Lectin-Gold Localization of Fucose Residues in Human Gastric Mucosa

Abstract

SUMMARYThe oligosaccharides of the mucous gastric glycoproteins are involved in the protection of the gastric mucosa and are altered in different diseases. Therefore, it is important to know their composition in health, to better determine the alterations induced by the disease. Moreover, analysis of the molecular composition of the fundic gland cells has been previously used to obtain new insights into the origin of the different cell types. The aim of the present study was the localization in the subcellular structures of the fucose residues of the oligosaccharides in human fundic glands. For this, lectin cytochemical methods were used at the light and electron microscopic levels. They were combined with enzymatic and chemical treatments to characterize the nature of the oligosaccharide chains containing the fucose residues. The presence of this carbohydrate belonging to N-or O-linked oligosaccharides has been demonstrated in the secretory granules of the surface, gastric pit, mucous neck, and transitional cells of the fundic mucosa, and in the intracellular canaliculi and tubulovesicular system of the parietal cells. These fucose residues were added in the trans-Golgi regions to the elongating chains. The term "mucosal defense" refers to the factors that permit the gastric mucosa to withstand frequent exposure to substances with a wide range of properties including, e.g., pH, osmolarity, and detergent properties. The first level of defense consists of the factors secreted into the lumen, including acid, bicarbonate, mucus, immunoglobulins, and other antibacterial substances (Wallace and Granger 1996). Mucous secretions form a barrier that traps bicarbonate secreted by the epithelium and stops acid retrodiffusion from the gastric lumen. Moreover, bacteria become trapped in the mucus and are eventually excreted in the feces (Wallace and Granger 1996).

Role for α- l -fucosidase in the control of Helicobacter pylori -infected gastric cancer cells

“…L-fucose is an abundant component of many host gastric mucosa glycoconjugates (35) that are constitutively synthesized by host cells. Thus, the ''request'' from H. pylori to manufacture fucosylated glycans may require the host to activate translation of 1 or more of its fucosyltransferase proteins.…”

Secretory granules of endocrine and chief cells of human stomach mucosa contain leptin

“…These granules had the ultrastructure of pepsinogen granules. 17,18 No differences were noted between the non-obese subjects and the obese patient.…”

Histochemical Demonstration of Two Subtypes of O‐linked Oligosaccharides in the Rat Gastric Glands

“…The increase in the lectin staining after O-linked oligosaccharides removal has been previously described in different tissues. This has been explained suggesting the presence of N-linked oligosaccharides, which were masked by the removed O-linked oligosaccharides (Alonso et al, 2003;Leis et al, 1997;Madrid et al, 1998aMadrid et al, ,b, 2000. However, this possibility can be ruled out because this staining is not abolished when PNGase-F is also used with the short b-elimination procedure.…”

“…The atomic force microscope has shown the pig gastric mucins as a filamentous strand (Deacon et al, 2000). They are highly glycosylated, mainly by O-linked oligosaccharides, although the presence of N-linked oligosaccharides in the mucous secretions of the gastrointestinal tract has also been demonstrated (Klomp et al, 1994;Madrid et al, 1998aMadrid et al, 2000Strous and Dekker, 1992).…”