Functional dissection of the regulatory mechanism of the atypical AP-1-like transcription factor, Yap1, in Cryptococcus neoformans

AP-1 like transcription factors play evolutionarily conserved roles in oxidative stress responses as redox sensors in eukaryotes. In this study, we aim to elucidate the regulatory mechanism of an atypical yeast AP-1 like protein, Yap1, in the stress response and virulence of Cryptococcus neoformans. YAP1 expression was induced not only by oxidative stresses, such as H2O2 and diamide, but also by other environmental stresses, such as osmotic and membrane destabilizing stresses. Supporting these data, Yap1 was involved in osmotic and membrane stress responses as well as oxidative stress responses. Pleiotropic roles of Yap1 in diverse biological processes were supported by transcriptome analysis data showing that more than 162 genes are differentially regulated by Yap1. This analysis also provided a clue that Yap1 is involved in carbohydrate metabolism and indeed we found that Yap1 promotes cellular resistance to toxic cellular metabolites produced during glycolysis, such as methylglyoxal. Finally, we demonstrated that Yap1 played a minor role in survival of C. neoformans within hosts. WT (H99) and yap1∆ mutant (YSB815) strains were incubated in liquid YPD medium overnight at 30°C. The cells were subcultured in fresh YPD medium and then further incubated at 30°C until OD600 reached 0.8 . The WT and yap1∆ mutant cells were harvested and lyophilized. Three biologically independent cultures were prepared for each strain. Total RNAs were isolated by Easy-BLUE (iNtRON) and purified with an RNeasy Mini Kit (Qiagen). cDNA libraries were constructed with the TruSeq RNA library kit v2 (Illumina) using 1 g of total RNA and sequenced by Illumina platform.