Project description:CircRNAs are a recently well-known regulator that mediates a variety of biological processes. Cryptococcus neoformans is an environmental fungal pathogen that can cause fatal cryptococcal meningitis in immunocompromised individuals. However, the involvement of circRNA in cryptococcal infection remains unclear. In this study, high‐throughput microarray was performed to identify the circRNA expression profile in cryptococcal meningitis patients.
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:to identify transcriptomic biomarker pathways in peripheral blood that are associated with or predict the development of death or fatal C-IRIS among patients with CM who were enrolled in the Cryptococcal Optimal ART Timing (COAT) Trial.
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:To contextualize the cryptococcal Spt-Ada-Gcn5 Acetyltransferase (SAGA) member Ada2 in the capsule regulatory network, RNA-Seq was performed on wildtype, ada2Δ and two other transcription factors, nrg1Δ and cir1Δ, which like ada2Δ are also defective for capsule formation, virulence and filamentation.
Project description:Cryptococcal disease pathogenesis is associated with the induction of type 2 immune response which is largely mediated by adaptive T helper cells. Recently, epithelial cell-derived IL-33 and IL-25 are recognized as key mediators in driving pathogenic type 2 inflammation during C. neoformans infection. Although IL-25 and IL-33 exhibit a combinatorial and closely related function, the differential effect of these cytokines in the regulation of host immune response against C. neoformans infection is still elusive. We observed a predominantly increase of IL-25/IL-33 responsive Th cells within the lung after infection, especially at the chronic infection phase. The ex vivo stimulation of cryptococcal-specific Th cells demonstrated combinatorial effect of IL-25 and IL-33 in promoting the production of type 2 cytokines. A comparative transcriptomic analysis revealed coordinatel effects of these cytokines in promoting activation, survival, and homeostasis of adaptive Th cells during C. neoformans infection. The expression of type 2 cytokines and chemokine was absent in Th cells of Il17rb-/- mice, indicating the requirement of IL-25-mediated Th2-type immune responses during C. neoformans infection. Further analysis of the degree of virulence indicated a positive correlation between the frequency of IL-17RB/ST2-expressing Th cells and cryptococcal brain dissemination in vivo.
Project description:Cryptococcus neoformans is an important pathogen that annually kills 200,000 people worldwide. It survives in the environment as a yeast or spore and can also proliferate within host macrophages after being inhaled into the lungs. In conditions of immunocompromise, cryptococcal cells can escape from the lungs to the brain, where they cause a deadly meningoencephalitis that is both difficult and expensive to treat. Cryptococcal adaptation to the harsh lung environment is a critical first step in its pathogenesis, and consequently a compelling topic of study. This adaptation is mediated by a complex transcriptional program that integrates cellular responses to environmental stimuli. Although several key regulators in this process have been examined, one important protein complex that modulates transcription yet remains understudied in C. neoformans is the Mediator complex. In other organisms, this complex promotes transcription of specific genes by increasing the assembly of the RNA Polymerase II pre-initiation complex. We have focused on the Kinase Module of the Mediator complex, which consists of cyclin C (Ssn801), cyclin-dependent kinase 8 (Cdk8), and two other proteins (Med12 and Med13). This module provides important inhibitory control of Mediator complex assembly and activity. Using a transcriptomics approach, we discovered that Cdk8 and Ssn801 together regulate cryptococcal functions relevant to pathogenesis, including the response to oxidative stress. Deletion of CDK8 resulted in altered mitochondrial morphology and the dysregulation of genes involved in oxidation-reduction processes, such that this strain exhibited increased susceptibility to oxidative stress. This resulted in an inability of mutant cells to proliferate within phagocytes, decreased lung burdens, and attenuated virulence in in vivo studies. These findings increase our understanding of cryptococcal adaptation to the host environment and its regulation of oxidative stress resistance and virulence.
Project description:To contextualize the cryptococcal Spt-Ada-Gcn5 Acetyltransferase (SAGA) member Ada2 in the capsule regulatory network, RNA-Seq was performed on wildtype, ada2M-NM-^T and two other transcription factors, nrg1M-NM-^T and cir1M-NM-^T, which like ada2M-NM-^T are also defective for capsule formation, virulence and filamentation. Mutant and wildtype cells were grown in capsule inducing and non-inducing conditions for 90 minutes and transcriptional profiling was performed by RNA-Seq analysis.