Mucinology

Mucinology is the branch of biochemistry and physiology that studies mucins, a family of high molecular weight, heavily glycosylated glycoproteins produced by epithelial tissues. Mucins are the major component of mucus and contribute to lubrication, protection, and selective permeability of mucosal surfaces. They can be secreted to form gels (secreted mucins) or attached to the cell surface as membrane-associated mucins, where they participate in signaling and cell adhesion.

Secreted gel-forming mucins include MUC2, MUC5AC, MUC5B, and MUC6, while transmembrane mucins include MUC1, MUC4, MUC16, and MUC17. Mucin genes encode large proteins with extensive variable number tandem repeat regions rich in serine and threonine, the primary sites of O-linked glycosylation. The resulting glycan chains confer hydration and steric properties that influence viscosity and barrier function.

Physiological roles span protection against pathogens, lubrication of mucosal surfaces, hydration regulation, and influences on microbial communities. Membrane mucins also participate in signal transduction, receptor clustering, and cell–cell interactions.

Distribution varies by tissue: gastrointestinal, respiratory, reproductive, and ocular epithelia each express distinct mucin repertoires. Alterations in mucin expression or glycosylation are linked to diseases such as cystic fibrosis, inflammatory bowel disease, gastric or pancreatic cancer, and asthma, making mucins useful biomarkers and potential therapeutic targets.

Research approaches include biochemical purification of mucins, glycoproteomics, gene expression profiling, immunohistochemistry, and histochemical staining (for example, periodic acid–Schiff and Alcian blue) to detect carbohydrate components.