title: A kainate receptor subunit promotes the recycling of the neuron-specific K+-Cl-co-transporter KCC2 in hippocampal neurons.
abstract: Synaptic inhibition depends on a transmembrane gradient of chloride, which is set by the neuron-specific K+-Cl-co-transporter KCC2. Reduced KCC2 levels in the neuronal membrane contribute to the generation of epilepsy, neuropathic pain, and autism spectrum disorders; thus, it is important to characterize the mechanisms regulating KCC2 expression. In the present study, we determined the role of KCC2-protein interactions in regulating total and surface membrane KCC2 expression. Using quantitative immunofluorescence in cultured mouse hippocampal neurons, we discovered that the kainate receptor subunit GluK2 and the auxiliary subunit Neto2 significantly increase the total KCC2 abundance in neurons but that GluK2 exclusively increases the abundance of KCC2 in the surface membrane. Using a live cell imaging assay, we further determined that KCC2 recycling primarily occurs within 1-2 h and that GluK2 produces an ∼40% increase in the amount of KCC2 recycled to the membrane during this time period. This GluK2-mediated increase in surface recycling translated to a significant increase in KCC2 expression in the surface membrane. Moreover, we found that KCC2 recycling is enhanced by protein kinase C-mediated phosphorylation of the GluK2 C-terminal residues Ser-846 and Ser-868. Lastly, using gramicidin-perforated patch clamp recordings, we found that the GluK2-mediated increase in KCC2 recycling to the surface membrane translates to a hyperpolarization of the reversal potential for GABA (EGABA). In conclusion, our results have revealed a mechanism by which kainate receptors regulate KCC2 expression in the hippocampus.
authors.affiliation: From the Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada and.
authors.forename: Jessica C
authors.initials: JC
authors.lastname: Pressey
authors.affiliation: From the Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada and.
authors.forename: Vivek
authors.initials: V
authors.lastname: Mahadevan
authors.affiliation: From the Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada and.
authors.forename: C Sahara
authors.initials: CS
authors.lastname: Khademullah
authors.affiliation: From the Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada and.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Dargaei
authors.affiliation: From the Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada and.
authors.forename: Jonah
authors.initials: J
authors.lastname: Chevrier
authors.affiliation: From the Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada and.
authors.forename: Wenqing
authors.initials: W
authors.lastname: Ye
authors.affiliation: From the Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada and.
authors.forename: Michelle
authors.initials: M
authors.lastname: Huang
authors.affiliation: From the Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada and.
authors.forename: Alamjeet K
authors.initials: AK
authors.lastname: Chauhan
authors.affiliation: From the Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada and.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Meas
authors.affiliation: the Department of Anatomy, University of Helsinki, 00014 Helsinki, Finland.
authors.forename: Pavel
authors.initials: P
authors.lastname: Uvarov
authors.affiliation: the Department of Anatomy, University of Helsinki, 00014 Helsinki, Finland.
authors.forename: Matti S
authors.identifier: 0000-0002-7199-4984
authors.initials: MS
authors.lastname: Airaksinen
authors.affiliation: From the Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada and m.woodin@utoronto.ca.
authors.forename: Melanie A
authors.identifier: 0000-0003-2984-8630
authors.initials: MA
authors.lastname: Woodin
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism*; D008564:Membrane Potentials / Q000502:physiology*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D018092:Kainic Acid Receptors / Q000235:genetics / Q000378:metabolism*; D027981:Symporters / Q000235:genetics / Q000378:metabolism*; D000096922:K Cl- Cotransporters; D000097806:GluK2 Kainate Receptor
chemical_list: D008565:Membrane Proteins; D018092:Kainic Acid Receptors; D027981:Symporters; D000096922:K Cl- Cotransporters; D000097806:GluK2 Kainate Receptor; C539204:NETO2 protein, mouse
keywords: K+-Cl− co-transporter (KCC2); cation-chloride co-transporter (CCC); gamma-aminobutyric acid (GABA); glutamate receptor; membrane recycling; neuron; protein kinase C (PKC); protein phosphorylation