Endothelial cell membrane and tight junction (TJ)

Endothelial cell membranes and tight junctions (TJs) are the primary structural determinants of the vascular barrier, controlling the paracellular movement of fluids, ions, and cells (StatPearls, 2023). TJs, also known as zonula occludens, consist of a complex network of transmembrane proteins—including claudins, occludin, and junctional adhesion molecules (JAMs)—that physically seal the space between adjacent endothelial cells (NCBI, 2022). These proteins are linked to the actin cytoskeleton via intracellular scaffolding proteins like zonula occludens-1 (ZO-1), which are vital for maintaining junctional stability and mediating intracellular signaling (PubMed, 2021). This barrier system is most highly developed in the blood-brain barrier (BBB), where it protects the central nervous system from fluctuating systemic conditions and neurotoxic substances (Nature Reviews Neuroscience, 2020). Pathological disruption of these junctions occurs in conditions such as sepsis, acute respiratory distress syndrome (ARDS), and cancer, where increased permeability leads to edema and tissue damage (Journal of Clinical Investigation, 2021). Therapeutic targeting of TJs involves using agents like glucocorticoids to stabilize the barrier or osmotic agents like mannitol to temporarily increase permeability for drug delivery (Mayo Clinic, 2023).

Other names

Zonula occludensEndothelial barrierParacellular sealBlood-brain barrier junctions

Modulation of paracellular permeability through the reorganization, phosphorylation, or transcriptional regulation of junctional proteins such as Claudin-5, Occludin, and ZO-1.