Marjeta Lisjak (Author), Maja Potokar (Author), Robert Zorec (Author), Jernej Jorgačevski (Author)

Abstract

Water channel aquaporin 4 (AQP4) plays a key role in the regulation of water homeostasis in the central nervous system (CNS). It is predominantly expressed in astrocytes lining blood-brain and blood-liquor boundaries. AQP4a (M1), AQP4c (M23), and AQP4e, present in the plasma membrane, participate in the cell volume regulation of astrocytes. The function of their splicing variants, AQP4b and AQP4d, predicted to be present in the cytoplasm, is unknown.We examined the cellular distribution of AQP4b and AQP4d in primary rat astrocytes and their role in cell volume regulation. The AQP4b and AQP4d isoforms exhibited extensive cytoplasmic localization in early and late endosomes/lysosomes and in the Golgi apparatus. Neither isoform localized to orthogonal arrays of particles (OAPs) in the plasma membrane. The overexpression of AQP4b and AQP4d isoforms in isoosmotic conditions reduced the density of OAPs; in hypoosmotic conditions, they remained absent from OAPs. In hypoosmotic conditions, the AQP4d isoform was significantly redistributed to early endosomes, which correlated with the increased trafficking of AQP4-laden vesicles. The overexpression of AQP4d facilitated the kinetics of cell swelling, without affecting the regulatory volume decrease. Therefore, although they reside in the cytoplasm, AQP4b and AQP4d isoforms may play an indirect role in astrocyte volume changes.

Keywords

aquaporin;endosome;astrocyte volume;

Data

Language: English
Year of publishing:
Typology: 1.01 - Original Scientific Article
Organization: UL MF - Faculty of Medicine
UDC: 616-092
COBISS: 34742745 Link will open in a new window
ISSN: 2073-4409
Views: 166
Downloads: 61
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Other data

Secondary language: Slovenian
Secondary keywords: akvaporin;endosom;prostornina astrocitov;
Type (COBISS): Article
Pages: str. 1-17
Volume: ǂVol. ǂ9
Issue: ǂiss. ǂ3
Chronology: 2020
DOI: 10.3390/cells9030735
ID: 13961675