The aquaporins (AQPs) are a family of small integral membrane proteins that facilitate the bidirectional transport of water across biological membranes in response to osmotic pressure gradients as well as enable the transmembrane diffusion of small neutral solutes (such as urea, glycerol, and hydrogen peroxide) and ions. AQPs are expressed throughout the human body. Here, we review their key roles in fluid homeostasis, glandular secretions, signal transduction and sensation, barrier function, immunity and inflammation, cell migration, and angiogenesis. Evidence from a wide variety of studies now supports a view of the functions of AQPs being much more complex than simply mediating the passive flow of water across biological membranes. The discovery and development of small-molecule AQP inhibitors for research use and therapeutic development will lead to new insights into the basic biology of and novel treatments for the wide range of AQP-associated disorders.
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Funding: This work was supported by the Australian Research Council (grant number 19ARC_DP190
101745 to A.J.Y.), the UK Biotechnology and Biological Sciences Research Council (grant number
BB/P025927/1 to R.M.B. and P.K.), the European Union’s Horizon 2020 Research and Innovation
Programme under Marie Sklodowska Curie, grant agreement No. 847,419 (MemTrain; a studentship
to L.U.), an Aston University 50th Anniversary Fellowship (to P.K.), and GOstralia! PhD scholarship
support (to K.W.).
- Aquaporin (AQP)
- Facilitated diffusion