Author/Editor     Lisjak, Marjeta; Potokar, Maja; Rituper, Boštjan; Jorgačevski, Jernej; Zorec, Robert
Title     AQP4e-based orthogonal arrays regulate rapid cell volume changes in astrocytes
Type     članek
Publication year     2017
Volume     str. str.
ISSN     0270-6474 - The Journal of neuroscience : the official journal of the Society for Neuroscience
Language     eng
Abstract     Water channel aquaporin 4 (AQP4) plays a key role in the regulation of water homeostasis in the brain. It is predominantly expressed in astrocytes at blood-brain and blood-liquor interfaces. Although several AQP4 isoforms have been identified in the mammalian brain, two, AQP4a (M1) and AQP4c (M23), have been confirmed to cluster into plasma membrane supramolecular structures, termed orthogonal arrays of particles (OAPs) and to enhance water transport through the plasma membrane. However, the role of the newly described water-conductive mammalian isoform AQP4e is unknown. Here, the dynamics of AQP4e aggregation into OAPs and its role in the regulation of astrocyte water homeostasis have been studied. Using super-resolution structured illumination, atomic force, and confocal microscopies, the results revealed that, in female rat astrocytes, AQP4e isoform co-localizes with OAPs, affecting its structural dynamics. In hypoosmotic conditions, which elicit cell edema, OAP formation was considerably enhanced by overexpressed AQP4e. Moreover, the kinetics of the cell swelling and of the regulatory volume decrease (RVD) was faster in astrocytes overexpressing AQP4e, compared with untransfected controls. Furthermore, the increase in maximal cell volume elicited by hypoosmotic stimulation was significantly smaller in AQP4e overexpressing astrocytes. For the first time, this study demonstrates an active role of AQP4e in the regulation of OAP structural dynamics and in water homeostasis.
Keywords     orthogonal arrays
astrocytes
cell volume changes
ortogonalni nizi
astrociti
sprememba volumna celic