Tight junctions (TJ) are intercellular structures that control paracellular permeability (i.e., the diffusion of water and solutes across intercellular spaces). They consist of transmembrane proteins (e.g., claudins, occludin, and junctional adhesion molecules) and of plaque proteins (e.g., zonula occludens proteins ZO-1, ZO-2, and ZO-3; Fig. 3).50 Studies in animal models have suggested the importance of TJ for control of skin permeability. Furuse et al. reported that mice lacking claudin-1 die because of significant body dehydration.” (Page 79, this document).
In other words, although we’ve long thought that the barrier to water loss was thanks to the intercellular lipids, like our natural moisturizing factors and stratum corneum lipids, it turns out that there’s another structure – the tight junction – that can help prevent moisture loss.
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