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Learning and Long-term Memory

開催日 2014/9/13
時間 14:00 - 15:00
会場 Poster / Exhibition(Event Hall B)

Analysis of downstream signaling factors of the TIR-1/JNK-1 pathway for forgetting in C.elegans

  • P3-208
  • 北園 智弘 / Tomohiro Kitazono:1 井上 明俊 / Akitoshi Inoue:1 石原 健 / Takeshi Ishihara:1,2 
  • 1:九州大院・システム生命・システム生命 / Dept of Sys Life Sci, Kyushu Univ, Fukuoka, Japan 2:九州大院・理・生物 / Fac. of Sci., Dept. of Biol., Kyushu Univ., Fukuoka 

Forgetting is important for animals to avoid memory overflow and interferences between old and new memories, and the molecular mechanisms of the forgetting are still unclear. To elucidate the mechanisms of forgetting, we used one of the behavioral plasticity, the olfactory adaptation in C.elegans as a simple model of memory. We previously showed that the mutants of TIR-1, a p38 MAPK adaptor protein, and its downstream signaling pathway (TIR-1/JNK-1 pathway) exhibit prolonged retention of the olfactory adaptation to diacetyl and isoamylalcohol, which are odorants sensed by AWA and AWC sensory neurons respectively. Our genetic analysis showed that the TIR-1/JNK-1 pathway accelerate forgetting by facilitating the release of the forgetting signals from AWC sensory neurons.
In this study, to identify downstream components of the TIR-1/JNK-1 pathway including the forgetting signals, we screened suppressor mutants of a gain of function mutants of tir-1 (ok1052). ok1052 mutants exhibit fast forgetting of the olfactory adaptation probably because the forgetting signals are excessively released in ok1052 mutants. By the suppressor screening of ok1052 mutants, we isolated 71 independent mutants, which showed the prolonged retention of the olfactory adaptation to diacetyl. Based on behavioral analyses, we revealed that these mutants could be classified into two groups; one group showed the prolonged retention of the olfactory adaptation only to diacetyl and another group showed it not only to diacetyl but also to isoamylalcohol. This result suggests that there may be partially different signaling pathway in the forgetting of the olfactory adaptation to these two odorants. Furthermore, some strains also showed the prolonged retention of the salt chemotaxis learning, which is one of the associative learning in C. elegans. To identify the responsible genes of those suppressor mutants, we carried out the whole genome sequencing analysis and single nucleotide polymorphism mapping of mutant strains, and found some novel downstream components of downstream of the TIR-1/JNK-1 pathway. This study enables us to provide new insights on the regulatory mechanisms of forgetting.

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