportunistic basidiomycete pathogen that is a major etiological agent of fungal meningoencephalitis leading to more than 180,000 deaths worldwide annually. For this pathogen, the polysaccharide capsule is a key virulence factor, which interferes with the phagocytosis by host innate immune cells, but its complex signaling networks remain elusive. In this study, we systematically analyzed capsule biosynthesis and signaling networks by using C. neoformans transcription factor (TF) and kinase mutant libraries under diverse capsule-inducing conditions, such as Dulbecco’s Modified Eagle’s (DME), Littman’s medium (LIT) and fetal bovine serum (FBS) medium. We found that deletion of GAT201, YAP1, BZP4, and ADA2 consistently causes capsule production defects in all tested media, indicating that they are capsule-regulating core TFs. Epistatic and expression analysis showed that Yap1 and Ada2 control Gat201 upstream, whereas Bzp4 and Gat201 regulate capsule production independently. We next searched for potential upstream kinases and found that mutants deleted of PKA1, BUD32, POS5, IRE1 or CDC2801 showed reduced capsule production under all three capsule induction conditions, whereas mutants deleted of HOG1 and IRK5 displayed enhanced capsule production. Notably, Pka1 and Irk5 controls induction of GAT201 and BZP4, respectively, under capsule induction condition. Finally, we monitored transcriptome profiles governed by Bzp4, Gat201, and Ada2 under capsule-inducing condition and demonstrated that these TFs regulate redundant and unique sets of downstream target genes. In conclusion, this study provides further insight into the complex regulatory mechanism of capsule production related signaling pathways in C. neoformans.
2022-10-18 | GSE208163 | GEO
Project description:Cryptococcus neoformans is a fungal pathogen responsible for an increased mortality among immunocompromised individuals. Long antifungal therapies to treat cryptococcal infections have compounded the occurrence of resistant strains that threaten the efficacy of current treatments. In this senseDue to resistance mechanisms, discovery of compounds that inhibit virulence factors, rather than kill the fungus, have emerged as potential new strategies to combat infection and reduce the rate of resistance due to lower selective pressure. Invertebrates rely solely on an effective innate immune system to prevent infections, provide providing a potential one health approach for discovery of novel antifungal and antibacterial compounds. Here, we demonstrate a differentiated extraction of proteins from three mollusks (freshwater and terrestrial) and evaluate extract their effects against the growth and virulence factor production (thermotolerance, melanin, capsule, and biofilm) in C. neoformans. We show that clarified extracts of Planorbella pilsbryi have a fungicidal effect on cryptococcal cells in a comparable way to Fluconazolefluconazole. Similarly, crude and clarifiedall extracts of Cipangopaludina chinensis not only affects cryptococcal thermotolerance but also impairs biofilm and capsule production. In addition, incubation of C. neoformans with clarified extracts of Cepaea nemoralis extracts reduced capsule production. Using inhibitory activity of extracts against peptidases related with virulence factors and Quantitative quantitative proteomics arose distinct proteome signatures for each extract and proposed proteins driving the observed anti-virulence properties. Overall, this work demonstratesproves the potential of compounds derived from natural sources to inhibit virulence factor production in a clinically important fungal pathogen.
2023-03-06 | PXD038987 | Pride
Project description:The RNA interference (RNAi) mediated by homology-dependent degradation of the target mRNA with small RNA molecules plays a key role in controlling transcription and translation processes in a number of eukaryotic organisms. The RNAi machinery is also evolutionarily conserved in a wide variety of fungal species, including pathogenic fungi. To elucidate the physiological functions of the RNAi pathway in Cryptococcus neoformans that causes fungal meningitis, here we performed genetic analyses for genes encoding Argonaute (AGO1 and AGO2), RdRP (RDP1), and Dicers (DCR1 and DCR2) in both serotype A and D C. neoformans. The present study shows that Ago1, Rdp1, and Dcr2 are the major components of the RNAi process occurring in C. neoformans. However, the RNAi machinery is not involved in regulation of production of two virulence factors (capsule and melanin), sexual differentiation, and diverse stress response. To further gain insights into the global regulatory circuit governed by the RNAi pathway, comparative transcriptome analysis using the serotype A and D RNAi mutants was performed. Notably, an increase in transcript abundance of active transposons, such as T2 and T3, was observed in the rdp1? mutant. Therefore, this study can improve our understanding of the role of the RNAi genes in human fungal pathogens including C. neoformans. This SuperSeries is composed of the following subset Series: GSE21176: Molecular and Functional Characterization of the role of RNA silencing components in Cryptococcus neoformans [RNAi_Serotype A] GSE21177: Molecular and Functional Characterization of the role of RNA silencing components in Cryptococcus neoformans [RNAi_Serotype D] Refer to individual Series
2010-05-01 | E-GEOD-21178 | biostudies-arrayexpress