An Opaque Cell-Specific Expression Program of Secreted Proteases and Transporters Allows Cell-Type Cooperation in<i>Candida albicans</i>

Lohse, Matthew B.; Brenes, Lucas R; Ziv, Naomi; Winter, Michael E.; Craik, Charles S.; Johnson, Alexander D.

doi:10.1534/genetics.120.303613

Cited by 8 publications

(7 citation statements)

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“…Many virulence factors provide important functions required for the pathogenesis of C. albicans , such as morphogenesis (the transition between yeast and hyphae), white (W)/opaque (O) switching [24], secreted aspartic proteases (Saps) and adhesins [25]. Ten secreted aspartic proteases (Saps) have been identified in C. albicans , which are encoded by the SAP genes ( SAP1 to SAP10 ) [26] and associated with bovine serum albumin (BSA) utilisation [27]. It has been demonstrated that Saps are involved in protection from host defence proteins, biofilm formation and adhesion, among other functions [27].…”

Section: Introductionmentioning

confidence: 99%

Transcriptional regulation of autophagy, cell wall stress response and pathogenicity by Pho23 in C. albicans

et al. 2022

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The modification of chromatin by histone deacetylases (HDACs) has critical roles in transcriptional regulation. In this study, we identified the Rpd3 HDAC complex component Pho23 in Candida albicans and explored its role in the transcriptional regulation of physiological processes. PHO23 deletion increased autophagic activity and upregulated the transcription of ATG genes. Moreover, the deletion of PHO23 severely impaired cell wall stress resistance and reduced the cell wall integrity (CWI) pathway in response to cell wall stress. Furthermore, the pho23Δ/Δ mutant had partial defects in hyphal development and protease secretion, which were associated with the downregulation of genes involved in hyphal development (e.g. HWP1, ALS3 and ECE1) and genes encoding secreted aspartic proteases (e.g. SAP4, SAP5, SAP6 and SAP9). In addition, the deletion of PHO23 strongly attenuated systemic infection and kidney fungal burden in mice, demonstrating that Pho23 is required for the virulence of C. albicans. Together, our results revealed that Pho23 regulates many key physiological processes in C. albicans at the transcriptional level. These data also shed light on the potential for exploiting Rpd3 HDAC complex‐related proteins as antifungal targets.

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Section: Introductionmentioning

confidence: 99%

Transcriptional regulation of autophagy, cell wall stress response and pathogenicity by Pho23 in C. albicans

et al. 2022

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“…It is known that opaque cells are the mating competent cell type [ 21 ] and are less susceptible to phagocytosis by macrophages, potentially promoting immune evasion [ 24 , 46 ]. Our recent work has also shown that, due to a specialized secreted protease program, a small number of opaque cells can promote growth of a large white cell population; thus, the 2 cell types can act synergistically [ 47 ]. Aside from its physiological roles, white-opaque switching has many advantages as a eukaryotic system to study stochastic phenotypic switching.…”

Section: Discussionmentioning

confidence: 99%

Multiple molecular events underlie stochastic switching between 2 heritable cell states in fungi

2022

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Eukaryotic transcriptional networks are often large and contain several levels of feedback regulation. Many of these networks have the ability to generate and maintain several distinct transcriptional states across multiple cell divisions and to switch between them. In certain instances, switching between cell states is stochastic, occurring in a small subset of cells of an isogenic population in a seemingly homogenous environment. Given the scarcity and unpredictability of switching in these cases, investigating the determining molecular events is challenging. White-opaque switching in the fungal species Candida albicans is an example of stably inherited cell states that are determined by a complex transcriptional network and can serve as an experimentally accessible model system to study characteristics important for stochastic cell fate switching in eukaryotes. In standard lab media, genetically identical cells maintain their cellular identity (either “white” or “opaque”) through thousands of cell divisions, and switching between the states is rare and stochastic. By isolating populations of white or opaque cells, previous studies have elucidated the many differences between the 2 stable cell states and identified a set of transcriptional regulators needed for cell type switching and maintenance of the 2 cell types. Yet, little is known about the molecular events that determine the rare, stochastic switching events that occur in single cells. We use microfluidics combined with fluorescent reporters to directly observe rare switching events between the white and opaque states. We investigate the stochastic nature of switching by beginning with white cells and monitoring the activation of Wor1, a master regulator and marker for the opaque state, in single cells and throughout cell pedigrees. Our results indicate that switching requires 2 stochastic steps; first an event occurs that predisposes a lineage of cells to switch. In the second step, some, but not all, of those predisposed cells rapidly express high levels of Wor1 and commit to the opaque state. To further understand the rapid rise in Wor1, we used a synthetic inducible system in Saccharomyces cerevisiae into which a controllable C. albicans Wor1 and a reporter for its transcriptional control region have been introduced. We document that Wor1 positive autoregulation is highly cooperative (Hill coefficient > 3), leading to rapid activation and producing an “all or none” rather than a graded response. Taken together, our results suggest that reaching a threshold level of a master regulator is sufficient to drive cell type switching in single cells and that an earlier molecular event increases the probability of reaching that threshold in certain small lineages of cells. Quantitative molecular analysis of the white-opaque circuit can serve as a model for the general understanding of complex circuits.

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“…Recent work has also shown that, due to a specialized secreted protease program, a small number of opaque cells can promote growth of a large white cell population; thus the two cell types can act synergistically (Lohse et al, 2020). Aside from its physiological roles, white-opaque switching has many advantages as a eukaryotic system to study stochastic phenotypic switching.…”

Section: Discussionmentioning

confidence: 99%

“…It is known that opaque cells are the mating competent cell type (Miller & Johnson, 2002) and are less susceptible to phagocytosis by macrophages, potentially promoting immune evasion (Lohse & Johnson, 2008;Sasse et al, 2013). Recent work has also shown that, due to a specialized secreted protease program, a small number of opaque cells can promote growth of a large white cell population; thus the two cell types can act synergistically (Lohse et al, 2020). Aside from its physiological roles, white-opaque switching has many advantages as a eukaryotic system to study stochastic phenotypic switching.…”

Section: Discussionmentioning

confidence: 99%

Multiple molecular events underlie stochastic switching between two heritable cell states in a eukaryotic system

Ziv

Brenes

Johnson

2021

Preprint

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Eukaryotic transcriptional networks are often large and contain several levels of feedback regulation. Many of these networks exhibit bistability, the ability to generate and stably maintain two distinct transcriptional states and to switch between them. In certain instances, switching between cell states is stochastic, occurring in a small subset of cells of an isogenic population in a seemingly homogenous environment. Given the scarcity and unpredictability of switching in these cases, investigating the determining molecular events is challenging. White-opaque switching in the fungal species Candida albicans is a complex bistable eukaryotic system and can serve as an experimentally accessible model system to study characteristics important for bistability and stochastic cell fate switching. In standard lab media, switching is rare, and genetically identical cells maintain their cellular identity (either “white” or “opaque”) through thousands of cell divisions. By isolating populations of white or opaque cells and measuring switching frequencies, previous studies have elucidated the many differences between the two cell states and identified a set of transcriptional regulators needed for cell type switching. Yet little is known about the molecular events that determine the rare, stochastic switching events that occur in single cells. We use microfluidics combined with fluorescent reporters to directly observe rare switching events between the white and opaque states. We investigate the stochastic nature of switching by beginning with white cells and monitoring the activation of Wor1, a master regulator and marker for the opaque state, in single cells and throughout cell pedigrees. Our results indicate that switching requires two stochastic steps; first an event occurs that predisposes a lineage of cells to switch. In the second step, some but not all, of those predisposed cells rapidly express high levels of Wor1 and commit to the opaque state. To further understand the rapid rise in Wor1, we used a synthetic inducible system in Saccharomyces cerevisiae into which a controllable C. albicans Wor1 and a reporter for its transcriptional control region have been introduced. We document that Wor1 positive autoregulation is highly cooperative (Hill coefficient > 3), leading to rapid activation and producing an “all or none” rather than a graded response. Taken together, our results suggest that reaching a threshold level of a master regulator is sufficient to drive cell type switching in single cells and that an earlier molecular event increases the probability of reaching that threshold in certain small lineages of cells. Quantitative molecular analysis of bistability in the white-opaque circuit can serve as a model for the general understanding of complex circuits.

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An Opaque Cell-Specific Expression Program of Secreted Proteases and Transporters Allows Cell-Type Cooperation inCandida albicans

Cited by 8 publications

References 99 publications

Transcriptional regulation of autophagy, cell wall stress response and pathogenicity by Pho23 in C. albicans

Transcriptional regulation of autophagy, cell wall stress response and pathogenicity by Pho23 in C. albicans

Multiple molecular events underlie stochastic switching between 2 heritable cell states in fungi

Multiple molecular events underlie stochastic switching between two heritable cell states in a eukaryotic system

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