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. Author manuscript; available in PMC: 2015 Feb 1.
Published in final edited form as: Semin Immunol. 2014 May 21;26(4):303–309. doi: 10.1016/j.smim.2014.04.005

Figure 2. Antimicrobial responses in C. elegans.

Figure 2

The central signaling modules of the antimicrobial response of the nematode are conserved MAP kinase mediated signaling cascades. Upon exposure to fungi and intestinal infection the p38 homolog PMK-1 is induced via upstream kinases NSY-1 and SEK-1 and the scaffold protein TIR-1. The receptor that activates TIR-1 is still unknown. The PMK-1 induced nuclear response is to a large extent mediated by the transcription factor ATF-7 leading to expression of putatively secreted innate immune effectors such as C-type lectins, CUB domain containing proteins and antimicrobial peptides. Another MAP kinase homolog - MPK-1/ERK, is activated during infection with Microbacterium nematophilum by upstream kinases LIN-45 and MEK-2. The transcriptional response that is triggered by MPK-1 is similar to the one mediated by PMK-1 however the exact nuclear mediator is not known. Also the TGF-beta related pathway consisting of a secreted ligand DBL-1, two membrane anchored receptors (SMA-6 and DAF-4) and three cytoplasmic signal transducers (SMA-2-4), is implicated in antimicrobial defense based on the need of its functionality for the infection survival and on gene expression profiles of respective loss of function mutants.