Calcium Signaling Pathway Plays an Important Role in Fungal Virulence in Plants and Humans

The Ca²⁺ dependent signaling pathway plays an important role in cellular development and metabolism. Previous studies have shown that Ca²⁺/calcineurin regulated signal transduction circuits control development and pathogenicity of Magnaporthe oryzae, a causing agent of rice blast. MoCRZ1 (M. oryzae Calcineurin Responsive Zinc Finger) activated by calcineurin dephosphorylation, acts as a downstream regulator in Calcium-dependent signaling pathway in this fungus. MoCRZ1 null mutant showed reduced virulence and impaired growth in the presence of Calcium. Research has been down to identify target genes that are regulated by MoCRZ1 by ChIP-chip and verified by microarray. Interestingly, in Aspergillus fumigatus, a primary and opportunistic pathogen as well as a major allergen that is readily isolated from human habitats, CRZA (A. fumigatus Crz1 homolog) acts in a similar pattern as MoCRZ1 in this fungus. The △crzA mutant showed less cellular tolerance to heat and ion, loss of virulence and also altered expression of calcium transporter mRNAs under high concentrations of calcium. ChIP-sequencing was hired to identify target genes regulated by CrzA as well as its binding motif. CrzA bound DNA fragments from eGFP tagged strain was immunoprecipitated with antiGFP antibody and sequencing by Illumia. Enriched short reads were aligned to the reference genome to identify CrzA binding sites and corresponding genes by removing background noise.  Total 102 genes were identified, annotated and classified. Amazingly, by comparing with M. oryzae MCRZ1 regulated genes, these two different fungi showed a common regulatory circuits pattern, which can serve as a model for studying other organisms.