Cryptococcal dissemination to the central nervous system requires the vacuolar calcium transporter Pmc1

Abstract

Cryptococcus neoformans is a basidiomycetous yeast and the cause of cryptococcosis in immunocompromised individuals. The most severe form of the disease is meningoencephalitis, which is one of the leading causes of death in HIV/AIDS patients. In order to access the central nervous system, C. neoformans relies on the activity of certain virulence factors such as urease, which allows transmigration through the blood-brain barrier. In this study, we demonstrate that the calcium transporter Pmc1 enables C. neoformans to penetrate the central nervous system, because the pmc1 null mutant failed to infect and to survive within the brain parenchyma in a murine systemic infection model. To investigate potential alterations in transmigration pathways in these mutants, global expression profiling of the pmc1 mutant strain was undertaken, and genes associated with urease, the Ca -calcineurin pathway, and capsule assembly were identified as being differentially expressed. Also, a decrease in urease activity was observed in the calcium transporter null mutants. Finally, we demonstrate that the transcription factor Crz1 regulates urease activity and that the Ca -calcineurin signalling pathway positively controls the transcription of calcium transporter genes and factors related to transmigration.

Calcium Binding Protein Ncs1 Is Calcineurin Regulated in Cryptococcus neoformans and Essential for Cell Division and Virulence

“…As proven in other studies, the disruption of Ca 2+ homeostasis components is important for cryptococcal pathogenicity ( 29 – 33 , 51 ). To determine whether disruption of Ncs1-mediated calcium homeostasis also contributes to pathogenicity, we compared the virulence of the ncs1Δ mutant strain to that observed for the WT and ncs1Δ :: NCS1 strains in a mouse inhalation model of cryptococcosis.…”

“…Ncs1 activity is essential for C. neoformans virulence. As proven in other studies, the disruption of Ca 2ϩ homeostasis components is important for cryptococcal pathogenicity (29)(30)(31)(32)(33)51). To determine whether disruption of Ncs1-mediated calcium homeostasis also contributes to pathogenicity, we compared the virulence of the ncs1⌬ mutant strain to that observed for the WT and ncs1⌬::NCS1 strains in a mouse inhalation The transcript levels of genes encoding the calcium transporters, CCH1 and MID1, were evaluated using RT-qPCR.…”

“…In C. neoformans , these proteins include Cch1, a Ca 2+ voltage-gated channel essential for virulence, and Mid1, a stretch-activated Ca 2+ -channel, both found in the plasma membrane ( 19 , 29 ). Other cryptococcal calcium transporters that also promote virulence include the Ca 2+ ATPase EcaI, found in sarcoplasmic/endoplasmic reticulum, and the H + /Ca 2+ exchanger protein Vcx1 and the Ca 2+ ATPase Pmc1, both localized on vacuolar membranes and responsible for Ca 2+ storage ( 30 – 33 ). Pmc1 is also required for C. neoformans transmigration through the blood-brain barrier (BBB), proving that Pmc1-regulated Ca 2+ homeostasis is crucial for disease progression ( 33 ).…”

Dissecting the Roles of the Calcineurin Pathway in Unisexual Reproduction, Stress Responses, and Virulence in Cryptococcus deneoformans

“…Moreover, calcineurin regulates calcium homeostasis through the transcription factor Crz1 in yeast (Matheos et al 1997;Stathopoulos and Cyert 1997). In C. neoformans, calcineurin and Crz1 positively regulate expression of the VCX1 gene and the PMC1 gene encoding the vacuolar calcium transporter Pmc1 to confer higher tolerance to calcium (Kmetzsch et al 2010(Kmetzsch et al , 2013Chow et al 2017;Squizani et al 2017). Several studies have shown that the calcineurin/Crz1 regulatory network has been extensively rewired in different fungal species (Yoshimoto et al 2002;Kim et al 2010;Soriani et al 2010;Chatfield-Reed et al 2016;Chow et al 2017), which may account for the high calcium sensitivity observed in cna1D and cnb1D mutants in Cryptococcus.…”

The Vacuolar Ca 2+ ATPase Pump Pmc1p Is Required for Candida albicans Pathogenesis

“…In fungi, two systems are responsible for sequestering cytoplasmic Ca 2+ ions into the vacuole, namely, the H + /Ca 2+ exchanger Vcx1p (9–11), which uses the proton gradient across the vacuolar membrane (generated by the V-ATPase) to drive Ca 2+ transport, and the P-type ATPase Pmc1p (11, 12). Both Pmc1p and Vcx1p are required for Cryptococcus neoformans to colonize lung or brain tissue in a mouse model of infection (13–15). While Aspergillus fumigatus, a major cause of pulmonary as well as disseminated infections of humans, has three Pmc1p homologues ( PMCA , PMCB , and PMCC ), with PMCC seemingly essential for viability and PMCA required for virulence in a neutropenic mouse model of invasive pulmonary aspergillosis (16).…”