title: Drosophila TRPA1 channel is required to avoid the naturally occurring insect repellent citronellal.
abstract: Plants produce insect repellents, such as citronellal, which is the main component of citronellal oil. However, the molecular pathways through which insects sense botanical repellents are unknown. Here, we show that Drosophila use two pathways for direct avoidance of citronellal. The olfactory coreceptor OR83b contributes to citronellal repulsion and is essential for citronellal-evoked action potentials. Mutations affecting the Ca(2+)-permeable cation channel TRPA1 result in a comparable defect in avoiding citronellal vapor. The TRPA1-dependent aversion to citronellal relies on a G protein (Gq)/phospholipase C (PLC) signaling cascade rather than direct detection of citronellal by TRPA1. Loss of TRPA1, Gq, or PLC causes an increase in the frequency of citronellal-evoked action potentials in olfactory receptor neurons. Absence of the Ca(2+)-activated K(+) channel (BK channel) Slowpoke results in a similar impairment in citronellal avoidance and an increase in the frequency of action potentials. These results suggest that TRPA1 is required for activation of a BK channel to modulate citronellal-evoked action potentials and for aversion to citronellal. In contrast to Drosophila TRPA1, Anopheles gambiae TRPA1 is directly and potently activated by citronellal, thereby raising the possibility that mosquito TRPA1 may be a target for developing improved repellents to reduce insect-borne diseases such as malaria.
authors.affiliation: Department of Biological Chemistry, Center for Sensory Biology, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: Young
authors.initials: Y
authors.lastname: Kwon
authors.forename: Sang Hoon
authors.initials: SH
authors.lastname: Kim
authors.forename: David S
authors.initials: DS
authors.lastname: Ronderos
authors.forename: Youngseok
authors.initials: Y
authors.lastname: Lee
authors.forename: Bradley
authors.initials: B
authors.lastname: Akitake
authors.forename: Owen M
authors.initials: OM
authors.lastname: Woodward
authors.forename: William B
authors.initials: WB
authors.lastname: Guggino
authors.forename: Dean P
authors.initials: DP
authors.lastname: Smith
authors.forename: Craig
authors.initials: C
authors.lastname: Montell
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000080462:Acyclic Monoterpenes; D000447:Aldehydes / Q000494:pharmacology*; D000818:Animals; D000852:Anopheles / Q000187:drug effects / Q000378:metabolism; D001522:Behavior, Animal; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000187:drug effects / Q000378:metabolism; D005260:Female; D007302:Insect Repellents / Q000494:pharmacology*; D007473:Ion Channels; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000378:metabolism; D008297:Male; D039821:Monoterpenes / Q000494:pharmacology*; D000074025:TRPA1 Cation Channel; D050052:TRPC Cation Channels / Q000235:genetics / Q000378:metabolism*
chemical_list: D000080462:Acyclic Monoterpenes; D000447:Aldehydes; D029721:Drosophila Proteins; D007302:Insect Repellents; D007473:Ion Channels; D051036:Large-Conductance Calcium-Activated Potassium Channels; D039821:Monoterpenes; D000074025:TRPA1 Cation Channel; D050052:TRPC Cation Channels; C475684:TrpA1 protein, Drosophila; C108217:citronellal
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