The Aspergillus fumigatus pkcAG579R Mutant Is Defective in the Activation of the Cell Wall Integrity Pathway but Is Dispensable for Virulence in a Neutropenic Mouse Infection Model

• Published in: PloS one 2015-08, Vol.10 (8), p.e0135195
• Main Authors: Rocha, Marina Campos, Godoy, Krissia Franco de, de Castro, Patrícia Alves, Hori, Juliana Issa, Bom, Vinícius Leite Pedro, Brown, Neil Andrew, Cunha, Anderson Ferreira da, Goldman, Gustavo Henrique, Malavazi, Iran
• Format: Article
• Language: English
• Subjects: Activation; Animal models; Aspergillosis; Aspergillus fumigatus; Aspergillus nidulans; Aspergillus niger; Biosynthesis; Cell activation; Cell adhesion & migration; Cell cycle; Cell walls; Disease control; Downstream effects; Endoplasmic reticulum; Fungal infections; Fungi; Gene expression; Genomes; Homeostasis; Immunology; Infections; Integrity; Kinases; Lung diseases; MAP kinase; Mutation; Neutropenia; Opportunist infection; Phagocytosis; Protein folding; Protein kinase C; Proteins; Saccharomyces cerevisiae; Signal transduction; Signaling; Tumor necrosis factor-α; Virulence; Yard waste
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0135195

Aspergillus fumigatus is an opportunistic human pathogen, which causes the life-threatening disease, invasive pulmonary aspergillosis. In fungi, cell wall homeostasis is controlled by the conserved Cell Wall Integrity (CWI) pathway. In A. fumigatus this signaling cascade is partially characterized, but the mechanisms by which it is activated are not fully elucidated. In this study we investigated the role of protein kinase C (PkcA) in this signaling cascade. Our results suggest that pkcA is an essential gene and is activated in response to cell wall stress. Subsequently, we constructed and analyzed a non-essential A. fumigatus pkcAG579R mutant, carrying a Gly579Arg substitution in the PkcA C1B regulatory domain. The pkcAG579R mutation has a reduced activation of the downstream Mitogen-Activated Protein Kinase, MpkA, resulting in the altered expression of genes encoding cell wall-related proteins, markers of endoplasmic reticulum stress and the unfolded protein response. Furthermore, PkcAG579R is involved in the formation of proper conidial architecture and protection to oxidative damage. The pkcAG579R mutant elicits increased production of TNF-α and phagocytosis but it has no impact on virulence in a murine model of invasive pulmonary aspergillosis. These results highlight the importance of PkcA to the CWI pathway but also indicated that additional regulatory circuits may be involved in the biosynthesis and/or reinforcement of the A. fumigatus cell wall during infection.