Transcription profiling of mouse MyD88-deficient bone marrow-derived macrophages treated with Zymosan

Innate immune pattern recognition receptors play critical roles in pathogen detection and initiation of antimicrobial responses. We and others have previously demonstrated the importance of the beta-glucan receptor Dectin-1 in the recognition of pathogenic fungi by macrophages and dendritic cells, and have elucidated some of the mechanisms by which Dectin-1 signals to coordinate the antifungal response. While Dectin-1 signals alone are sufficient to trigger phagocytosis and Src-Syk-mediated induction of antimicrobial reactive oxygen species, collaboration with Toll-like receptor (TLR)2 signaling enhances NF-kB activation and regulates cytokine production. In this study we demonstrate that Dectin-1 signaling can also directly modulate gene expression via activation of nuclear transcription of activated T cells (NFAT) transcription factors. Dectin-1 ligation by zymosan particles or live Candida albicans yeast triggers NFAT activation in macrophages and dendritic cells. Dectin-1-triggered NFAT activation plays a role in the induction of Egr2 and Egr3 transcription factors, and cyclooxygenase 2 (Cox-2). Furthermore, we show that NFAT activation regulates IL-2, IL-10 and IL-12 p70 production by zymosan-stimulated dendritic cells. These data establish NFAT activation in myeloid cells as a novel mechanism of regulation of the innate antimicrobial response. Experiment Overall Design: Bone marrow-derived macrophages deficient in MyD88 were stimulated with zymosan, and total RNA was extracted 120 minutes after stimulation for comparison to macrophages grown under the same conditions, but not stimulated.