RT Book, Section A1 Baumann, Leslie SR Print(0) ID 1174541949 T1 Aquaporin T2 Cosmeceuticals and Cosmetic Ingredients YR 2015 FD 2015 PB McGraw-Hill Education PP New York, NY SN 9780071793988 LK dermatology.mhmedical.com/content.aspx?aid=1174541949 RD 2024/03/29 AB Aquaporins (AQPs) are integral membrane proteins that form a water channel and facilitate water transport in various organs such as the skin, renal tubules, eyes, the digestive tract, and the brain. In 2003, Peter Agre received the Nobel Prize in chemistry for discovering AQPs. There are 13 isoforms of AQPs found in mammals classified as types 1 to 13. Functionally, they can be classified into two subtypes: AQPs 1, 2, 4, 5, and 8, which only transport water, and AQPs 3, 7, 9, and 10, which can conduct other substances such as glycerol (also known as glycerin) or urea in addition to water.1 AQP-3 is the predominant water channel found in human epidermis, and is permeable to both water and glycerin. For years scientists have known that glycerin plays a superior role in hydrating skin,2 but the reasons for this became more clear when AQP-3 was discovered. Studies have shown that defects in AQP-3 in mice models result in epidermal dryness as well as decreased stratum corneum hydration and glycerin content of the epidermis, followed by reduced elasticity and impaired skin barrier recovery.3,4 Aquaporin facilitates the transport of water, glycerin, and solutes between keratinocytes.