Khakipoor, S;
Giannaki, M;
Theparambil, SM;
Zecha, J;
Küster, B;
Heermann, S;
Deitmer, JW;
(2019)
Functional expression of electrogenic sodium bicarbonate cotransporter 1 (NBCe1) in mouse cortical astrocytes is dependent on S255-257 and regulated by mTOR.
Glia
, 67
(12)
pp. 2264-2278.
10.1002/glia.23682.
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Abstract
The electrogenic sodium bicarbonate cotransporter 1, NBCe1 (SLC4A4), is the major bicarbonate transporter expressed in astrocytes. It is highly sensitive for bicarbonate and the main regulator of intracellular, extracellular, and synaptic pH, thereby modulating neuronal excitability. However, despite these essential functions, the molecular mechanisms underlying NBCe1-mediated astrocytic response to extracellular pH changes are mostly unknown. Using primary mouse cortical astrocyte cultures, we investigated the effect of long-term extracellular metabolic alkalosis on regulation of NBCe1 and elucidated the underlying molecular mechanisms by immunoblotting, biotinylation of surface proteins, intracellular H+ recording using the H+ -sensitive dye 2',7'-bis-(carboxyethyl)-5-(and-6)-carboxyfluorescein, and phosphoproteomic analysis. The results showed significant downregulation of NBCe1 activity following metabolic alkalosis without influencing protein abundance or surface expression of NBCe1. During alkalosis, the rate of intracellular H+ changes upon challenging NBCe1 was decreased in wild-type astrocytes, but not in cortical astrocytes from NBCe1-deficient mice. Alkalosis-induced decrease of NBCe1 activity was rescued after activation of mTOR signaling. Moreover, mass spectrometry revealed constitutively phosphorylated S255-257 and mutational analysis uncovered these residues being crucial for NBCe1 transport activity. Our results demonstrate a novel mTOR-regulated mechanism by which NBCe1 functional expression is regulated. Such mechanism likely applies not only for NBCe1 in astrocytes, but in epithelial cells as well.
| Type: | Article |
|---|---|
| Title: | Functional expression of electrogenic sodium bicarbonate cotransporter 1 (NBCe1) in mouse cortical astrocytes is dependent on S255-257 and regulated by mTOR |
| Location: | United States |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1002/glia.23682 |
| Publisher version: | http://dx.doi.org/10.1002/glia.23682 |
| Language: | English |
| Additional information: | © 2019 The Authors. Glia published by Wiley Periodicals, Inc. This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made. |
| Keywords: | acid-base, alkalosis, bicarbonate, glial cells, pH, signaling, Alkalosis, Animals, Astrocytes, Cells, Cultured, Cerebral Cortex, Female, Gene Expression, HeLa Cells, Humans, Male, Mice, Mice, Inbred C57BL, Mice, Knockout, Phosphorylation, Sodium-Bicarbonate Symporters, TOR Serine-Threonine Kinases |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences > Neuro, Physiology and Pharmacology |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10114494 |
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