タイト結合の形態と機能
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概要
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Tight junctions (TJs) constitute the epithelial apical junctional complex together with adherens junctions and desmosomes at the most apical region of the lateral plasma membranes. TJs function as a barrier to regulate the paracellular permeability and as a fence to prevent intermixing plasma membrane proteins between the apical and baso-lateral plasma membrane domains. Claudins are integral membrane proteins at TJs, consist of at least 24 members in humans and mice and reconstitute TJs in TJ-free fibroblasts. As claudins show a tissue-specific distribution pattern, the tissue-specific morphological features and physiological properties of TJs may be determined by the combination and mixing ratio of claudin species in the tissue. Claudins are believed to assemble into multimers by homophilic and heterophilic side-by-side in one membrane (cis-interaction) and head-to-head interaction between adjacent cells (trans-interaction) to form TJs. However, there are several examples of incompatible trans-interactions between claudin species, including claudin-1 versus claudin-15. Exogenous expression of claudin-15 induced aberrant TJs in lateral membranes in MDCK II cells expressing claudin-1, and some tumor cells formed aberrant TJs. From these results, the incompatibility may affect the structure and function of TJs. In this review, we introduce recent progresses in TJ research, including our results, especially focusing on how claudins regulate the structure and function of TJs.
- 2010-09-30