<i>Candida albicans</i>
            -Conditioned Medium Protects Yeast Cells from Oxidative Stress: a Possible Link between Quorum Sensing and Oxidative Stress Resistance

Westwater, Caroline; Balish, Edward; Schofield, David A.

doi:10.1128/ec.4.10.1654-1661.2005

Cited by 115 publications

(103 citation statements)

References 68 publications

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“…These genes function in diverse stress responses. These mutants are interesting because farnesol treatment leads to increased survival after heat shock (17) and confers protection from oxidative stress (5,6,32). Osmotic stress protection is also mediated by the cAMP/PKA pathway (4,5).…”

Section: Resultsmentioning

confidence: 99%

“…It blocks the transition from yeast to filaments once it accumulates above a threshold level (3). It also has an inhibitory role in biofilm formation (4) and a protective role against oxidative stress (5,6). In addition, very high levels of farnesol can increase chlamydospore formation (7), while even very low levels of farnesol induce cell death by necrosis in opaque cells (8).…”

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confidence: 99%

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Candida albicans Czf1 and Efg1 Coordinate the Response to Farnesol during Quorum Sensing, White-Opaque Thermal Dimorphism, and Cell Death

et al. 2013

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bQuorum sensing by farnesol in Candida albicans inhibits filamentation and may be directly related to its ability to cause both mucosal and systemic diseases. The Ras1-cyclic AMP signaling pathway is a target for farnesol inhibition. However, a clear understanding of the downstream effectors of the morphological farnesol response has yet to be unraveled. To address this issue, we screened a library for mutants that fail to respond to farnesol. Six mutants were identified, and the czf1⌬/czf1⌬ mutant was selected for further characterization. Czf1 is a transcription factor that regulates filamentation in embedded agar and also whiteto-opaque switching. We found that Czf1 is required for filament inhibition by farnesol under at least three distinct environmental conditions: on agar surfaces, in liquid medium, and when embedded in a semisolid agar matrix. Since Efg1 is a transcription factor of the Ras1-cyclic AMP signaling pathway that interacts with and regulates Czf1, an efg1⌬/efg1⌬ czf1⌬/czf1⌬ mutant was tested for filament inhibition by farnesol. It exhibited an opaque-cell-like temperature-dependent morphology, and it was killed by low farnesol levels that are sublethal to wild-type cells and both efg1⌬/efg1⌬ and czf1⌬/czf1⌬ single mutants. These results highlight a new role for Czf1 as a downstream effector of the morphological response to farnesol, and along with Efg1, Czf1 is involved in the control of farnesol-mediated cell death in C. albicans.

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Candida albicans Czf1 and Efg1 Coordinate the Response to Farnesol during Quorum Sensing, White-Opaque Thermal Dimorphism, and Cell Death

et al. 2013

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“…The lag phase after C. albicans cells are transferred to either hypha-inducing and noninducing media is decreased when tyrosol is present in the medium (8). Tyrosol does not appear to have a role in detoxifying oxidants in the medium (98). Microarray studies showed that tyrosol prevents the temporary decrease in expression of genes involved in DNA replication, chromosome seg-regation, and cell cycle regulation that normally occurs during that lag phase that follows culture dilution (8).…”

Section: Other Fungal Autoregulatory Moleculesmentioning

confidence: 99%

“…In addition to its effects on hyphal development, farnesol (35 M) confers some protection to hydrogen peroxide, and this effect does not appear to be due to the increased transcription of genes involved in the oxidative stress response, including superoxide dismutase (SOD1 and SOD2) and catalase (CAT1) (98). The presence of farnesol does lead to the increased transcription of the genes encoding the CDR1 and CDR2 efflux pumps (15).…”

Section: Albicans and Autoregulationmentioning

confidence: 99%

Talking to Themselves: Autoregulation and Quorum Sensing in Fungi

2006

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Extracellular autoinducing compounds in the supernatants of microbial cultures were first recognized for their roles in the induction of genetic competence in gram-positive bacteria (17,94) and in the regulation of light production in marine vibrios (60). In 1994, this form of population-level regulation in microbes was dubbed "quorum sensing" since it enabled bacterial cells to chemically measure the density of the surrounding population (18). Subsequently, many examples of cell densitydependent regulation by extracellular factors have been found in diverse microorganisms. The widespread incidence of diverse quorum-sensing systems strongly suggests that regulation in accordance with cell density is important for the success of microbes in many environments (see references 25 and 95 for reviews).Cell density-dependent regulatory networks in microorganisms generally control processes that involve cell-cell interactions, such as group motility (10, 37) and the formation of multicellular structures (67,93,95). In a wide array of environmental and medically relevant bacteria, the development, maintenance, and dispersion of multicellular, surface-associated biofilms are in part controlled by quorum-sensing regulatory pathways (for reviews, see references 67 and 93). The uptake of extracellular DNA is often regulated in accordance with cell density presumably to enhance the chances of taking up DNA from closely related strains. For some bacteria, a link between the competence and biofilm formation has been established (69, 93). Both pathogens and symbionts that live in association with plant or animal hosts often use quorum sensing to regulate factors involved in microbe-host interactions (20,86,96). Quorum-sensing regulation may allow host-associated microbes to delay detection until an effective population has formed in the appropriate niche within the host.Recently, it has become apparent that fungi, like bacteria, also use quorum regulation to affect population-level behaviors such as biofilm formation and pathogenesis. Considering the extent to which quorum-sensing regulation controls important processes in many distantly related bacterial genera, it is not surprising that cell density-dependent regulation also appears to be prevalent in diverse fungal species. Because fungal quorum sensing has been most extensively studied in Candida albicans, a dimorphic opportunistic pathogen, the majority of this review focuses on the details of quorum-sensing regulation in this fungus. A discussion of other fungi that appear to use quorum-sensing regulation and the identities of other known fungal signaling molecules are presented, and potential connections between mating in fungi and cell density-dependent regulation are explored. The review will conclude with points relating to the ecology of quorum sensing and a discussion of quorum-sensing networks as potential targets for antifungal therapies.

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“…In a similar way it further regulates oxidative stress response of C. albicans (Deveau et al 2010). Farnesol was shown contributing to the increased resistance of C. albicans populations after contact to higher levels of reactive oxygen species (ROS) (Westwater et al 2005). Extracellular ROS are produced by several organisms and, accordingly, effective defending strategies are vitally important for competing fungal species.…”

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confidence: 99%