title: Innate immune genes including a mucin-like gene, mul-1, induced by ionizing radiation in Caenorhabditis elegans.
abstract: The effect of radiation on the intestine has been studied for more than one hundred years. It remains unclear, however, whether this organ uses specific defensive mechanisms against ionizing radiation. The infection with  Pseudomonas aeruginosa  (PA14) in  Caenorhabditis elegans  induces up-regulation of innate immune response genes. Here, we found that exposure to ionizing radiation also induces certain innate immune response genes such as F49F1.6 (termed mul-1), clec-4, clec-67, lys-1 and lys-2 in the intestine. Moreover, pre-treatment with ionizing radiation before seeding on PA14 lawn plate significantly increased survival rate in the nematode. We also studied transcription pathway of the mul-1 in response to ionizing radiation. Induction of mul-1 gene was highly dependent on the ELT-2 transcription factor and p38 MAPK. Moreover, the insulin/IGF-1 signal pathway works to enhance induction of this gene. The mul-1 gene showed a different induction pattern from the DNA damage response gene, ced-13, which implies that the expression of this gene might be triggered as an indirect effect of radiation. Silencing of the mul-1 gene led to growth retardation after treatment with ionizing radiation. We describe the cross-tolerance between the response to radiation exposure and the innate immune system.
authors.affiliation: Graduate School of Life Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Kimura
authors.forename: Takako
authors.initials: T
authors.lastname: Takanami
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Sakashita
authors.forename: Seiichi
authors.initials: S
authors.lastname: Wada
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Higashitani
mesh_terms: D000818:Animals; D017209:Apoptosis; D017173:Caenorhabditis elegans / Q000276:immunology / Q000382:microbiology / Q000528:radiation effects*; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism; D051858:Forkhead Transcription Factors; D007113:Immunity, Innate / Q000235:genetics / Q000528:radiation effects*; D009077:Mucins / Q000235:genetics*; D021381:Protein Transport / Q000528:radiation effects; D014157:Transcription Factors / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000502:physiology
chemical_list: D029742:Caenorhabditis elegans Proteins; D051858:Forkhead Transcription Factors; D009077:Mucins; D014157:Transcription Factors; C108831:daf-16 protein, C elegans; D048051:p38 Mitogen-Activated Protein Kinases