Transcriptional responses to pathogens in Caenorhabditis elegans.

Evolutionarily conserved signaling pathways, such as the p38 and ERK MAPK pathways, the TGF-beta pathway, and the insulin-signaling pathway are required for resistance to pathogens in Caenorhabditis elegans. Recent microarray expression profiling studies have identified both candidate immune effector genes which may recognize and eliminate microbial pathogens as well as uncharacterized gene classes that are broadly induced in response to pathogen. Comparative analysis of these microarray studies is suggestive of basal versus induced components of the ancient innate immune response in C. elegans. In particular, whereas the PMK-1 p38 MAPK pathway regulates genes that are induced by pathogen, the Forkhead family transcription factor DAF-16 confers pathogen resistance through the regulation of genes that are non-overlapping with pathogen-induced genes.