Mucus secretion pathway

The **mucus secretion pathway** refers to the complex biological processes by which specialized epithelial cells—primarily goblet cells and submucosal glands—synthesize, package, hydrate, and secrete polymeric glycoproteins called mucins. These mucins form the viscoelastic gel known as mucus that lines respiratory, digestive, urogenital tracts and other organs exposed to the external environment. The process is tightly regulated at multiple levels: • **Synthesis:** Polymeric mucins such as MUC5AC (from goblet cells) and MUC5B (from submucosal glands) are produced continuously. • **Packaging & Exocytosis:** Mature granules containing dehydrated mucin are positioned for release via a core exocytic machinery involving SNARE proteins like VAMP8/SNAP23/Munc18b; regulatory proteins such as MARCKS/Rab/HSP70 coordinate this process in response to extracellular signals. • **Hydration:** Upon release into the airway lumen or other surfaces, rapid water influx—mediated by chloride channels like CFTR—and bicarbonate transport is essential for proper unfolding/hydration of the dense granule contents into functional mucus. • **Function:** The hydrated mucus forms a mobile barrier propelled by cilia (“mucociliary clearance”), trapping inhaled particles/pathogens for removal from airways. Dysregulation can result in diseases such as cystic fibrosis (defective CFTR leading to thickened/underhydrated mucus), chronic bronchitis/asthma/COPD (overproduction), or increased infection risk if too little is produced. While individual molecular components within this pathway may be considered drug targets—for example CFTR chloride channel—the “mucus secretion pathway” itself is not a single molecule/receptor but rather an integrated physiological process involving many molecular players[1][2]. In summary: "Mucus secretion pathways" describes coordinated cellular processes responsible for producing protective surface mucus but does not correspond to one discrete druggable target protein/receptor/enzyme.[1][2]

Other names

Mucin secretion pathwayAirway mucin exocytosisGoblet cell secretory pathwayMucociliary clearance mechanisms

Modulation of ion channels to alter mucus hydration and viscosity; Stimulation or inhibition of mucin exocytosis from goblet cells