PubMed:27927200 JSONTXT

{"project":"PubMed_Structured_Abstracts","denotations":[{"id":"T1","span":{"begin":148,"end":468},"obj":"BACKGROUND"},{"id":"T2","span":{"begin":478,"end":1005},"obj":"RESULTS"},{"id":"T3","span":{"begin":1019,"end":1526},"obj":"CONCLUSIONS"}],"text":"Tribbles ortholog NIPI-3 and bZIP transcription factor CEBP-1 regulate a Caenorhabditis elegans intestinal immune surveillance pathway.\nBACKGROUND: Many pathogens secrete toxins that target key host processes resulting in the activation of immune pathways. The secreted Pseudomonas aeruginosa toxin Exotoxin A (ToxA) disrupts intestinal protein synthesis, which triggers the induction of a subset of P. aeruginosa-response genes in the nematode Caenorhabditis elegans.\nRESULTS: We show here that one ToxA-induced C. elegans gene, the Tribbles pseudokinase ortholog nipi-3, is essential for host survival following exposure to P. aeruginosa or ToxA. We find that NIPI-3 mediates the post-developmental expression of intestinal immune genes and proteins and primarily functions in parallel to known immune pathways, including p38 MAPK signaling. Through mutagenesis screening, we identify mutants of the bZIP C/EBP transcription factor cebp-1 that suppress the hypersusceptibility defects of nipi-3 mutants.\nCONCLUSIONS: NIPI-3 is a negative regulator of CEBP-1, which in turn negatively regulates protective immune mechanisms. This pathway represents a previously unknown innate immune signaling pathway in intestinal epithelial cells that is involved in the surveillance of cellular homeostasis. Because NIPI-3 and CEBP-1 are also essential for C. elegans development, NIPI-3 is analogous to other key innate immune signaling molecules such as the Toll receptors in Drosophila that have an independent role during development."}