Combining ChIP-chip and Expression Profiling to Model the MoCRZ1 Mediated Circuit for Ca2+/Calcineurin Signaling in the Rice Blast Fungus

Abstract

Significant progress has been made in defining the central signaling networks in many organisms, but collectively we know little about the downstream targets of these networks and the genes they regulate. To reconstruct the regulatory circuit of calcineurin signal transduction via MoCRZ1, a Magnaporthe oryzae C2H2 transcription factor activated by calcineurin dephosphorylation, we used a combined approach of chromatin immunoprecipitation - chip (ChIP-chip), coupled with microarray expression studies. One hundred forty genes were identified as being both a direct target of MoCRZ1 and having expression concurrently differentially regulated in a calcium/calcineurin/MoCRZ1 dependent manner. Highly represented were genes involved in calcium signaling, small molecule transport, ion homeostasis, cell wall synthesis/maintenance, and fungal virulence. Of particular note, genes involved in vesicle mediated secretion necessary for establishing host associations, were also found. MoCRZ1 itself was a target, suggesting a previously unreported autoregulation control point. The data also implicated a previously unreported feedback regulation mechanism of calcineurin activity. We propose that calcium/calcineurin regulated signal transduction circuits controlling development and pathogenicity manifest through multiple layers of regulation. We present results from the ChIP-chip and expression analysis along with a refined model of calcium/calcineurin signaling in this important plant pathogen.

Calcineurin-Crz1 Signaling in Lower Eukaryotes

“…From the ChIP-chip analysis, 346 putative Crz1 binding partners could be identified. In the corresponding microarray analysis, 140 genes were found to be Crz1 dependent and these were all also identified in the ChIP-chip assay (63). Furthermore, Taken together, these expression analyses show that Crz1 regulates between ϳ30 and ϳ200 genes in the different species (the data for A. fumigatus are so far an exception).…”

“…A very elegant study to identify Crz1-dependent genes has been done in the rice blast fungus Magnaporthe oryzae (63). The authors used a combined approach of chromatin immunoprecipitation with microarray technology (ChIP-chip) and microarray analyses.…”

The Genomes of Three Uneven Siblings: Footprints of the Lifestyles of Three Trichoderma Species

“…The homeostasis of Ca 2ϩ in the cell is essential for all living organisms (823), and its intracellular levels reflect environmental changes (824). In fungi, calcium is involved in growth and tip orientation, metabolism, circadian clock regulation, pathogenicity, and differentiation processes (773,(825)(826)(827)(828)(829)(830). Levels of calcium also affect cellulase production in Trichoderma (831).…”

VdCrz1 is involved in microsclerotia formation and required for full virulence in Verticillium dahliae

“…Genes regulated by Crz1 have been identified in some fungi, such as in A. fumigatus (Karababa et al, 2006;Kim et al, 2010;Soriani et al, 2008Soriani et al, , 2010Yoshimoto et al, 2002). Surprisingly, only two of the genes regulated by Crz1 are shared among M. oryzae, S. cerevisiae, and A. fumigatus, which might indicate the divergent evolution of the genes regulated by Crz1 in response to the unique conditions faced by each species (Kim et al, 2010).…”