title: Mutants in Drosophila TRPC channels reduce olfactory sensitivity to carbon dioxide.
abstract: BACKGROUND
  Members of the canonical Transient Receptor Potential (TRPC) class of cationic channels function downstream of Gαq and PLCβ in Drosophila photoreceptors for transducing visual stimuli. Gαq has recently been implicated in olfactory sensing of carbon dioxide (CO(2)) and other odorants. Here we investigated the role of PLCβ and TRPC channels for sensing CO(2) in Drosophila.
  
  
  RESULTS
  Through behavioral assays it was demonstrated that Drosophila mutants for plc21c, trp and trpl have a reduced sensitivity for CO(2). Immuno-histochemical staining for TRP, TRPL and TRPγ indicates that all three channels are expressed in Drosophila antennae including the sensory neurons that express CO(2) receptors. Electrophysiological recordings obtained from the antennae of protein null alleles of TRP (trp(343)) and TRPL (trpl(302)), showed that the sensory response to multiple concentrations of CO(2) was reduced. However, trpl(302); trp(343) double mutants still have a residual response to CO(2). Down-regulation of TRPC channels specifically in CO(2) sensing olfactory neurons reduced the response to CO(2) and this reduction was obtained even upon down-regulation of the TRPCs in adult olfactory sensory neurons. Thus the reduced response to CO(2) obtained from the antennae of TRPC RNAi strains is not due to a developmental defect.
  
  
  CONCLUSIONS
  These observations show that reduction in TRPC channel function significantly reduces the sensitivity of the olfactory response to CO(2) concentrations of 5% or less in adult Drosophila. It is possible that the CO(2) receptors Gr63a and Gr21a activate the TRPC channels through Gαq and PLC21C.
authors.affiliation: National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, Karnataka, India.
authors.forename: Farhath
authors.initials: F
authors.lastname: Badsha
authors.forename: Pinky
authors.initials: P
authors.lastname: Kain
authors.forename: Sunil
authors.initials: S
authors.lastname: Prabhakar
authors.forename: Susinder
authors.initials: S
authors.lastname: Sundaram
authors.forename: Raghu
authors.initials: R
authors.lastname: Padinjat
authors.forename: Veronica
authors.initials: V
authors.lastname: Rodrigues
authors.forename: Gaiti
authors.initials: G
authors.lastname: Hasan
mesh_terms: D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism* / Q000494:pharmacology; D004330:Drosophila / Q000235:genetics / Q000502:physiology; D029721:Drosophila Proteins / Q000378:metabolism / Q000502:physiology; D005786:Gene Expression Regulation; D009154:Mutation; D009833:Olfactory Pathways / Q000378:metabolism / Q000502:physiology*; D054799:Phospholipase C beta / Q000235:genetics / Q000378:metabolism; D017956:Photoreceptor Cells, Invertebrate / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D011984:Sensory Receptor Cells / Q000378:metabolism; D050052:TRPC Cation Channels / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D014785:Vision, Ocular
chemical_list: D029721:Drosophila Proteins; C516369:Gr21a protein, Drosophila; C516368:Gr63a protein, Drosophila; D011956:Receptors, Cell Surface; D050052:TRPC Cation Channels; C054079:carbon dioxide receptor; D002245:Carbon Dioxide; D054799:Phospholipase C beta