BECLIN-1/BECN1 at the barrier: a gatekeeper of epithelial and endothelial homeostasis

Epithelial and endothelial barriers are essential for tissue homeostasis, protecting the body from environmental insults while regulating selective transport. The integrity of these barriers relies on dynamic intercellular junctions whose composition and organization are constantly remodeled in response to stress and physiological cues. Autophagy and endocytic trafficking are key intracellular pathways that maintain junctional stability and barrier resilience. BECLIN-1 (BECN1), a central regulator of both pathways, coordinates localized membrane dynamics through its interaction with the class III phosphatidylinositol 3-kinase (PtdIns3K) PIK3C3/VPS34. Recent advances reveal that BECN1's dual role in autophagy and endocytic trafficking is crucial for maintaining barriers in diverse tissues, including the gut, skin, and blood-brain barrier. Conversely, BECN1 dysfunction can compromise junctional integrity, driving inflammatory and degenerative diseases. This review summarizes the emerging evidence linking BECN1 to membrane trafficking, stress adaptation, and immune regulation across barrier tissues, highlighting its potential as a therapeutic target for barrier-associated diseases.