Calcineurin Signaling in Fungal Pathogenesis

Calcineurin is a calcium-activated serine/threonine phosphatase that serves as a master regulator of stress responses and virulence in a wide range of human fungal pathogens. By dephosphorylating key substrates, it controls cell wall integrity, thermotolerance, morphogenetic transitions and ion homeostasis under host-relevant conditions. A central effector of this pathway is the Crz1 transcription factor, whose nuclear translocation triggers expression of genes involved in cell wall remodelling, calcium transport and adaptation to hostile environments. Beyond transcriptional control, calcineurin localises to ribonucleoprotein granules to influence mRNA stability and translation, illustrating a branched signalling network. Because fungal calcineurin shares core features with its mammalian counterpart, direct inhibitors such as FK506 and cyclosporine A are immunosuppressive. Recent efforts have thus focused on dissecting fungal-specific structural motifs and combining calcineurin blockers with existing antifungals to enhance specificity and overcome resistance. These advances underscore the pathway’s global significance as a drug target and its practical applications in combating invasive and drug-resistant fungal infections.

Research from Nature Portfolio

High-resolution crystal structures of fungal calcineurin complexes with FK506 and the FK506-binding protein (FKBP12) from major human pathogens revealed subtle conformational differences in surface loops compared with the mammalian enzyme. By pinpointing a phenylalanine residue unique to fungal FKBP12, researchers engineered an FK506 analogue bearing a C22 acetohydrazine substitution that markedly reduces immunosuppression yet retains broad-spectrum antifungal efficacy in murine models of invasive infection. This structure-guided strategy offers a blueprint for next-generation calcineurin inhibitors that selectively target fungal virulence mechanisms without compromising host immunity.

Calcineurin Signaling in Fungal Pathogenesis publication trend

The graph below shows the total number of articles in calcineurin signaling in fungal pathogenesis across all publications each year (not limited to Nature Index journals).

Technical terms

Calcineurin: A Ca²⁺/calmodulin-dependent protein phosphatase that mediates fungal stress responses and virulence.

Crz1: A calcineurin-regulated transcription factor that, upon dephosphorylation, drives expression of genes for cell wall integrity and ion homeostasis.

FK506: Also known as tacrolimus; a small-molecule calcineurin inhibitor that forms a complex with FKBP12, blocking phosphatase activity and immune signalling.

FKBP12: A peptidyl-prolyl isomerase that binds immunosuppressive drugs (FK506, rapamycin) to assemble a complex that inhibits calcineurin.

References

1. Calcineurin: The Achilles’ heel of fungal pathogens. PLOS Pathogens (2023).
2. Enhanced fungal specificity and in vivo therapeutic efficacy of a C-22-modified FK520 analog against C. neoformans. mBio (2023).
3. Harnessing calcineurin-FK506-FKBP12 crystal structures from invasive fungal pathogens to develop antifungal agents. Nature Communications (2019).
4. Elucidation of the calcineurin-Crz1 stress response transcriptional network in the human fungal pathogen Cryptococcus neoformans. PLOS Genetics (2017).
5. Calcineurin Targets Involved in Stress Survival and Fungal Virulence. PLOS Pathogens (2016).