Aquaporins differentially regulate cell-cell adhesion in MDCK cells

Plasticity of epithelial cell-cell adhesion is vital in epithelial homeostasis and is regulated in multiple processes associated with cell migration, such as embryogenesis and wound healing. In cancer, cell-cell adhesion is compromised and is associated with increased cell migration and metastasis. Aquaporin (AQP) water channels facilitate water transport across cell membranes and are essential in the regulation of body water homeostasis. Increased expression of several AQPs, especially AQP5, is associated with increased cancer cell migration, metastasis, and poor prognosis. We found that AQP5 overexpression in normal epithelial cells induced cell detachment and dissemination from migrating cell sheets. AQP5 reduced both cell-cell coordination during collective migration and overall distance covered by the migrating cell sheets. AQP5 and the isoforms AQP1 and AQP4 decreased, whereas AQP3 increased, levels of plasma membrane-associated lateral junctional proteins. This regulation was mediated by the cytoplasmic domains of the AQPs. This shows that the AQPs have dual functions in epithelial physiology: as channel proteins and as differential regulators of cell-cell adhesiveness. This regulation may contribute to dynamic regulation of cell junctions in processes such as embryogenesis and wound healing and also explain the pivotal roles of AQPs in carcinogenesis and metastasis.-Login, F. H., Jensen, H. H., Pedersen, G. A., Koffman, J. S., Kwon, T.-H., Parsons, M., Nejsum, L. N. Aquaporins differentially regulate cell-cell adhesion in MDCK cells.