α‐Gustducin expression in the vomeronasal organ of the mouse

Abstract

The expression of alpha-gustducin, a G protein alpha subunit involved in bitter and sweet taste transduction, was investigated in chemosensory tissues of adult mice. By immunohistochemistry, alpha gustducin was absent in the olfactory neuroepithelium. Instead, alpha gustducin was expressed in a subset of bipolar cells in the proliferative zone of the vomeronasal neuroepithelium as well as in taste buds. Northern blot analysis confirmed the presence of alpha gustducin in isolated vomeronasal organs. Moreover, immunohisto- chemistry revealed the expression of alpha gustducin in scattered cells of the nasal respiratory epithelium. These results show for the first time that alpha gustducin is expressed in chemosensory tissue outside the alimentary tract, suggesting that common transduction mechanisms could be shared by apparently unrelated chemosensory tissues.

Solitary chemoreceptor cells in the nasal cavity serve as sentinels of respiration

“…1) lining the medial (septum) and lateral walls of the anterior nasal cavity in both mice and rats. The immunoreactive cells are also present along the anteroventral edges of the anterior group of turbinates, i.e., facing the incoming airflow, and, as reported elsewhere (12,13), in the anterior ducts of the vomeronasal organ. Another way to visualize the distribution of gustducin-containing cells is by use of a transgenic mouse, where the gustducin promoter drives expression of GFP (ref.…”

“…Despite the phylogenetically wide abundance of SCCs throughout the nonmammalian vertebrates, such cells are not generally described for mammals. Three previous reports (12,13,24) describe the presence of potential SCCs in mammals, but their degree of similarity to the SCCs of aquatic anamniote vertebrates is unclear. Further, the SCC-like cells reported in mammals were limited to certain developmental stages or to restricted areas of specialized epithelia (13,24).…”

“…Three previous reports (12,13,24) describe the presence of potential SCCs in mammals, but their degree of similarity to the SCCs of aquatic anamniote vertebrates is unclear. Further, the SCC-like cells reported in mammals were limited to certain developmental stages or to restricted areas of specialized epithelia (13,24). Likewise, the presence of T2R-expressing cells in the nasal cavity was noted (11), but the nature of such cells was not described.…”

“…The nasal gustducin-expressing SCCs share features with some taste-receptor cells and with gut enteroendocrine cells. All of these chemosensory cell types express T2R receptors and gustducin, and respond to bitter-tasting substances (13,17), but are quite different from one another in terms of morphology and relationship to local tissue elements. Thus, T2R receptor molecules should not be considered solely to be taste receptors, but rather chemoreceptors used by several chemosensory modalities.…”

Espins Are Multifunctional Actin Cytoskeletal Regulatory Proteins in the Microvilli of Chemosensory and Mechanosensory Cells

“…Whether they were located in the VNO or in the nasal cavity, these espin-positive cells were stained by antibodies to ␣-gustducin ( Fig. 3A-C) and therefore likely coincided with the ␣-gustducin-positive cells noted previously in these locations (Zancanaro et al, 1999;Finger et al, 2003). These cells, which have been termed solitary chemoreceptor cells (SCCs), contain other components of a "bitter taste" transduction pathway and, in the nasal cavity, may trigger protective reflexes, such as apnea or sneezing, in response to irritants (Finger et al, 2003).…”