Abstract
Increasing evidence indicate that the expression of defense genes at the right place and the right time are regulated by host-defense transcription factors. However, the precise mechanisms of this regulation are not well understood. Homeodomain transcription factors, encoded by homeobox genes, play crucial role for the development of multicellular eukaryotes. In this study, we demonstrated that homeodomain transcription factor CEH-37 (known as OTX2 in mammals) was a key transcription factor for host defense in Caenorhabditis elegans. Meanwhile, CEH-37 acted in the intestine to protect C. elegans against pathogen infection. We further showed that the homeodomain transcription factor CEH-37 positively regulated PMK-1/ p38 MAPK activity to promote the intestinal immunity via suppression phosphatase VHP-1. Furthermore, we demonstrated that this function was conserved, because the human homeodomain transcription factor OTX2 also exhibited protective function in lung epithelial cells during Pseudomonas aeruginosa infection. Thus, our work reveal that CEH-37/OTX2 is a evolutionarily conserved transcription factor for defense against pathogen infection. The finding provides a model in which CEH-37 decreases VHP-1 phosphatase activity, allowing increased stimulation of PMK-1/p38 MAPK phosphorylation cascade in the intestine for pathogen resistance.