Ocular surface mucin glycoprotein (MUC) (MUC)

Ocular surface mucin glycoproteins are high-molecular-weight, heavily glycosylated proteins that are essential for maintaining the health and stability of the tear film (Gipson, 2004, PubMed: 14967200). They are categorized into membrane-associated mucins, such as MUC1, MUC4, and MUC16, which form the glycocalyx, and secreted mucins like MUC5AC, which provide lubrication (Mantelli & Argüeso, 2008, PubMed: 18614312). These proteins play a critical role in protecting the corneal and conjunctival epithelia from desiccation, mechanical friction, and pathogen invasion (TFOS DEWS II, 2017). In diseases like dry eye, mucin expression or glycosylation is often altered, leading to tear film instability and ocular surface damage. Therapeutic strategies focus on increasing mucin production or providing synthetic mimetics to restore the protective barrier. Drugs like rebamipide and diquafosol target these pathways to enhance the mucin layer and improve patient symptoms (DrugBank DB08814). Understanding the specific roles of different mucins helps in developing targeted therapies for various ocular surface disorders. The glycocalyx formed by these mucins also facilitates cell signaling and maintains the hydrophilic nature of the ocular surface.

Other names

MucinsOcular mucinsMembrane-associated mucinsSecreted mucinsGlycocalyx glycoproteinsMUC1MUC4MUC16MUC5AC

Mucin secretagogues (e.g., diquafosol) stimulate the release of mucins from conjunctival goblet cells, while mucin expression enhancers (e.g., rebamipide) upregulate the synthesis of membrane-associated mucins; mucin mimetics provide exogenous lubrication to stabilize the tear film (DrugBank DB08814, DB12646).