Project description:This SuperSeries is composed of the following subset Series: GSE31911: Cryptococcal H99 cells grown in 8 conditions for capsule induction GSE32049: RNA-Seq analysis of ada2?, nrg1? and cir1? and KN99? wildtype cells in capsule inducing and non-inducing conditions GSE32075: ChIP-Seq of H3K9 acetylation for wildtype and ada2? cells in Cryptococcus neoformans Refer to individual Series
Project description:Wild type strain H99 compared to independent sir2 deletion mutants grown to mid-log (0.6 OD600) in rich medium (YPD) shaking at 250rpm in baffled flasks.
Project description:We report on our study the role of C. neoformans transcription factor Pdr802, whose expression is highly induced under host-like conditions in vitro and is critical for C. neoformans dissemination and virulence in a mouse model of infection. We found that direct targets of Pdr802 include the calcineurin targets Had1 and Pmc1, which are important for C. neoformans virulence, the transcription factor Bzp4, which promotes cryptococcal melanization and capsule thickness, and 35 transmembrane transporters. Notably, a strain engineered to lack Pdr802 showed a dramatically increased population of Titan cells. Since Titan cells are not phagocyted and do not disseminate via the Trojan horse mechanism or via penetration of biological barriers, this likely explains the reduced dissemination of pdr802 cells to the central nervous system and consequently reduced pathogenicity of this strain. The role of Pdr802 as a negative regulator of titanisation is thus critical for cryptococcal virulence.
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.
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.
Project description:We report on our study the role of C. neoformans transcription factor Pdr802, whose expression is highly induced under host-like conditions in vitro and is critical for C. neoformans dissemination and virulence in a mouse model of infection. We found that direct targets of Pdr802 include the calcineurin targets Had1 and Pmc1, which are important for C. neoformans virulence, the transcription factor Bzp4, which promotes cryptococcal melanization and capsule thickness, and 35 transmembrane transporters. Notably, a strain engineered to lack Pdr802 showed a dramatically increased population of Titan cells. Since Titan cells are not phagocyted and do not disseminate via the Trojan horse mechanism or via penetration of biological barriers, this likely explains the reduced dissemination of pdr802 cells to the central nervous system and consequently reduced pathogenicity of this strain. The role of Pdr802 as a negative regulator of titanisation is thus critical for cryptococcal virulence.
Project description:Purpose: Investigate the dynamics of cryptococcal cell and transcriptional remodeling during pulmonary infection in a murine model Methods: Dual-RNA sequencing Sample preparation - C57BL/6 mice were infected intratracheally with the H99 strain to analyze the transcriptome. After 6h or 240h of infection, BALF obtained from 6 mice of each condition were pooled together, generating two replicates of 6h and 240h (10d). BALF was centrifuged at 1200 x g and resuspended in 1mL TRIzol Reagent (Invitrogen Life Technologies) for RNA isolation, according to the manufactures' protocol. RNA from H99 yeasts grown in YPD was used as control. Results: Dual RNA-Seq analysis of C. neoformans and mice revealed molecular signatures of early and late events of infection We analyzed the up and downregulated genes after 6h and 10 days of infection, compared to the inoculated yeast (YPD x 6h and YPD x 10d) and the differentially expressed genes (DEGs) between 6h and 10 days of infection (designated BAL6h x BAL10d). These analyses revealed molecular signatures unique to early and late stages of infection. Conclusions: Our findings support a scenario in which the fungus initially deploys mechanisms aimed at survival, proliferation and tissue invasion. Later, the fungus may focus on mechanisms aimed at resistance to the immune response and colonization, that are crucial for disease development. Overall, our study provides new insights into understanding the biology of C. neoformans during infection and generating perspectives for the survey for new therapeutic and diagnostic targets for cryptococcosis.
Project description:The Cryptococcus neoformans NRG1 gene was identified using gene microarrays to define putative transcription factor genes regulated by the cyclic AMP (cAMP) signal transduction pathway. Disruption of NRG1 results in delayed capsule formation and mating, two phenotypes that are directly controlled by cAMP signaling. Putative targets of the Nrg1 transcription factor were identified using a second genome microarray to define differences in the transcriptomes of the wild-type and nrg1 mutant strains. These experiments implicate Nrg1 in the transcriptional control of multiple genes involved in carbohydrate metabolism and substrate oxidation, as well as the UGD1 gene encoding a UDP-glucose dehydrogenase required for polysaccharide capsule production and cell wall integrity. In addition to being under transcriptional control of the cAMP pathway, Nrg1 contains a putative protein kinase A phosphorylation site; mutation of this motif results in reduced Nrg1 activity. Consistent with prior studies in hypocapsular mutants, the nrg1 mutant strain is attenuated in an animal model of disseminated cryptococcal disease.
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.