Abstract
A plethora of neurological disorders are associated with alterations in the expression and localization of the potassium-chloride co-transporter type 2 (KCC2), making KCC2 a critical player in neuronal function and an attractive target for therapeutic treatment. The activity of KCC2 is determined primarily by the rates of its surface insertion and internalization. Currently the domains of KCC2 dictating its trafficking and endocytosis are unknown. Here, using live-cell immunolabelling and biotinylation of KCC2 proteins expressed either in murine neuroblastoma N2a cells, human embryonic kidney 293 cells or primary cultures of rat hippocampal neurons, we identified a novel role for the intracellular N- and C-termini in differentially regulating KCC2 surface expression. We report that the N-terminus is required for KCC2 insertion into the plasma membrane, while the C-terminus is critical for the membrane stability of KCC2. Our results provide novel insights into the structure-function role of specific KCC2 domains and open perspectives in exploring structural organization of this protein.
Significance Statement The neuronal potassium-chloride co-transporter KCC2 is critically involved in numerous neurologic disorders. However, the structural components that regulate KCC2 activity remain to be elucidated. Here, we describe novel and differential roles for the intracellular amino- and carboxy-terminal domains of KCC2 that dictate its plasmalemmal insertion and surface stabilization. Our findings challenge the current view on the structure-function role of the cytoplasmic regions of KCC2 and propose new targets in the search for therapeutic treatments.
Footnotes
The authors declare that they have no conflicts of interest.
This work was supported by the Institut National de la Santé et de la Recherche Médicale (INSERM) I.M and C.R, Aix-Marseille University (AMU) to I.M and C.R, University of Helsinki (C.R), the Agence Nationale de la Recherche (ANR) (TRAUMEP ANR 13-BSV4-0012-01 to C.R. and I.M), Academy of Finland (SA 259799 to CR). P.F. was supported by an INSERM-CR-PACA-FEDER grant and A.L. was supported by the Academy of Finland (SA 250742).
Guidelines of the Animal Care: All manipulations with animals were performed in agreement with the guidelines of the Animal Care and Use Committee of INSERM (Institut National de la Santé et de la Recherche Médicale).
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license, which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed.
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