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Taste receptor cells (TRCs) are the sensory cells of taste transduction and are organized into taste buds embedded in the epithelium of the tongue, palate, pharynx, and larynx. Several studies have demonstrated that TRCs involved in sweet as well as bitter and umami responses express α-gustducin, an α-subunit of the G-protein complex. It has been further demonstrated that this typical taste protein is a potent marker of chemosensory cells located in several tissues, including gastric and pancreatic mucosa and the respiratory apparatus. We recently observed that α-gustducin and phospholipase C beta 2–immunoreactive cells were colocalized in the airways with cystic fibrosis transmembrane regulator (CFTR) and Clara cell–specific secretory protein of 10 (CC10) and 26 kDa (CC26). This finding suggests that TRCs might themselves express secretory markers. To test this hypothesis, we investigated the expression of CFTR, CC10, and CC26 in rat circumvallate papillae using reverse transcriptase–polymerase chain reaction analysis, immunohistochemistry, and confocal laser microscopy. The results showed that secretory markers such as CFTR, CC10, and CC26 are present in taste cells of rat circumvallate papillae, and their immunoreactivity is expressed, to a different extent, in subsets of taste cells that express α-gustducin. The presence of CFTR, CC10, and CC26 in taste bud cells and their coexpression pattern with α-gustducin confirms and extends our previous findings in airway epithelium, lending further credence to the notion that chemoreception and secretion may be related processes. [ABSTRACT FROM AUTHOR]

The expression of molecules involved in the transductory cascade of the sense of taste (TRs, α-gustducin, PLCβ2, IP3R3) has been described in lingual taste buds or in solitary chemoreceptor cells located in different organs. At the laryngeal inlet, immunocytochemical staining at the light and electron microscope levels revealed that α-gustducin and PLCβ2 are mainly localized in chemosensory clusters (CCs), which are multicellular organizations differing from taste buds, being generally composed of two or three chemoreceptor cells. Compared with lingual taste buds, CCs are lower in height and smaller in diameter. In laryngeal CCs, immunocytochemistry using the two antibodies identified a similar cell type which appears rather unlike the α-gustducin-immunoreactive (IR) and PLCβ2-IR cells visible in lingual taste buds. The laryngeal IR cells are shorter than the lingual ones, with poorly developed basal processes and their apical process is shorter and thicker. Some cells show a flask-like shape due to the presence of a large body and the absence of basal processes. CCs lack pores and their delimitation from the surrounding epithelium is poorly evident. The demonstration of the existence of CCs strengthens the hypothesis of a phylogenetic link between gustatory and solitary chemosensory cells. [ABSTRACT FROM AUTHOR]

Objective: The antiapoptotic effect of p21Waf1/Cip1/Sdi1 (p21) was examined in human umbilical vein endothelial cells (HUVEC) exposed to laminar shear stress (SS) or to the nitric oxide donor sodium nitroprusside (SNP) and in a mouse model of hindlimb ischemia. Methods: In vitro: Cells were cultured without serum and in the presence of cobalt chloride to simulate hypoxia for 12 h (T0). Shear stress was applied to endothelial cells for additional 12 h. In vivo: Hindlimb ischemia was realized in mice by femoral artery ligation. SNP was acutely administered by subcutaneous injection or by Alzet osmotic pumps for a longer treatment. Results: At T0, HUVEC were either exposed to SS (15 dyn/cm2/s−1), treated with SNP or kept in static condition (ST) for 1–12 h; after additional 12 h in ST, 30–35% of cells still alive at T0 had died. In this condition, both SS and SNP treatments markedly increased p21 levels and reduced apoptosis in HUVEC. Recombinant adenoviruses carrying p21 (AdCMV.p21) or antisense p21 (AdCMV.ASp21) cDNA revealed that AdCMV.p21-infected HUVEC were protected from death while AdCMV.ASp21 reduced SS- and SNP-dependent protection from apoptosis. In mice, apoptosis was detected in endothelial cells of ischemic hindlimbs as early as 8 h after femoral artery ligation. Treatment with SNP enhanced p21 expression and protected ischemic tissue from damage. Remarkably, direct in vivo injection of AdCMV.p21 significantly reduced the number of apoptotic nuclei in the presence of ischemia. Conclusions: The present study establishes that, under our experimental conditions, (a) p21 plays an important role in SS and nitric oxide antiapoptotic effect in vitro, and (b) p21 gene transfer prevents apoptosis in vitro and in vivo, following acute interruption of blood flow. [Copyright &y& Elsevier]

The presence of solitary chemosensory cells was studied in rat vallate papillae during the first week of post-natal life by α-gustducin immunocytochemistry. In 1- to 3-day-old rats, isolated α-gustducin-immunoreactive cells were found within the epithelium of the vallate papilla. These cells, mainly located in the basal layer, were scattered among keratocytes and wrapped in α-gustducin-negative epithelial cells in a glia-like fashion. The α-gustducin-immunoreactive cells were usually round and some of them gave rise to short, large processes directed towards the lumen of the oral cavity or the basal lamina. Rarely, some cells showed an evident bipolar shape. Small taste buds containing either α-gustducin-immunoreactive or α-gustducinnegative cells appeared in the vallate papillae of 4-day-old rats in which isolated, bipolar-shaped α-gustducin-immunoreactive cells were also found. After the first week of post-natal life, the taste buds appeared basically similar to those of adult animals. In conclusion, the present study demonstrates that the presence of epithelial cells with characteristics of solitary chemosensory cells precedes the development of the taste buds. [ABSTRACT FROM AUTHOR]