Cited by 90Antifungal resistance and susceptibilityFungal and yeast genetics researchFungal Infections and Studies

Roles of Calcineurin and Crz1 in Antifungal Susceptibility and Virulence of Candida glabrata

Open access
Miyazaki, Taiga, Yamauchi, Shunsuke, Inamine, Tatsuo, Nagayoshi, Yosuke, Saijo, Tomomi, Izumikawa, Koichi, Seki, Masafumi, Kakeya, Hiroshi +4 more·2010·Antimicrobial Agents and Chemotherapy

Abstract

A Candida glabrata calcineurin mutant exhibited increased susceptibility to both azole antifungal and cell wall-damaging agents and was also attenuated in virulence. Although a mutant lacking the downstream transcription factor Crz1 displayed a cell wall-associated phenotype intermediate to that of the calcineurin mutant and was modestly attenuated in virulence, it did not show increased azole susceptibility. These results suggest that calcineurin regulates both Crz1-dependent and -independent pathways depending on the type of stress.

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Written from the paper’s full text.

TL;DR

Deletion of the calcineurin regulatory subunit CNB1 in *Candida glabrata* increased susceptibility to azoles and cell wall-damaging agents and attenuated virulence in mice, whereas deletion of the downstream transcription factor CRZ1 produced only an intermediate cell wall phenotype and modest virulence attenuation without increased azole susceptibility. The authors conclude that calcineurin acts through both Crz1-dependent and Crz1-independent pathways depending on the stress type.

Key findings

  • The Δcnb1 strain showed increased azole susceptibility (fluconazole MIC 4 μg/ml vs. 16 μg/ml for wild type; miconazole 0.125 vs. 0.5; itraconazole 0.5 vs. 2; voriconazole 0.125 vs. 0.25), while the Δcrz1 strain showed equal or lower susceptibility (fluconazole MIC 32 μg/ml). Neither mutant altered amphotericin B susceptibility (MIC 0.5 μg/ml for all strains).
  • Fluconazole was fungicidal for the Δcnb1 strain but not for the Δcrz1 strain, suggesting calcineurin mediates azole tolerance via a Crz1-independent pathway.
  • Both Δcnb1 and Δcrz1 had decreased micafungin tolerance; Δcnb1 also showed decreased tolerance to Congo red and calcofluor white, whereas Δcrz1 showed only moderately decreased Congo red tolerance and was unaffected by calcofluor white.
  • In a murine disseminated candidiasis model, Δcnb1-infected mice had significantly reduced fungal burden in all examined organs versus wild-type and complemented strains; Δcrz1 CFU reductions were statistically significant in kidney but not liver or spleen.

Methods

  • Genetic approach: complete deletion of the CNB1 ORF (calcineurin regulatory B subunit) and CRZ1 by one-step PCR-based gene targeting in *C. glabrata*, verified by PCR and Southern blotting, with plasmid-based complemented strains (pCgACT-PNB, pCgACT-PRZ).
  • Antifungal susceptibility testing by MIC assays using the ASTY colorimetric microdilution panel (fluconazole, miconazole, itraconazole, voriconazole, amphotericin B), plus viability assays with and without fluconazole and plate assays with micafungin, Congo red, and calcofluor white.
  • Virulence assay: groups of 10 female 8-week-old BALB/c mice infected via lateral tail vein, euthanized 7 days after injection for organ CFU determination; Kruskal-Wallis test with Dunn's posttest, P < 0.05 significant.

Limitations

  • Not stated in the paper: the authors do not include a dedicated limitations section.
  • Evident from the text: virulence was assessed in a single murine model (disseminated candidiasis, 7-day endpoint, no deaths before euthanasia), so organ CFU is the only virulence readout; the Crz1-independent calcineurin pathway is inferred from mutant phenotypes but no specific target is identified.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1128/aac.01364-09

Cites

31 of 31 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 21 cited sources checked · 0 supported · 0 flagged

  • Findingown data
    § Abstract

    The C. glabrata calcineurin mutant (Δcnb1) exhibits increased susceptibility to cell wall-damaging agents.

    “A Candida glabrata calcineurin mutant exhibited increased susceptibility to both azole antifungal and cell wall-damaging agents and was also attenuated in virulence.”
    Quote in the paperSubstantial claim
  • Findingown data
    § Abstract

    The decreased micafungin tolerance in the Δcnb1 and Δcrz1 strains was reversed in the reconstituted strains.

    “and this was reversed in the reconstituted strains (Fig. 2).”
    Quote in the paperSubstantial claim
  • Findingown data
    § Abstract

    The C. glabrata calcineurin mutant (Δcnb1) exhibits increased susceptibility to azole antifungals.

    “Although increased azole susceptibility was observed in the Δcnb1 strain”
    Quote in the paperSubstantial claim
  • Findingown data
    § Abstract

    The C. glabrata Δcrz1 mutant does not show increased azole susceptibility.

    “it did not show increased azole susceptibility.”
    • Also stated in: § Abstract · plain
      “the Δcrz1 strain displayed susceptibility levels similar to, or in some instances lower than, those of wild-type cells.”
    Quote in the paperSubstantial claim
  • Findingown data
    § Abstract

    Decreased micafungin tolerance was observed in the Δcnb1 strain compared to wild-type.

    “Decreased micafungin tolerance was observed in the Δcnb1 and Δcrz1 strains compared to that in the wild-type control”
    Quote in the paperSubstantial claim
  • May combine two claims. 4
  • Classified as probably not a substantial claim. 4
  • May combine two claims.

    Findingown data
    § Abstract

    Decreased numbers of CFU of the Δcrz1 strain were statistically significant in the kidney but not in the liver and spleen.

    “Decreased numbers of CFU of the Δcrz1 strain were statistically significant in the kidney but not in the liver and spleen.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data
    § Abstract

    The C. glabrata Δcrz1 strain exhibited increased susceptibility to micafungin and Congo red but not to calcofluor white.

    “In addition, the C. glabrata Δcrz1 strain exhibited increased susceptibility to micafungin and Congo red but not to calcofluor white.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Abstract

    The virulence of a Δcrz1 mutant is highly attenuated in Aspergillus fumigatus.

    “Although the virulence of a Δcrz1 mutant is highly attenuated in A. fumigatus (7, 29)”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [7] source

      Not checked in the free run.

    • cites [29] source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation
    § Abstract

    Azole antifungals and calcineurin inhibitors have mild synergistic effects against C. glabrata wild-type strains.

    “although it has been reported that azole antifungals and calcineurin inhibitors have mild synergistic effects against C. glabrata wild-type strains (8, 15, 22).”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [8] source

      Not checked in the free run.

    • cites [15] source

      Not checked in the free run.

    • cites [22] source

      Not checked in the free run.

  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation
    § Abstract

    Calcineurin is a heterodimer consisting of a catalytic A subunit and a Ca2+-binding regulatory B subunit, and the association between the two subunits is necessary for phosphatase activity.

    “Calcineurin is a heterodimer consisting of a catalytic A subunit and a Ca2+-binding regulatory B subunit, and the association between the two subunits is necessary for phosphatase activity (19).”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [19] source

      Not checked in the free run.

  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation
    § Abstract

    Crz1 is a downstream effector of calcineurin and is involved in azole tolerance in Candida albicans.

    “The transcription factor Crz1 is a downstream effector of calcineurin and is involved in azole tolerance in C. albicans (14, 23, 28);”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [14] source

      Not checked in the free run.

    • cites [23] source

      Not checked in the free run.

    • cites [28] source

      Not checked in the free run.

6 of 6
  • The paper relies on this without support.

    The antifungal activity of fluconazole is generally fungistatic.

    “Although the antifungal activity of fluconazole is generally fungistatic, the drug was fungicidal for the Δcnb1 strain (Fig. 1).”
  • The paper relies on this without support.

    A Crz1 homolog in C. glabrata has yet to be characterized.

    “however, a Crz1 homolog in C. glabrata has yet to be characterized.”
  • The paper relies on this without support.

    Very little is known about the calcineurin pathway in C. glabrata.

    “To date, very little is known about the calcineurin pathway in C. glabrata, although it has been reported that azole antifungals and calcineurin inhibitors have mild synergistic effects against C. glabrata wild-type strains (8, 15, 22).”
  • The paper relies on this without support.

    The involvement of calcineurin and Crz1 in virulence has not been reported in C. glabrata.

    “To date, the involvement of calcineurin and Crz1 in virulence has not been reported in C. glabrata.”
  • The paper relies on this without support.

    Growth at 37°C is a necessary prerequisite for comparing virulence levels.

    “which is a necessary prerequisite for comparing virulence levels.”
5 of 5

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Authors
Miyazaki, T., Yamauchi, S., Inamine, T., Nagayoshi, Y., Saijo, T., Izumikawa, K., Seki, M., Kakeya, H., Yamamoto, Y., Yanagihara, K., Miyazaki, Y., & Kohno, S.
Affiliations
  • Nagasaki University (JP)
  • National Institute of Infectious Diseases (JP)
Venue
Antimicrobial Agents and Chemotherapy
Published
2010-04
Volume
54
Issue
4
Pages
1639-1643
ISSN
  • 0066-4804 (ISSN-L)
  • 1098-6596
OpenAlex
W2106090528
Cited by
88
References
31
Citations by year
2026: 1 · 2025: 6 · 2024: 4 · 2023: 2 · 2022: 11 · 2021: 1 · 2020: 7 · 2019: 3 · 2018: 6 · 2017: 7 · 2016: 7 · 2015: 4 · 2014: 9 · 2013: 6 · 2012: 5
FWCI
4.13
Type
journal article
Language
en
Open access
Locations
  • Antimicrobial Agents and Chemotherapy (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
  • Nagasaki University's Academic Output SITE (Nagasaki University) (submittedVersion, cc-by-nc-nd)
Funders
  • Ministry of Education, Culture, Sports, Science and Technology (21390305)
  • Japan Society for the Promotion of Science (19790324)
Topics
  • Health Sciences › Medicine › Infectious Diseases › Antifungal resistance and susceptibility
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Fungal and yeast genetics research
  • Health Sciences › Medicine › Epidemiology › Fungal Infections and Studies
Keywords
calcineurin, Crz1, Candida glabrata, antifungal susceptibility, virulence, azole antifungals, cell wall stress, transcription factor regulation
MeSH terms
Animals, Antifungal Agents, Base Sequence, Candidiasis, DNA, Fungal, Female, Fungal Proteins, Genes, Fungal, Humans, Mice, Inbred BALB C, Microbial Sensitivity Tests, Mutation, Opportunistic Infections, Transcription Factors, Virulence, DNA Primers, Calcineurin, Drug Resistance, Fungal, Candida glabrata, Mice, In Vitro Techniques

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