Expression of cGMP signaling elements in the Grueneberg ganglion |
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Authors: | Joerg Fleischer Katharina Mamasuew Heinz Breer |
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Institution: | (1) Institute of Physiology, University of Hohenheim, Garbenstrasse 30, 70599 Stuttgart, Germany |
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Abstract: | The Grueneberg ganglion (GG) is a cluster of neurons localized to the vestibule of the anterior nasal cavity. Based on axonal
projections to the olfactory bulb of the brain, as well as expression of olfactory receptors and the olfactory marker protein,
it is considered a chemosensory subsystem. Recently, it was observed that in mice, GG neurons respond to cool ambient temperatures.
In mammals, coolness-induced responses in highly specialized neuronal cells are supposed to rely on the ion channel TRPM8,
whereas in thermosensory neurons of the nematode worm Caenorhabditis elegans, detection of environmental temperature is mainly mediated by cyclic guanosine monophosphate (cGMP) pathways, in which cGMP
is generated by transmembrane guanylyl cyclases. To unravel the molecular mechanisms underlying coolness-induced responses
in GG neurons, potential expression of TRPM8 in the murine GG was investigated; however, no evidence was found that this ion
channel is present in the GG. By contrast, a substantial number of GG neurons was observed to express the transmembrane guanylyl
cyclase subtype GC-G. In the nose, GC-G expression appears to be confined to the GG since it was not detectable in other nasal
compartments. In the GG, coolness-stimulated responses are only observed in neurons characterized by the expression of the
olfactory receptor V2r83. Interestingly, expression of GC-G in the GG was found in this V2r83-positive subpopulation but not
in other GG neurons. In addition to GC-G, V2r83-positive GG cells also co-express the phosphodiesterase PDE2A. Thus, in summary,
coolness-sensitive V2r83-expressing GG neurons are endowed with a cGMP cascade which might underlie thermosensitivity of these
cells, similar to the cGMP pathway mediating thermosensation in neurons of C. elegans.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
J. Fleischer and K. Mamasuew contributed equally to this work. |
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Keywords: | Guanylyl cyclase GC-G Olfaction Phosphodiesterase Thermosensory TRPM8 |
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