Gastrointestinal mucin (MUC)

Gastrointestinal mucins are high-molecular-weight, heavily O-glycosylated proteins that serve as the primary structural component of the mucus layer protecting the digestive tract. These glycoproteins are secreted by specialized cells, such as goblet cells in the intestines and mucous neck cells in the stomach, to form a viscoelastic gel that acts as a physical and chemical barrier against acid, digestive enzymes, and enteric pathogens (Corfield, 2015, PMID: 25907171). In the stomach, mucins such as MUC5AC and MUC6 create a pH gradient that shields the underlying epithelium from the corrosive effects of gastric acid and pepsin. In the intestines, MUC2 is the predominant gel-forming mucin, creating a dense inner layer that remains largely sterile and a loose outer layer that houses the commensal microbiota (Hansson, 2012, PMID: 22343484). Dysfunction or depletion of the mucin barrier is a hallmark of several gastrointestinal diseases, including ulcerative colitis and peptic ulcer disease (McGuckin et al., 2011, PMID: 21386865). Pharmacological targeting of these glycoproteins involves cytoprotective drugs like sucralfate, which binds to the glycoprotein-rich base of ulcers, or secretagogues like rebamipide that enhance the endogenous production of these protective molecules (Arakawa et al., 2005, PMID: 16155405).

Other names

Gastrointestinal mucosal glycoproteins and mucinsGastric mucinIntestinal mucinMucus glycoproteinsMUC proteins

Drugs targeting gastrointestinal mucins primarily act by either forming a protective physical complex with the existing glycoprotein matrix (cytoprotection), stimulating the synthesis and secretion of new mucins from goblet and mucous cells (secretagogues), or enzymatically/chemically reducing the viscosity of the mucus layer (mucolytics).