Mucin gene structure and expression: protection vs. adhesion

Abstract

The cloning of mucin cDNAs brought about by the application of molecular biology and molecular analyses constitutes a major step in understanding mucin structure and function. Here two classes of mucins are described: epithelium-associated and endothelium/leukocyte-associated mucins, which have thus far been described separately in the literature. The epithelial mucins are generally believed to play a role in cytoprotection. The endothelial and leukocyte class of mucins are adhesion molecules involved in lymphocyte homing and lymphocyte activation or are part of the adhesion cascade that plays a role in the initiation of inflammation. Mucins in general contain many threonine and serine residues, which are extensively O-glycosylated. Due to this profound glycosylation, mucins have a filamentous conformation. By virtue of their extended filamentous, and often negatively charged, structure, mucins can act as a barrier protecting the cell. However, when an opposing cell has specific receptors for mucins, adhesion can override the barrier function. Therefore, mucins may be powerful two-edged swords: they are both protective and adhesive.

Intestinal trefoil factor binds to intestinal epithelial cells and induces nitric oxide production: priming and enhancing effects of mucin

“…Epithelial cell-associated mucin has an important protective role in the gastrointestinal tract [40]. In co-operation with mucin glycoproteins, ITF protects cultured intestinal epithelial cells against a variety of injurious agents [12,14].…”

Subcellular localization of ATBF1 regulates MUC5AC transcription in gastric cancer

“…1 In normal gastric epithelium, MUC5AC is highly expressed in foveolar cells of the body and the antrum, [2][3][4] while MUC6 is expressed in the pyloric glands of the antrum. 5,6 Other mucins are not generally expressed in normal gastric mucosa, although MUC2 is often focally expressed in some gastric epithelium.…”

The Surface Coat of the Mammal-dwelling Infective Trypomastigote Stage of Trypanosoma cruzi Is Formed by Highly Diverse Immunogenic Mucins

“…The major protein components of this coat have been identified as glycosylphosphatidylinositol (GPI) 1 -anchored molecules enriched in Thr, Ser, and Pro residues that serve as a scaffold for the extensive addition of O-glycans (5, 8 -10, 12). This particular feature enables their classification as mucin-like proteins by analogy to mammalian mucins (13). Mucins play a key role in parasite protection and infectivity and modulation of the host immune response throughout the T. cruzi life cycle (14 -16).…”