scholarly journals Role for Endosomal and Vacuolar GTPases in Candida albicans Pathogenesis

2009 ◽  
Vol 77 (6) ◽  
pp. 2343-2355 ◽  
Author(s):  
Douglas A. Johnston ◽  
Karen E. Eberle ◽  
Joy E. Sturtevant ◽  
Glen E. Palmer
Keyword(s):  
Candida Albicans ◽  
Stress Resistance ◽  
Double Mutant ◽  
Hyphal Growth ◽  
Filamentous Growth ◽  
Rab Gtpases ◽  
Fungal Cell ◽  
Cellular Stresses ◽  
Vacuole Biogenesis

ABSTRACT The vacuole has crucial roles in stress resistance and adaptation of the fungal cell. Furthermore, in Candida albicans it has been observed to undergo dramatic expansion during the initiation of hyphal growth, to produce highly “vacuolated” subapical compartments. We hypothesized that these functions may be crucial for survival within the host and tissue-invasive hyphal growth. We also considered the role of the late endosome or prevacuole compartment (PVC), a distinct organelle involved in vacuolar and endocytic trafficking. We identified two Rab GTPases, encoded by VPS21 and YPT72, required for trafficking through the PVC and vacuole biogenesis, respectively. Deletion of VPS21 or YPT72 led to mild sensitivities to some cellular stresses. However, deletion of both genes resulted in a synthetic phenotype with severe sensitivity to cellular stress and impaired growth. Both the vps21Δ and ypt72Δ mutants had defects in filamentous growth, while the double mutant was completely deficient in polarized growth. The defects in hyphal growth were not suppressed by an “active” RIM101 allele or loss of the hyphal repressor encoded by TUP1. In addition, both single mutants had significant attenuation in a mouse model of hematogenously disseminated candidiasis, while the double mutant was rapidly cleared. Histological examination confirmed that the vps21Δ and ypt72Δ mutants are deficient in hyphal growth in vivo. We suggest that the PVC and vacuole are required on two levels during C. albicans infection: (i) stress resistance functions required for survival within tissue and (ii) a role in filamentous growth which may aid host tissue invasion.

scholarly journals Paradoxical Effect of Caspofungin: Reduced Activity against Candida albicans at High Drug Concentrations

2004 ◽  
Vol 48 (9) ◽  
pp. 3407-3411 ◽  
Author(s):  
David A. Stevens ◽  
Marife Espiritu ◽  
Rachana Parmar
Keyword(s):  
Candida Albicans ◽  
Resistance Mechanisms ◽  
Paradoxical Effect ◽  
Fungal Cell ◽  
High Drug ◽  
Minimum Fungicidal Concentration ◽  
Drug Concentrations ◽  
High Concentrations ◽  
Glucan Synthesis

ABSTRACT Resistance problems with caspofungin, an echinocandin inhibitor of fungal cell wall glucan synthesis, have been rare. We noted paradoxical turbid growth of Candida albicans isolates in broth in some high (supra-MIC) concentrations. Among isolates submitted for susceptibility testing and screened at drug concentrations up to 12.5 μg/ml, the frequency was 16%. Analysis of the turbid growth indicated slowing of growth in the presence of drug but with numbers of CFU up to 72% those of drug-free controls. Clearing of growth again by the highest drug concentrations produced a quadriphasic pattern in a tube dilution series. Cells growing at high drug concentrations were not resistant on retesting but showed the paradoxical effect of the parent. Among a selected series of isolates tested at concentrations up to 50 μg/ml, an additional 53% showed a “mini-paradoxical effect”: no turbid growth but incomplete killing at high concentrations (supra-minimum fungicidal concentration). These effects were reproducible; medium dependent in extent; noted in macro- and microdilution, in the presence or absence of serum, and on agar containing drug (but not when drug concentrations were not constant, as in agar diffusion); not seen with other echinocandins and less commonly in other Candida species; and not due to destruction of drug in tubes showing the effect. Cooperative enhancement of inhibition by a second drug could eradicate the effect. We postulate that high drug concentrations derepress or activate resistance mechanisms. The abilities of subpopulations to survive at high drug concentrations could have in vivo consequences.

scholarly journals Transcriptional Regulators Cph1p and Efg1p Mediate Activation of the Candida albicans Virulence Gene SAP5 during Infection

2002 ◽  
Vol 70 (2) ◽  
pp. 921-927 ◽  
Author(s):  
Peter Staib ◽  
Marianne Kretschmar ◽  
Thomas Nichterlein ◽  
Herbert Hof ◽  
Joachim Morschhäuser
Keyword(s):  
Signal Transduction ◽  
Candida Albicans ◽  
Genetic Recombination ◽  
Hyphal Growth ◽  
Transcriptional Regulators ◽  
Infected Tissue ◽  
Mitogen Activated Protein Kinase ◽  
Signal Transduction Pathways ◽  
Aspartic Proteinases

ABSTRACT The opportunistic fungal pathogen Candida albicans can cause superficial as well as systemic infections. Successful adaptation to the different host niches encountered during infection requires coordinated expression of various virulence traits, including the switch between yeast and hyphal growth forms and secretion of aspartic proteinases. Using an in vivo expression technology that is based on genetic recombination as a reporter of gene activation during experimental candidiasis in mice, we investigated whether two signal transduction pathways controlling hyphal growth, a mitogen-activated protein kinase cascade ending in the transcriptional activator Cph1p and a cyclic AMP-dependent regulatory pathway that involves the transcription factor Efg1p, also control expression of the SAP5 gene, which encodes one of the secreted aspartic proteinases and is induced by host signals soon after infection. Our results show that both transcriptional regulators are important for SAP5 activation in vivo. SAP5 expression was reduced in a cph1 mutant, although filamentous growth in infected tissue was not detectably impaired. SAP5 expression was also reduced, but not eliminated, in an efg1 null mutant, although this strain grew exclusively in the yeast form in infected tissue, demonstrating that in contrast to in vitro conditions, SAP5 activation during infection does not depend on growth of C. albicans in the hyphal form. In a cph1 efg1 double mutant, however, SAP5 expression in infected mice was almost completely eliminated, suggesting that the two signal transduction pathways are important for SAP5 expression in vivo. The avirulence of the cph1 efg1 mutant seemed to be caused not only by the inability to form hyphae but also by a loss of expression of additional virulence genes in the host.

scholarly journals Identification of the Putative Protein Phosphatase Gene PTC1 as a Virulence-Related Gene Using a Silkworm Model of Candida albicans Infection

2008 ◽  
Vol 7 (10) ◽  
pp. 1640-1648 ◽  
Author(s):  
Nozomu Hanaoka ◽  
Yukie Takano ◽  
Kazutoshi Shibuya ◽  
Hajime Fugo ◽  
Yoshimasa Uehara ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Mouse Model ◽  
Protein Phosphatase ◽  
Protein Phosphatases ◽  
Hyphal Growth ◽  
Marker Genes ◽  
Phenotypic Traits ◽  
Putative Protein

ABSTRACT Protein phosphatases are critical for the regulation of many cellular processes. Null mutants of 21 putative protein phosphatases of Candida albicans were constructed by consecutive allele replacement using the URA3 and ARG4 marker genes. A simple silkworm model of C. albicans infection was used to screen the panel of mutants. Four null mutant (cmp1Δ, yvh1Δ, sit4Δ, and ptc1Δ) strains showed attenuated virulence in the silkworm model relative to that of control and parental strains. Three of the mutants, the cmp1Δ, yvh1Δ, and sit4Δ mutants, had previously been identified as affecting virulence in a conventional mouse model, indicating the validity of the silkworm model screen. Disruption of the putative protein phosphatase gene PTC1 of C. albicans, which has 52% identity to the Saccharomyces cerevisiae type 2C protein phosphatase PTC1, significantly reduced virulence in the silkworm model. The mutant was also avirulent in a mouse model of disseminated candidiasis. Reintroducing either of the C. albicans PTC1 alleles into the disruptant strain, using a cassette containing either allele under the control of a constitutive ACT1 promoter, restored virulence in both infection models. Characterization of ptc1Δ revealed other phenotypic traits, including reduced hyphal growth in vitro and in vivo, and reduced extracellular proteolytic activity. We conclude that PTC1 may contribute to pathogenicity in C. albicans.

scholarly journals Rac1 and Cdc42 Have Different Roles in Candida albicans Development

2006 ◽  
Vol 5 (2) ◽  
pp. 321-329 ◽  
Author(s):  
Martine Bassilana ◽  
Robert A. Arkowitz
Keyword(s):  
Candida Albicans ◽  
Plasma Membrane ◽  
G Protein ◽  
Fluorescence Recovery After Photobleaching ◽  
Hyphal Growth ◽  
Opportunistic Pathogen ◽  
Filamentous Growth ◽  
Fluorescence Recovery

ABSTRACT We investigated the role of the highly conserved G protein Rac1 in the opportunistic pathogen Candida albicans. We identified and disrupted RAC1 and show here that, in contrast to CDC42, it is not necessary for viability or serum-induced hyphal growth but is essential for filamentous growth when cells are embedded in a matrix. Rac1 is localized to the plasma membrane, yet its distribution is more homogenous than that of Cdc42, with no enrichment at the tips of either buds or hyphae. In addition, fluorescence recovery after photobleaching results indicate that Rac1 and Cdc42 have different dynamics at the membrane. Furthermore, overexpression of Rac1 does not complement Cdc42 function, and conversely, overexpression of Cdc42 does not complement Rac1 function. Thus, Rac1 and Cdc42, although highly similar to one another, have different roles in C. albicans development.

In vitro and in vivo activity of chelerythrine against Candida albicans and underlying mechanisms

2019 ◽  
Vol 14 (18) ◽  
pp. 1545-1557 ◽  
Author(s):  
Ying Gong ◽  
Siwen Li ◽  
Weixin Wang ◽  
Yiman Li ◽  
Wenli Ma ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Antifungal Activity ◽  
Calcium Concentration ◽  
Galleria Mellonella ◽  
Hyphal Growth ◽  
Drug Transporter ◽  
Antifungal Effect ◽  
Underlying Mechanisms

Aim: To evaluate whether chelerythrine (CHT) exhibited antifungal activity against Candida albicans in vitro and in vivo and to explore the underlying mechanisms. Materials & methods: Broth microdilution assay and Galleria mellonella model were used to evaluate the antifungal effect in vitro and in vivo, respectively. Mechanism studies were investigated by morphogenesis observation, Fluo-3/AM, DCFH-DA and rhodamine6G assay, respectively. Results: CHT exhibited antifungal activity against C. albicans and preformed biofilms with minimum inhibitory concentrations ranged from 2 to 16 μg/ml. Besides, CHT protected G. mellonella larvae infected by C. albicans. Mechanisms studies revealed that CHT inhibited hyphal growth, increased intracellular calcium concentration, induced accumulation of reactive oxygen species and inhibited drug transporter activity. Conclusion: CHT exhibited antifungal activity against C. albicans.

scholarly journals Candida albicans Ubiquitin and Heat Shock Factor-Type Transcriptional Factors Are Involved in 2-Dodecenoic Acid-Mediated Inhibition of Hyphal Growth

2020 ◽  
Vol 8 (1) ◽  
pp. 75
Author(s):  
Dongliang Yang ◽  
Yanling Hu ◽  
Zixin Yin ◽  
Qianru Gao ◽  
Yuqian Zhang ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Hyphal Growth ◽  
Filamentous Growth ◽  
Burkholderia Cenocepacia ◽  
Hyphal Morphogenesis ◽  
Expression Of Genes ◽  
Exogenous Addition ◽  
Diffusible Signal Factor ◽  
Factor Type ◽  
Hyphal Formation

Cis-2-dodecenoic acid (i.e., Burkholderia cenocepacia Diffusible Signal Factor, BDSF), a signaling molecule produced by Burkholderia cenocepacia but not by Candida albicans, can prevent Candida albicans hyphal formation. The mechanism by which BDSF controls the morphological switch of C. albicans is still unknown. To address this issue, we used the cDNA microarray method to investigate the differential expression of genes in C. albicans in the presence and absence of BDSF. The microarray result indicated that 305 genes were significantly different in the expression level. This included the downregulation of 75 genes and the upregulation of 230 genes. Based on the microarray data, a mutant library was screened to search for genes, once mutated, conferred insensitivity to BDSF. The results showed that the repressors (Ubi4 and Sfl1 proteins) and the activator (Sfl2 protein) of filamentous growth are involved in the BDSF regulation of hyphal morphogenesis. Ubi4, an ubiquitin polypeptide that participates in ubiquitin-mediated protein turnover, is the protein required for the degradation of Sfl2. Sfl1 and Sfl2 proteins antagonistically control C. albicans morphogenesis. In the hyphal induction condition, the amount of Ubi4 and Sfl1 protein increased rapidly with the exogenous addition of BDSF. As a result, the protein level of the activator of filamentous growth, Sfl2, decreased correspondingly, thereby facilitating the C. albicans cells to remain in the yeast form.

scholarly journals Endosomal and AP-3-Dependent Vacuolar Trafficking Routes Make Additive Contributions to Candida albicans Hyphal Growth and Pathogenesis

2010 ◽  
Vol 9 (11) ◽  
pp. 1755-1765 ◽  
Author(s):  
Glen E. Palmer
Keyword(s):  
Candida Albicans ◽  
Double Mutant ◽  
Kidney Tissue ◽  
Hyphal Growth ◽  
Endosomal Trafficking ◽  
Transcriptional Responses ◽  
Transport Pathways ◽  
Content Type ◽  
Vacuolar Protein ◽  
Vacuolar Trafficking

ABSTRACT Candida albicans mutants deficient in vacuolar biogenesis are defective in polarized hyphal growth and virulence. However, the specific vacuolar trafficking routes required for hyphal growth and virulence are unknown. In Saccharomyces cerevisiae, two trafficking routes deliver material from the Golgi apparatus to the vacuole. One occurs via the late endosome and is dependent upon Vps21p, while the second bypasses the endosome and requires the AP-3 complex, including Aps3p. To determine the significance of these pathways in C. albicans hyphal growth and virulence, aps3Δ/Δ, vps21Δ/Δ, and aps3Δ/Δ vps21Δ/Δ mutant strains were constructed. Analysis of vacuolar morphology and localization of the vacuolar protein Mlt1p suggests that C. albicans Aps3p and Vps21p mediate two distinct transport pathways. The vps21Δ/Δ mutant has a minor reduction in hyphal elongation, while the aps3Δ/Δ mutant has no defect in hyphal growth. Interestingly, the aps3Δ/Δ vps21Δ/Δ double mutant has dramatically reduced hyphal growth. Overexpression of the Ume6p transcriptional activator resulted in constitutive hyphal growth of wild-type, aps3Δ/Δ, and vps21Δ/Δ strains and formation of highly vacuolated subapical compartments. Thus, Ume6p-dependent transcriptional responses are sufficient to induce subapical vacuolation. However, the aps3Δ/Δ vps21Δ/Δ mutant formed mainly pseudohyphae that lacked vacuolated compartments. The aps3Δ/Δ strain was virulent in a mouse model of disseminated infection; the vps21Δ/Δ mutant failed to kill mice but persisted within kidney tissue, while the double mutant was avirulent and cleared from the kidneys. These results suggest that while the AP-3 pathway alone has little impact on hyphal growth or virulence, it is much more significant when endosomal trafficking is disrupted.

scholarly journals Invasive Lesions Containing Filamentous Forms Produced by a Candida albicans Mutant That Is Defective in Filamentous Growth in Culture

1999 ◽  
Vol 67 (7) ◽  
pp. 3649-3652 ◽  
Author(s):  
Perry J. Riggle ◽  
Karl A. Andrutis ◽  
Xi Chen ◽  
Saul R. Tzipori ◽  
Carol A. Kumamoto
Keyword(s):  
Candida Albicans ◽  
Double Mutant ◽  
Filamentous Growth ◽  
Standard Laboratory ◽  
Laboratory Conditions ◽  
Gnotobiotic Piglets

ABSTRACT A Candida albicans efg1 cph1 double mutant is nonfilamentous under standard laboratory conditions and avirulent in mice. However, this mutant produced filaments in the tongues of immunosuppressed gnotobiotic piglets and when embedded in agar, demonstrating that an Efg1p- and Cph1p-independent pathway for promotion of filamentous growth exists.

scholarly journals Candida albicans HWP1 gene expression and host antibody responses in colonization and disease

2006 ◽  
Vol 55 (10) ◽  
pp. 1323-1327 ◽  
Author(s):  
Julian R. Naglik ◽  
Florentia Fostira ◽  
Jasmeet Ruprai ◽  
Janet F. Staab ◽  
Stephen J. Challacombe ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Human Subjects ◽  
Oral Candidiasis ◽  
Hyphal Growth ◽  
Antibody Responses ◽  
Developmentally Regulated ◽  
Vaginal Symptoms ◽  
Oral Symptoms ◽  
Culture Negative

In vivo expression of the developmentally regulated Candida albicans hyphal wall protein 1 (HWP1) gene was analysed in human subjects who were culture positive for C. albicans and had oral symptoms (n=40) or were asymptomatic (n=29), or had vaginal symptoms (n=40) or were asymptomatic (n=29). HWP1 mRNA was present regardless of symptoms, implicating hyphal and possibly pseudohyphal forms in mucosal carriage as well as disease. As expected, in control subjects without oral symptoms (n=10) and without vaginal symptoms (n=10) who were culture negative in oral and vaginal samples, HWP1 mRNA was not detected. However, exposure to Hwp1 in healthy culture-negative controls, as well as in oral candidiasis and asymptomatic mucosal infections, was shown by the existence of local salivary and systemic adaptive antibody responses to Hwp1. The results are consistent with a role for Hwp1 in gastrointestinal colonization as well as in mucosal symptomatic and asymptomatic infections. Overall, Hwp1 and hyphal growth forms appear to be important factors in benign and invasive interactions of C. albicans with human hosts.

scholarly journals Transcriptional Response of Candida albicans upon Internalization by Macrophages

2004 ◽  
Vol 3 (5) ◽  
pp. 1076-1087 ◽  
Author(s):  
Michael C. Lorenz ◽  
Jennifer A. Bender ◽  
Gerald R. Fink
Keyword(s):  
Candida Albicans ◽  
Stress Responses ◽  
Early Phase ◽  
Large Scale ◽  
Fungal Infections ◽  
Transcriptional Response ◽  
Hyphal Growth ◽  
Phagocytic Cells ◽  
Opportunistic Fungal Pathogen

ABSTRACT The opportunistic fungal pathogen Candida albicans is both a benign gut commensal and a frequently fatal systemic pathogen. The interaction of C. albicans with the host's innate immune system is the primary factor in this balance; defects in innate immunity predispose the patient to disseminated candidiasis. Because of the central importance of phagocytic cells in defense against fungal infections, we have investigated the response of C. albicans to phagocytosis by mammalian macrophages using genomic transcript profiling. This analysis reveals a dramatic reprogramming of transcription in C. albicans that occurs in two successive steps. In the early phase cells shift to a starvation mode, including gluconeogenic growth, activation of fatty acid degradation, and downregulation of translation. In a later phase, as hyphal growth enables C. albicans to escape from the macrophage, cells quickly resume glycolytic growth. In addition, there is a substantial nonmetabolic response imbedded in the early phase, including machinery for DNA damage repair, oxidative stress responses, peptide uptake systems, and arginine biosynthesis. Further, a surprising percentage of the genes that respond specifically to macrophage contact have no known homologs, suggesting that the organism has undergone substantial evolutionary adaptations to the commensal or pathogen lifestyle. This transcriptional reprogramming is almost wholly absent in the related, but nonpathogenic, yeast Saccharomyces cerevisiae, suggesting that these large-scale and coordinated changes contribute significantly to the ability of this organism to survive and cause disease in vivo.

Sign in / Sign up

Export Citation Format

Share Document