Epithelial Tight Junction Proteins (TJ proteins)

Epithelial tight junction proteins are specialized intercellular structures that form a selective barrier between epithelial cells, regulating the paracellular movement of ions, water, and macromolecules (Anderson & Van Itallie, 2009). These proteins, including claudins, occludin, and zonula occludens (ZO) proteins, are essential for maintaining tissue compartmentalization and cell polarity (Zihni et al., 2016). In various diseases such as celiac disease and inflammatory bowel disease, the integrity of these junctions is compromised, leading to increased intestinal permeability and systemic inflammation (Fasano, 2011). Therapeutically, these proteins are targeted to either restore barrier function or transiently increase permeability for enhanced drug delivery. For example, larazotide acetate acts as a zonulin antagonist to prevent the breakdown of tight junctions in the gut (Khaleghi et al., 2021). Understanding the complex regulation of these proteins is crucial for developing treatments that address barrier dysfunction across multiple organ systems.

Other names

Zonula occludensOccluding junctionsIntercellular junctional complexesTight junctions

Drugs targeting epithelial tight junction proteins typically work by modulating the assembly or disassembly of the junctional complex. For instance, zonulin antagonists like larazotide acetate prevent the reorganization of the actin cytoskeleton and the subsequent opening of tight junctions (Khaleghi et al., 2021). Other agents, such as certain absorption enhancers, transiently disrupt these proteins to facilitate the paracellular transport of large molecules (McCartney et al., 2016).