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Landscape of gene expression variation of natural isolates of Cryptococcus neoformans in response to biologically relevant stresses

ABSTRACT: Cryptococcus neoformans is an opportunistic environmental fungal pathogen that at its peak epidemic levels caused an estimated million cases of cryptococcal meningitis per year worldwide. This yeast can adapt to various external (trees, soil, and/or bird excreta) and internal environments (intracellular microenvironments of phagocytes and/or free-living in host tissues/fluids). The genetic basic for this adaptation is not fully characterized and primarily relies on a single reference C. neoformans strain. To uncover genes important for yeast infection and disease progression we have compared the gene expression from multiple strains of different lineages (VNI and VNBI) and sources (environment and clinic) under diverse conditions. Here, we used RNA sequencing to assess the transcriptional profiles of seven C. neoformans isolates grown in five representative in vitro, environmental, and in vivo conditions. We characterized gene expression differences between isolates from two of the major lineages of this species, VNI and VNBI, between these conditions. Comparing isolates from these two lineages, we find that genes showing lineage specific expression are enriched in sub-telomeric regions and in lineage specific gene clusters. The major gene expression differences common in all conditions are involved in the utilization of different sugar and nitrogen sources. Comparing gene expression in macrophages and cerebrospinal fluid (CSF) also revealed several specific pathways down-regulated in CSF including lipid and carbohydrate metabolism, and valine, leucine and isoleucine degradation, which may reflect the usage of host nutrients during growth in the mammalian subarachnoid space compared to MP. In summary, our study provides the widest view to date of the transcriptome variation of C. neoformans across natural strains and provides insights into genes important for major in vitro and in vivo growth stages.

ORGANISM(S): Cryptococcus neoformans

PROVIDER: GSE136879 | GEO | 2019/09/05

REPOSITORIES: GEO

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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.

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.

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.

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Landscape of gene expression variation of natural isolates of Cryptococcus neoformans in response to biologically relevant stresses

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