Mucin 5AC protein (MUC5AC)

Mucin 5AC protein (MUC5AC) is a high-molecular-weight, gel-forming, O-glycosylated secreted mucin produced predominantly by goblet cells lining the respiratory tract and surface gastric epithelium[2][3][8][9]. MUC5AC is a key component of airway and gastric mucus, which forms a protective barrier, maintains hydration, and traps pathogens. Structural and biochemical studies demonstrate that MUC5AC assembles into large, disulfide-bonded polymers contributing to the viscoelastic properties of mucus[1][2][4][5]. Its expression increases dramatically in response to airway injury, inflammation, and specific cytokine signaling. Overproduction or altered structure of MUC5AC is implicated in chronic inflammatory airway diseases (such as asthma, COPD), mucous cell metaplasia, infection-related mucus plugging, and cancer. Despite being a promising therapeutic target for mucus overproduction disorders, direct pharmacological inhibitors are still under investigation due to the protein's importance in epithelial protection and innate immunity[3][6][7][9].

Other names

MUC5ACMucin-5ACMucin 5, subtypes A and CGel-forming mucin 5AC

Transcriptional suppression (e.g., by glucocorticoids/activation of glucocorticoid receptor)[6][7] Transcriptional regulation by NF-κB and Sp1 pathways affecting mucin gene expression[6][7] Epigenetic modulation (e.g., via coactivator P300)[6][7]