Biology subjects

Calise, D. G.

Publications and source records attributed to Calise, D. G..

3 recordsLinked to original sources

bioRxiv2026

The Aspergillus fumigatus C2-Domain Protein SppA is required for septal integrity and alters susceptibility to echinocandins and neutrophil killing during infection

Aspergillus fumigatus is a major opportunistic fungal pathogen whose ability to maintain hyphal integrity and withstand host defenses is critical for virulence. Septal pores, which connect hyphal compartments, are dynamically regulated to preserve cellular integrity under stress, yet the molecular components governing this process remain incompletely defined. Here, we identify and characterize a septal pore-associated protein, SppA, and demonstrate its essential role in maintaining septal integrity in A. fumigatus. We show that expression of SppA is positively regulated by the transcription factor ZfpA and is induced in response to the cell wall-targeting antifungal caspofungin. Deletion of sppA resulted in defective septal organization and increased susceptibility to hyphal damage. The mutant exhibited heightened sensitivity to cell wall-targeting antifungal agents, indicating a role in cell wall stress tolerance. In a zebrafish model of invasive aspergillosis, loss of SppA significantly attenuated virulence which was abrogated in neutrophil-deficient zebrafish. Further, the mutant strain displayed increased susceptibility to killing by primary human neutrophils, suggesting that proper septal pore formation contributes to fungal survival during host immune attack. Together, our findings establish SppA as a critical determinant of septal integrity, antifungal tolerance, and pathogenicity in A. fumigatus, and position it as part of a ZfpA-regulated, caspofungin-responsive pathway that supports fungal survival during stress and infection. Author SummaryAspergillus fumigatus is a common environmental mold that can cause life-threatening infections in people with weakened immune systems. For successful invasion of host tissue, the fungus requires the ability to protection sections of its hyphae from cell wall targeting antifungals and host immune cell attack by closing septal (cross wall) pores distributed throughout hyphal strands. We have identified an A. fumigatus protein, SppA, required for proper septal pore closure. Loss of SppA reduces the ability of hyphae to withstand treatment with antifungals and the ability of A. fumigatus to cause disease in a zebrafish infection model. The SppA mutant was particularly susceptible to killing by neutrophils, key immune cells that help control fungal infections. Our findings reveal an important mechanism that helps A. fumigatus survive environmental and host-imposed stresses and highlight septal pore regulation as a potential target for future antifungal strategies.

microbiology↗

bioRxiv2023

A network-based model of Aspergillus fumigatus elucidates regulators of development and defensive natural products of an opportunistic pathogen

Aspergillus fumigatus is a notorious pathogenic fungus responsible for various harmful, sometimes lethal, diseases known as aspergilloses. Understanding the gene regulatory networks that specify the expression programs underlying this fungus diverse phenotypes can shed mechanistic insight into its growth, development, and determinants of pathogenicity. We used eighteen RNA-seq datasets (seventeen publicly available and one previously unpublished) of Aspergillus fumigatus to construct a comprehensive gene regulatory network resource. Our resource, named GRAsp (Gene Regulation of Aspergillus fumigatus), was able to recapitulate known regulatory pathways such as response to hypoxia, iron and zinc homeostasis, and secondary metabolite synthesis. Further, GRAsp was experimentally validated in two cases: one in which GRAsp accurately identified an uncharacterized transcription factor negatively regulating the production of the virulence factor gliotoxin and another where GRAsp revealed the bZip protein, AtfA, as required for fungal responses to microbial signals known as lipo-chitooligosaccharides. Our work showcases the strength of using network-based approaches to generate new hypotheses about regulatory relationships in Aspergillus fumigatus. We also unveil an online, user-friendly version of GRAsp available to the Aspergillus research community.

systems biology↗

bioRxiv2023

Aspergillus fumigatus transcription factor ZfpA regulates hyphal development and alters susceptibility to antifungals and neutrophil killing during infection

Hyphal growth is essential for host colonization during Aspergillus infection. The transcription factor ZfpA regulates A. fumigatus hyphal development including branching, septation, and cell wall composition. However, how ZfpA affects fungal growth and susceptibility to host immunity during infection has not been investigated. Here, we use the larval zebrafish-Aspergillus infection model and primary human neutrophils to probe how ZfpA affects A. fumigatus pathogenesis and response to antifungal drugs in vivo. ZfpA deletion promotes fungal clearance and attenuates virulence in wild-type hosts and this virulence defect is abrogated in neutrophil-deficient zebrafish. ZfpA deletion also increases susceptibility to human neutrophils ex vivo while overexpression impairs fungal killing. Overexpression of ZfpA confers protection against the antifungal caspofungin by increasing chitin synthesis during hyphal development, while ZfpA deletion reduces cell wall chitin and increases caspofungin susceptibility in neutrophil-deficient zebrafish. These findings suggest a protective role for ZfpA activity in resistance to the innate immune response and antifungal treatment during A. fumigatus infection. Author SummaryAspergillus fumigatus is a common environmental fungus that can infect immunocompromised people and cause a life-threatening disease called invasive aspergillosis. An important step during infection is the development of A. fumigatus filaments known as hyphae. A. fumigatus uses hyphae to acquire nutrients and invade host tissues, leading to tissue damage and disseminated infection. In this study we report that a regulator of gene transcription in A. fumigatus called ZfpA is important for hyphal growth during infection. We find that ZfpA activity protects the fungus from being killed by innate immune cells and decreases the efficacy of antifungal drugs during infection by regulating construction of the cell wall, an important protective layer for fungal pathogens. Our study introduces ZfpA as an important genetic regulator of stress tolerance during infection that protects A. fumigatus from the host immune response and antifungal drugs.

microbiology↗