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Cellular & molecular Ca 2+ microdomains in olfactory cilia support low signaling amplification of odor transduction
Author(s) -
Castillo Karen,
Restrepo Diego,
Bacigalupo Juan
Publication year - 2010
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.2010.07393.x
Subject(s) - cyclic nucleotide gated ion channel , transduction (biophysics) , cilium , odor , biophysics , olfactory epithelium , signal transduction , microbiology and biotechnology , chemistry , olfaction , visual phototransduction , ion channel , olfactory system , biology , biochemistry , neuroscience , cyclic nucleotide , receptor , nucleotide , gene , retinal
Signal transduction depends critically on the spatial localization of protein constituents. A key question in odor transduction is whether chemotransduction proteins organize into discrete molecular complexes throughout olfactory cilia or distribute homogeneously along the ciliary membrane. Our recordings of Ca 2+ changes in individual cilia with unprecedented spatial and temporal resolution, by the use of two‐photon microscopy, provide solid evidence for Ca 2+ microdomains (transducisomes). Dissociated frog olfactory neurons were preloaded with caged‐cAMP and fluo‐4 acetoxymethyl ester probe Ca 2+ indicator. Ca 2+ influx through cyclic nucleotide‐gated (CNG) channels was evoked by uniformly photoreleasing cAMP, while ciliary Ca 2+ was measured. Discrete fluorescence events were clearly resolved. Events were missing in the absence of external Ca 2+ , consistent with the absence of internal Ca 2+ sources. Fluorescence events at individual microdomains resembled single‐CNG channel fluctuations in shape, mean duration and kinetics, indicating that transducisomes typically contain one to three CNG channels. Inhibiting the Na + /Ca 2+ exchanger or the Ca 2+ ‐ATPase prolonged the decay of evoked intraciliary Ca 2+ transients, supporting the participation of both transporters in ciliary Ca 2+ clearance, and suggesting that both molecules localize close to the CNG channel. Chemosensory transducisomes provide a physical basis for the low amplification and for the linearity of odor responses at low odor concentrations.