Effects of growth temperature upshift on cell cycle progression in Cryptococcus neoformans

Takeo, Kanji; Ohkusu, Misako; Kawamoto, Susumu

doi:10.1007/s10267-003-0138-8

Cited by 7 publications

(10 citation statements)

References 22 publications

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“…The presence of START in S. cerevisiae ensures budding and DNA replication are tightly coordinated (53). In contrast, our cell sorting studies in C. neoformans show that DNA replication without bud formation readily occurs both in vivo and in vitro, and are consistent with previous microscopy studies in both C. neoformans and C. deneoformans (18,(26)(27)(28)(29)54). These data suggest that START does not exist in Cryptococcus.…”

Section: Neoformanssupporting

confidence: 90%

“…During stationary phase and in vivo growth, we observed a pronounced G2 arrest. This unbudded G2 arrest was observed previously in various C. deneoformans and C. neoformans strains in response to other in vitro stresses in addition to nutrient deprivation (26,27), including high temperature (29) and hypoxia (28), and thus we refer to this alternative cell cycle as the Cryptococcus "stress cell cycle". Our in vitro stationary phase and titan cell formation experiments with the P CTR4 -CLN1 strain are important for several reasons.…”

Section: Neoformanssupporting

confidence: 57%

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The cyclin Cln1 controls polyploid titan cell formation following a stress-induced G2 arrest in Cryptococcus

Altamirano

et al. 2021

Preprint

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The pathogenic yeast Cryptococcus neoformans produces polyploid titan cells in response to the host lung environment that are critical for host adaptation and subsequent disease. We analyzed the in vivo and in vitro cell cycles to identify key aspects of the C. neoformans cell cycle that are important for the formation of titan cells. We identified unbudded 2C cells, referred to as a G2 arrest, produced both in vivo and in vitro in response to various stresses. Deletion of the non-essential cyclin Cln1 resulted in over-production of titan cells in vivo, and transient morphology defects upon release from stationary phase in vivo. Using a copper-repressible promoter PCTR4-CLN1 strain and a two-step in vitro titan cell formation assay, our in vitro studies revealed Cln1 functions after the G2 arrest. These studies highlight unique cell cycle alterations in C. neoformans that ultimately promote genomic diversity and virulence in this important fungal pathogen.

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Section: Neoformanssupporting

confidence: 90%

Section: Neoformanssupporting

confidence: 57%

The cyclin Cln1 controls polyploid titan cell formation following a stress-induced G2 arrest in Cryptococcus

Altamirano

et al. 2021

Preprint

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“…Previous studies of the C. neoformans cell cycle have identified a number of stressors that cause G2 arrest, including oxygen depletion [28], stationary growth phase [29], and temperature [30]. Under our experimental conditions, hyphal competency occurs prior to transfer to hyphal inducing conditions (starvation on filament agar) and not during growth on filament agar.…”

Section: Discussionmentioning

confidence: 90%

The Production of Monokaryotic Hyphae by Cryptococcus neoformans Can Be Induced by High Temperature Arrest of the Cell Cycle and Is Independent of Same-Sex Mating

Morris

Wickes

2013

PLoS Pathog

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Cryptococcus neoformans is a heterothallic fungal pathogen of humans and animals. Although the fungus grows primarily as a yeast, hyphae are produced during the sexual phase and during a process called monokaryotic fruiting, which is also believed to involve sexual reproduction, but between cells of the same mating type. Here we report a novel monokaryotic fruiting mechanism that is dependent on the cell cycle and occurs in haploid cells in the absence of sexual reproduction. Cells grown at 37°C were found to rapidly produce hyphae (∼4 hrs) and at high frequency (∼40% of the population) after inoculation onto hyphae-inducing agar. Microscopic examination of the 37°C seed culture revealed a mixture of normal-sized and enlarged cells. Micromanipulation of single cells demonstrated that only enlarged cells were able to produce hyphae and genetic analysis confirmed that hyphae did not arise from α-α mating or endoduplication. Cell cycle analysis revealed that cells grown at 37°C had an increased population of cells in G2 arrest, with the proportion correlated with the frequency of monokaryotic fruiting. Cell sorting experiments demonstrated that enlarged cells were only found in the G2-arrested population and only this population contained cells able to produce hyphae. Treatment of cells at low temperature with the G2 cell cycle arrest agent, nocodazole, induced hyphal growth, confirming the role of the cell cycle in this process. Taken together, these results reveal a mating-independent mechanism for monokaryotic fruiting, which is dependent on the cell cycle for induction of hyphal competency.

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“…In C. neoformans, conditions that delay polarized growth, such as temperature stress, result in the accumulation of G 2 stage cells that are larger than G 1 cells (Nichols et al, 2007; Takeo et al, 2003). Similarly, in a number of yeast species, stable diploids are larger than haploid cells (Hickman et al, 2013; Mortimer, 1958).…”

Section: Resultsmentioning

confidence: 99%

Two Rac paralogs regulate polarized growth in the human fungal pathogen Cryptococcus neoformans

Ballou

Selvig

Narloch

et al. 2013

Fungal Genetics and Biology

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A genome wide analysis of the human fungal pathogen Cryptococcus neoformans var. grubii has revealed a number of duplications of highly conserved genes involved in morphogenesis. Previously, we reported that duplicate Cdc42 paralogs provide C. neoformans with niche-specific responses to environmental stresses: Cdc42 is required for thermotolerance, while Cdc420 supports the formation of titan cells. The related Rho-GTPase Rac1 has been shown in C. neoformans var. neoformans to play a major role in filamentation and to share Cdc42/Cdc420 binding partners. Here we report the characterization of a second Rac paralog in C. neoformans, Rac2, and describe its overlapping function with the previously described CnRac, Rac1. Further, we demonstrate that the Rac paralogs play a primary role in polarized growth via the organization of reactive oxygen species and play only a minor role in the organization of actin. Finally, we provide preliminary evidence that pharmacological inhibitors of Rac activity and actin stability have synergistic activity.

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Effects of growth temperature upshift on cell cycle progression in Cryptococcus neoformans

Cited by 7 publications

References 22 publications

The cyclin Cln1 controls polyploid titan cell formation following a stress-induced G2 arrest in Cryptococcus

The cyclin Cln1 controls polyploid titan cell formation following a stress-induced G2 arrest in Cryptococcus

The Production of Monokaryotic Hyphae by Cryptococcus neoformans Can Be Induced by High Temperature Arrest of the Cell Cycle and Is Independent of Same-Sex Mating

Two Rac paralogs regulate polarized growth in the human fungal pathogen Cryptococcus neoformans

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