mir-67 regulates P. aeruginosa avoidance behavior in C. elegans.

Pathogen avoidance behaviors are found throughout the animal kingdom and are important for animal's survival in nature. As a free-living nematode, C. elegans is exposed to a variety of microorganisms, including toxic or pathogenic bacteria, in soil. C. elegans can develop efficient avoidance responses to pathogenic bacteria to minimize the infection risk. However, the role of microRNAs (miRNAs) in pathogen avoidance in C. elegans remains unclear. In this report, we showed that the miRNA mir-67 was involved in a behavioral avoidance response to P. aeruginosa PA14. Exposure to P. aeruginosa PA14 induced the expression of mir-67 in worms. mir-67(n4899) mutants exhibited a reduced ability to avoid P. aeruginosa PA14. By combining quantitative proteomic analysis with miRNA target prediction algorithms, we identified SAX-7/L1CAM, which is transmembrane cell adhesion receptor molecule, as the target of mir-67. Silencing of sax-7 by RNAi on mir-67 mutants rescued avoidance behavioral. Our data demonstrate that the mir-67-SAX-7 pathway modulate the behavioral avoidance response to pathogens, thus providing a new perspective in the role of miRNAs in host-microbe interactions.