Distinct and Redundant Roles of Protein Tyrosine Phosphatases Ptp1 and Ptp2 in Governing the Differentiation and Pathogenicity of Cryptococcus neoformans

Abstract

bProtein tyrosine phosphatases (PTPs) serve as key negative-feedback regulators of mitogen-activated protein kinase (MAPK) signaling cascades. However, their roles and regulatory mechanisms in human fungal pathogens remain elusive. In this study, we characterized the functions of two PTPs, Ptp1 and Ptp2, in Cryptococcus neoformans, which causes fatal meningoencephalitis. PTP1 and PTP2 were found to be stress-inducible genes, which were controlled by the MAPK Hog1 and the transcription factor Atf1. Ptp2 suppressed the hyperphosphorylation of Hog1 and was involved in mediating vegetative growth, sexual differentiation, stress responses, antifungal drug resistance, and virulence factor regulation through the negative-feedback loop of the HOG pathway. In contrast, Ptp1 was not essential for Hog1 regulation, despite its Hog1-dependent induction. However, in the absence of Ptp2, Ptp1 served as a complementary PTP to control some stress responses. In differentiation, Ptp1 acted as a negative regulator, but in a Hog1-and Cpk1-independent manner. Additionally, Ptp1 and Ptp2 localized to the cytosol but were enriched in the nucleus during the stress response, affecting the transient nuclear localization of Hog1. Finally, Ptp1 and Ptp2 played minor and major roles, respectively, in the virulence of C. neoformans. Taken together, our data suggested that PTPs could be exploited as novel antifungal targets.

High osmolarity glycerol response PtcB phosphatase is important for Aspergillus fumigatus virulence

“…Interestingly, these phosphatases positively regulate the phosphorylation state of BcSak1 and BcBmp3 (the homologue of Mpk1) in B. cinerea under stress conditions (Yang et al ., 2013a,b). In the human pathogen C. neoformans PTP Ptp2 (the S. cerevisiae Ptp2 homologs) suppressed the hyperphosphorylation of Hog1 and was involved in mediating vegetative growth, sexual differentiation, stress responses, antifungal drug resistance and virulence factor regulation through a negative‐feedback loop influencing the HOG pathway (Lee et al ., ). In C. neoformans , Ptp1 acted as a negative regulator of differentiation, but in a Hog1‐ and pheromone sensing Cpk1 MAPKs‐independent manner (Lee et al ., ).…”

“…The calcineurin phosphatase is central to calcium signaling and plays an important role in determining fungal cell morphology and virulence (Steinbach et al, 2007). In human (Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus) and plant pathogens (Fusarium spp., Sclerotinia sclerotiorum, Ustilago maydis, Magnaporthe oryzae and Botrytis cinerea), other protein phosphatases have been described as regulating mating, asexual development, differentiation, cation homeostasis, CWI, oxidative stress, virulence and pathogenicity (Erental et al, 2007;Di Stasio et al, 2009;Feng et al, 2010;Jiang et al, 2011;Adám et al, 2012;Du et al, 2013;Shin et al, 2013;Yang et al, 2013a,b;Lee et al, 2014;Muszkieta et al, 2014;Yu et al, 2014).…”

Intron retention-dependent gene regulation in Cryptococcus neoformans

“…grubii H99S strain by using the modified split marker/double joint PCR with primers listed in Table S10 as previously reported54. The two split gene disruption cassettes were introduced into the H99S strain by biolistic transformation as previously described55.…”

Fungicide resistance toward fludioxonil conferred by overexpression of the phosphatase gene MoPTP2 in Magnaporthe oryzae

“…Phosphatases may be key players in osmoregulation, because phosphorylation and dephosphorylation are assumed to be essential to regulate the nuclear translocation of the MAPK Hog1p in yeast (Reiser et al ., ). Further studies in yeasts have shown that the phosphatases Ptc1p and Ptp2p regulate Hog1p negatively by dephosphorylation (Wurgler‐Murphy et al ., ; Warmka et al ., ; Young et al ., ; Mapes et al ., ; Lee et al ., ). Phosphorylation‐dependent nuclear import/export mechanisms have been well documented in yeast and were called the ‘binary switch’ (Hood and Silver, ).…”