Histochemical characterization of the sialic acid residues in mouse colon mucins

Abstract

The mucins of colonic murine mucus are highly O-glycosilated sulfosialoglycoproteins. We have characterized the sialylation pattern of oligosaccharide chains of colonic murine mucins by conventional histochemical methods and by lectin histochemistry combined with chemical pretreatments and sialidase digestion. Oligosaccharide chains are strongly sulphated, with an increase of sulfation from the proximal toward the distal colon and a decrease of sialic acid expression and acetylation toward the distal colon. In the goblet cells of proximal colon, sialic acid bound α2,3 to Galβ1,3GalNAc subterminal dimers is diacetylated at C7,C8;C7,C9;C8,C9 or triacetylated at C7,8,9. In the distal colon, sialic acid-linked α2,3 to Galβ1,3GalNAc subterminal dimers shows reduced O-acetylation at C7 and/or C8, while acetyl substituents at C9 and at C4 are almost absent. Sialic acid is involved in different essential physiological functions; thus, alterations of its expression and acetylation in oligosaccharide chains of intestinal mucins are generally associated with diseases, such as ulcerative colitis and cancer. Mice may represent a suitable animal model to study alterations of oligosaccharidic chains in colonic mucins and lectin histochemistry combined with chemical pretreatments, and enzyme digestion may be a valuable tool for this study. Our present work may represent a landmark for further lectin histochemical studies to evaluate alterations of mouse colon mucins under different physiological, pathological, or experimental conditions, with possible translational value in humans.

Comparative Analysis of the Morphology, Ultrastructure, and Glycosylation Pattern of the Jejunum and Ileum of the Wild Rodent Lagostomus maximus

“…In L. maximus , sialic acid was highly O‐acetylated and was particularly abundant in the jejunum, while ileal goblet cells showed a slight staining with the PA/Bh/KOH/PAS technique. Several authors have demonstrated that the degree of acetylation of sialomucins may influence the efficacy of the protective action against the mucus bacterial degradation because the substituent groups represent a steric effect (Mastrodonato et al, ). Therefore, assuming that the sialic acid acetylation enhances the resistance to bacterial breakdown of glycans (Mastrodonato et al, ), it can be hypothesized that the decrease in staining intensity of goblet cells with the PA/Bh/KOH/PAS technique in the ileum of the viscacha could reduce the resistance of these mucins against bacterial sialidase; nevertheless, the protective role in this intestinal region could probably be played by highly sulfated mucins.…”

“…Evaluation of labeling intensities was assessed by two independent observers and classified as: negative (0), weak (1), moderate (2), and strong (3). This classification was established according to previous reports (Liquori et al, ; Boonzaier et al, ; Mastrodonato et al, ).…”

“…Recent studies on mammals have shown that both the distribution of goblet cells and the mucin subtypes vary spatially as well as temporally all along the gastrointestinal tract, and according to specific factors such as animal species, age, position along crypt‐villus axis, diet, and bacterial status (Beyaz and Liman, ; Liquori et al, ; Mastrodonato et al, ; Tano de la Hoz et al, ).…”

Histochemistry of the zona pellucida of the ovary of a species with natural polyovulation: Lagostomus maximus (Rodentia, Hystricomorpha, Chinchillidae)

“…Of each ovary, no less than 15 follicles in which the ZP was evident were observed; among them: preantral, secondary, tertiary, polyovulatory and atretic follicles. The intensities of the different techniques were classified according to the following semi‐quantitative scale: 0, unlabelled; 1, light mark; 2, moderate mark; and 3, strong mark, according to the criterion used in previous works (Barbeito, Ortega, Matiller, Gimeno, & Salvetti, ; Boonzaier, Merwe, Bennett, & Kotze, ; Liquori et al, ; Mastrodonato, Mentino, Liquori, & Ferri, ; Plaul, Barbeito, & Díaz, ), including some carried out in the species under study (Flamini et al, ; Tano de la Hoz, Flamini, & Díaz, ).…”

Comparative glycopattern analysis of mucins in the Brunner's glands of the guinea-pig and the house mouse (Rodentia)

“…Details for the lectins employed, their concentrations, their sugar specificities and references are summarized in Table 1. Lectin protocols followed Mentino et al (2014) and Mastrodonato et al (2013). Sections were incubated for 1 h at room temperature with the lectin solution in HEPES and subsequently rinsed in the same buffer and mounted in Fluoromount (Sigma-Aldrich).…”