The Cryptococcus neoformans Rim101 Transcription Factor Directly Regulates Genes Required for Adaptation to the Host

Abstract

cThe Rim101 protein is a conserved pH-responsive transcription factor that mediates important interactions between several fungal pathogens and the infected host. In the human fungal pathogen Cryptococcus neoformans, the Rim101 protein retains conserved functions to allow the microorganism to respond to changes in pH and other host stresses. This coordinated cellular response enables this fungus to effectively evade the host immune response. Preliminary studies suggest that this conserved transcription factor is uniquely regulated in C. neoformans both by the canonical pH-sensing pathway and by the cyclic AMP (cAMP)/protein kinase A (PKA) pathway. Here we present comparative transcriptional data that demonstrate a strong concordance between the downstream effectors of PKA and Rim101. To define Rim101-dependent gene expression during a murine lung infection, we used nanoString profiling of lung tissue infected with a wild-type or rim101⌬ mutant strain. In this setting, we demonstrated that Rim101 controls the expression of multiple cell wall-biosynthetic genes, likely explaining the enhanced immunogenicity of the rim101⌬ mutant. Despite its divergent upstream regulation, the C. neoformans Rim101 protein recognizes a conserved DNA binding motif. Using these data, we identified direct targets of this transcription factor, including genes involved in cell wall regulation. Therefore, the Rim101 protein directly controls cell wall changes required for the adaptation of C. neoformans to its host environment. Moreover, we propose that integration of the cAMP/PKA and pH-sensing pathways allows C. neoformans to respond to a broad range of host-specific signals.

Model-driven mapping of transcriptional networks reveals the circuitry and dynamics of virulence regulation

“…S3; Supplemental File 5). Previously, binding specificity was known for only 2 TFs in Cryptococcus (Chun et al 2011;O'Meara et al 2014), both of which strongly support our independently derived PWMs.…”

Divergent Targets of Aspergillus fumigatus AcuK and AcuM Transcription Factors during Growth In Vitro versus Invasive Disease

“…For the C. albicans Bcr1 and Rim101 transcription factors, prior studies indicate that in vitro and in vivo profiles are fairly divergent (38,39). For Cryptococcus neoformans Rim101 and A. fumigatus SrbA, it appears that the in vivo and in vitro profiles of null mutants are fairly similar (32,40). We can now add A. fumigatus AcuM and AcuK to the group of transcription factors with divergent in vivo and in vitro mutant profiles.…”

Reciprocal functions of Cryptococcus neoformans copper homeostasis machinery during pulmonary infection and meningoencephalitis

“…(b) C57BL/6 mice were intranasally infected with H99 or ctr4D::NEO cells for 7 days. RNA was isolated as described previously 30 . Real-time PCR was performed to detect CTR1, CTR4, CMT1, CMT2 and ACT1.…”

“…However, recent work has demonstrated that Cuf1 activates both the Cu-detoxification machinery and the Cu-acquisition machinery, in response to high or low Cu conditions, respectively 12 . Moreover, although C. neoformans senses high Cu in the lung and Cu-detoxification genes are critical for fungal survival in the lung, CTR4 is still expressed in the lung at relatively low levels 5,18,30 .…”

“…One microgram of total RNA was used for cDNA synthesis, using the GoScript Reverse Transcription System (A5001, Promega), and real-time PCR was performed using a CFX Connect Thermocycler (Bio-rad) as previously described 5 . RNA was isolated from mice infected with C. neoformans as previously described 30 . Briefly, infected lung tissues were first cut into small pieces and resuspended in TRIzol reagent.…”