The apical membrane of intestinal brush cells possesses a specialised, but species-specific, composition of glycoconjugates – on-section and in vivo lectin labelling in rats, guinea-pigs and mice

Abstract

Brush cells are specialised epithelial cells that are assumed to represent chemoreceptors of the digestive tract. They comprise a small population of the epithelial cells lining the intestine, possess a unique ultrastructure and, in many aspects, resemble the receptor cells of taste buds. To characterise glycoconjugates possibly involved in a sensory function, we investigated brush cells in the small intestine of three species using lectin histochemistry in confocal light and thin-section electron microscopy. Brush cells of rats were selectively labelled by the sialic acid-specific lectin Maackia amurensis agglutinin, those of guinea-pigs by the D-galactose-specific lectin Bandeiraea simplicifolia agglutinin, isolectin B 4 and those of mice by the L-fucose-specific lectin Ulex europaeus agglutinin lectin I. Lectin binding sites were consistently located in the glycocalyx of the apical membrane and in that of cytoplasmic vesicles. In vivo lectin labelling revealed that the glycoconjugates of the apical membrane are accessible under physiological conditions, that brush cells do not endocytose and that they probably possess a high membrane turnover rate. The results show that specialisations exist in the composition of glycoconjugates forming the glycocalyx of brush cells in all species investigated. The presence of brush cell-specific glycoconjugates would be in accordance with the current hypothesis of a receptive function of brush cells. Differences in the specific glycosylation patterns among rats, guinea-pigs and mice indicate that species-specific adaptations exist.

Isolation and partial characterization of gypsy moth BTR‐270, an anionic brush border membrane glycoconjugate that binds Bacillus thuringiensis Cry1A toxins with high affinity

“…Phenol-water extraction, originally used to extract lipopolysaccharides, has been applied for the preparation of mucins (Gold et al, 1981), and glycocalyces (Caulfield et al, 1987). The glycocalyx of intestinal brush cells is a carbohydrate-rich material with a polyanionic nature that is composed of glycoconjugates that differ in glycosylation patterns in all species examined (Gebet et al, 2000). At present there is no comprehensive analysis of the protein components of the intestinal epithelial glycocalyx.…”

Brush cells in the human duodenojejunal junction: an ultrastructural study

“…1987; Sato & Miyoshi, 1997). Gebert et al. (2000) reported that some BCs examined by electron microscopy showed an inhomogeneous distribution of lectin‐bound glycoconjugates.…”

Comparative histochemical analysis of intestinal glycoconjugates in the blunthead pufferfish Sphoeroides pachygaster and grey triggerfish Balistes capriscus (Teleostei: Tetraodontiformes)

“…The enterocyte brush border glycocalyx was more evident in B. capriscus than in S. pachygaster . This glycocalyx is known to mediate many functions such as the absorption of nutrients, microbial adhesion, antigen uptake and chemoreception and its alteration under pathologic conditions has been studied previously (Gebert et al ., ; Kavanaugh et al ., ; Løkka & Koppang, ). The meaning of such a developed glycocalyx is not clear (even with a lower number of residuals than other species, as noted previously), although it probably implies a greater need to regulate these processes in B. capriscus .…”