ABSTRACT
Cryptococcus neoformans causes fatal fungal meningoencephalitis. Here, we study the roles played by fungal kinases and transcription factors (TFs) in blood-brain barrier (BBB) crossing and brain infection in mice. We use a brain infectivity assay to screen signature-tagged mutagenesis (STM)-based libraries of mutants defective in kinases and TFs, generated in the C. neoformans H99 strain. We also monitor in vivo transcription profiles of kinases and TFs during host infection using NanoString technology. These analyses identify signalling components involved in BBB adhesion and crossing, or survival in the brain parenchyma. The TFs Pdr802, Hob1, and Sre1 are required for infection under all the conditions tested here. Hob1 controls the expression of several factors involved in brain infection, including inositol transporters, a metalloprotease, PDR802, and SRE1. However, Hob1 is dispensable for most cellular functions in Cryptococcus deuterogattii R265, a strain that does not target the brain during infection. Our results indicate that Hob1 is a master regulator of brain infectivity in C. neoformans.
Subject(s)
Blood-Brain Barrier/metabolism , Cryptococcus neoformans/pathogenicity , Homeodomain Proteins/metabolism , Meningitis, Cryptococcal/pathology , Meningoencephalitis/pathology , Transcription Factors/metabolism , Animals , Brain/microbiology , Brain/pathology , Cryptococcus gattii/genetics , Cryptococcus gattii/metabolism , Cryptococcus gattii/pathogenicity , Cryptococcus neoformans/genetics , Cryptococcus neoformans/metabolism , Disease Models, Animal , Female , Fungal Proteins , Gene Expression Profiling , Gene Expression Regulation, Fungal , Homeodomain Proteins/genetics , Humans , Meningitis, Cryptococcal/microbiology , Meningoencephalitis/microbiology , Mice , Mutagenesis , Mutation , Permeability , Phosphotransferases/genetics , Signal Transduction/genetics , Transcription Factors/geneticsABSTRACT
Cryptococcus neoformans causes life-threatening meningoencephalitis in humans, but its overall biological and pathogenic regulatory circuits remain elusive, particularly due to the presence of an evolutionarily divergent set of transcription factors (TFs). Here, we report the construction of a high-quality library of 322 signature-tagged gene-deletion strains for 155 putative TF genes previously predicted using the DNA-binding domain TF database, and examine their in vitro and in vivo phenotypic traits under 32 distinct growth conditions. At least one phenotypic trait is exhibited by 145 out of 155 TF mutants (93%) and â¼85% of them (132/155) are functionally characterized for the first time in this study. The genotypic and phenotypic data for each TF are available in the C. neoformans TF phenome database (http://tf.cryptococcus.org). In conclusion, our phenome-based functional analysis of the C. neoformans TF mutant library provides key insights into transcriptional networks of basidiomycetous fungi and human fungal pathogens.