Novel biological functions of the NsdC transcription factor in Aspergillus fumigatus

The fungal zinc
finger transcription factor NsdC is named after, and is best known for, its
essential role in sexual reproduction (never in sexual development).
In previous studies with Aspergillus nidulans it was also shown to have
roles in promotion of vegetative growth and suppression of asexual conidiation.
In this study the function of the nsdC homologue in the opportunistic
human pathogen A. fumigatus was investigated. NsdC was again found to be
essential for sexual development, with deletion of the nsdC gene in both
MAT1-1 and MAT1-2 mating partners of a cross leading to complete
loss of fertility. However, a functional copy of nsdC in one mating
partner was sufficient to allow sexual reproduction. Deletion of nsdC also
led to decreased vegetative growth and allowed conidiation in liquid cultures,
again consistent with previous findings. However, NsdC in A. fumigatus was
shown to have additional biological functions including response to calcium
stress, correct organization of cell wall structure and response to the cell
wall stressors. Furthermore, virulence and host
immune recognition was affected. Gene expression studies involving chromatin immunoprecipitation
(ChIP) of RNA polymerase II (PolII) coupled to sequencing (Seq) revealed that deletion of nsdC resulted in
changes in expression of over 620 genes under basal growth conditions. This demonstrated
that this transcription factor
mediates the activity of a wide variety of signalling and metabolic pathways
and indicates that despite the
naming of the gene, the promotion of sexual reproduction is just one among multiple
roles of NsdC.