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Gut. 1999 Mar;44(3):387-93.

Sulphation and secretion of the predominant secretory human colonic mucin MUC2 in ulcerative colitis.

Author information

  • 1Pediatric Gastroenterology and Nutrition, Department of Pediatrics, University of Amsterdam, Academic Medical Centre, Amsterdam, The Netherlands.

Abstract

BACKGROUND:

Decreased synthesis of the predominant secretory human colonic mucin (MUC2) occurs during active ulcerative colitis.

AIMS:

To study possible alterations in mucin sulphation and mucin secretion, which could be the cause of decreased mucosal protection in ulcerative colitis.

METHODS:

Colonic biopsy specimens from patients with active ulcerative colitis, ulcerative colitis in remission, and controls were metabolically labelled with [35S]-amino acids or [35S]-sulphate, chase incubated and analysed by SDS-PAGE, followed by quantitation of mature [35S]-labelled MUC2. For quantitation of total MUC2, which includes non-radiolabelled and radiolabelled MUC2, dot blotting was performed, using a MUC2 monoclonal antibody.

RESULTS:

Between patient groups, no significant differences were found in [35S]-sulphate content of secreted MUC2 or in the secreted percentage of either [35S]-amino acid labelled MUC2 or total MUC2. During active ulcerative colitis, secretion of [35S]-sulphate labelled MUC2 was significantly increased twofold, whereas [35S]-sulphate incorporation into MUC2 was significantly reduced to half.

CONCLUSIONS:

During active ulcerative colitis, less MUC2 is secreted, because MUC2 synthesis is decreased while the secreted percentage of MUC2 is unaltered. Furthermore, sulphate content of secreted MUC2 is unaltered by a specific compensatory mechanism, because sulphated MUC2 is preferentially secreted while sulphate incorporation into MUC2 is reduced.

PMID:
10026326
PMCID:
PMC1727426
[PubMed - indexed for MEDLINE]
Free PMC Article
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