MUC5AC

MUC5AC Full Name

mucin 5AC, oligomeric mucus/gel-forming

MUC5AC Introduction

MUC5AC, or mucin 5AC, is a large gel-forming mucin predominantly produced by goblet cells in the airway, stomach, and conjunctival epithelium. As a heavily glycosylated high–molecular weight protein, it plays a central role in forming the protective mucus barrier that shields epithelial surfaces from physical, chemical, and microbial insults. MUC5AC is secreted into the mucosal lumen, where it hydrates and expands to create a viscoelastic gel that traps pathogens and particulates. Its expression is tightly regulated by developmental programs, environmental exposures, and inflammatory signals, making it a dynamic component of mucosal defense.

Figure 1. Molecular and signaling impact of MUC5AC in various malignancies. (Sources: Krishn SR, et al.; 2018)

Functionally, MUC5AC contributes to innate immunity and epithelial homeostasis. Its glycan-rich structure provides binding sites for pathogens, facilitating their clearance by mucociliary transport. MUC5AC helps maintain epithelial hydration, lubrication, and protection against proteolytic damage, while also influencing microbial composition through selective interactions with commensal and pathogenic organisms. Regulation of MUC5AC is driven by pathways such as EGFR, IL-13/STAT6, and various innate immune receptors; disturbances in these signaling networks can result in mucus hypersecretion, altered mucus viscosity, or impaired mucociliary clearance. Experimental studies show that overproduction of MUC5AC can increase mucus plugging, whereas deficiency compromises mucosal barrier integrity and increases susceptibility to infection.

Clinically, dysregulation of MUC5AC is associated with a range of respiratory, gastrointestinal, and ocular diseases. In chronic airway diseases—including asthma, chronic obstructive pulmonary disease, and cystic fibrosis—MUC5AC overexpression contributes to airway obstruction, inflammation, and exacerbations, making it a key therapeutic focus in mucolytic and anti-inflammatory strategies. Elevated MUC5AC is also observed in gastric diseases such as Helicobacter pylori–associated gastritis and gastric cancer, where altered mucin expression patterns reflect changes in epithelial differentiation and tumor biology. Additionally, MUC5AC serves as a biomarker in several cancers, including pancreatic and colorectal cancer, due to its aberrant expression and secreted nature. These disease associations highlight MUC5AC's essential role in mucosal protection and its importance as both a diagnostic marker and a potential therapeutic target in inflammation and cancer.

Alternate Names for MUC5AC

MUC5AC; mucin 5AC; oligomeric mucus/gel-forming; TBM; leB; MUC5; mucin-5AC; gastric mucin; tracheobronchial mucin; major airway glycoprotein; lewis B blood group antigen; mucin-5 subtype AC; tracheobronchial; mucin 5AC; oligomeric mucus/gel-forming pseudogene; mucin 5; subtypes A and C; tracheobronchial/gastric; anti-Mucin 5AC

• Immunohistochemistry Antibodies for Pathology

• 1. Krishn SR, et al.; Ramifications of secreted mucin MUC5AC in malignant journey: a holistic view. Carcinogenesis. 2018, 39(5):633-651.