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[Olfactory receptors expressed in various non-olfactory tissues.]

Sayoko Ihara1, Kazushige Touhara1

  • 1Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Japan.

Clinical Calcium
|July 28, 2018
PubMed

Insights

Olfactory receptors (ORs), typically for smell, are found in other tissues, regulating functions like breathing and gut serotonin release. These ectopic ORs sense internal chemical cues, highlighting their broader physiological roles beyond olfaction.

Area of Science:

  • Physiology
  • Genetics
  • Molecular Biology

Background:

  • Olfactory receptor (OR) genes form the largest gene family in mammals.
  • ORs are expressed in both olfactory and various non-olfactory tissues.
  • Previous research on ectopic OR functions relied heavily on in vitro studies.

Purpose of the Study:

  • To investigate the physiological roles of ectopically expressed olfactory receptors outside the olfactory system.
  • To explore the mechanisms by which non-olfactory ORs detect internal environmental cues.
  • To understand the tissue-specific functions modulated by these ectopic ORs.

Main Methods:

  • Analysis of OR knockout mice models.
  • In vitro experiments using cultured cells and tissues (mentioned as prior work).
  • Physiological assessments of breathing regulation and gut hormone release.

Main Results:

  • An OR in the carotid body senses hypoxia, regulating breathing.
  • An OR in enterochromaffin (EC) cells detects microbial metabolites, modulating serotonin release.
  • These findings demonstrate in vivo functions of ectopic ORs in non-olfactory tissues.

Conclusions:

  • Ectopically expressed ORs function as chemosensors for the internal environment.
  • These receptors play critical roles in tissue-specific physiological regulation beyond olfaction.
  • Further research is needed to elucidate the functions of ORs in other non-olfactory tissues.

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