The role of tight junctions and aquaporins in skin dryness

Abstract

The maintenance of optimum water content in the skin and especially in the epidermis is provided by many orchestrated mechanisms. Water uptake into the dermis/epidermis, paracellular and transcellular water transport through the epidermis and water retention as well as controlled water loss in the stratum corneum have to be coordinated. Unbalance of these mechanisms results in dry skin. Following its paracellular route, water has to pass tight junctions before it can get into contact with the stratum corneum. For the transcellular route water channels, formed by so-called aquaporins, are of importance. Here, I will summarize our current knowledge of the involvement of aquaporin-formed pores and tight junctions in epidermal water homeostasis - as well as in other functions - and their putative roles in skin dryness.