Activity-dependent regulation of the K/Cl transporter KCC2 membrane diffusion, clustering, and function in hippocampal neurons
Journal of Neuroscience. 2013-09-25; 33(39): 15488-15503
DOI: 10.1523/JNEUROSCI.5889-12.2013
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1. J Neurosci. 2013 Sep 25;33(39):15488-503. doi: 10.1523/JNEUROSCI.5889-12.2013.
Activity-dependent regulation of the K/Cl transporter KCC2 membrane diffusion,
clustering, and function in hippocampal neurons.
Chamma I(1), Heubl M, Chevy Q, Renner M, Moutkine I, Eugène E, Poncer JC, Lévi S.
Author information:
(1)Institut National de la Santé et de la Recherche Médicale (INSERM), Unité
Mixte de Recherche en Santé 839, F-75005 Paris, France, Université Pierre et
Marie Curie, F-75005 Paris, France, Institut du Fer a Moulin, F-75005 Paris,
France, and Institut de Biologie de l’Ecole Normale Supérieure, INSERM, Unité
1024, Centre National de la Recherche Scientifique, Unité Mixte de Recherche
8197, F-75005 Paris, France.
The neuronal K/Cl transporter KCC2 exports chloride ions and thereby influences
the efficacy and polarity of GABA signaling in the brain. KCC2 is also critical
for dendritic spine morphogenesis and the maintenance of glutamatergic
transmission in cortical neurons. Because KCC2 plays a pivotal role in the
function of central synapses, it is of particular importance to understand the
cellular and molecular mechanisms underlying its regulation. Here, we studied the
impact of membrane diffusion and clustering on KCC2 function. KCC2 forms clusters
in the vicinity of both excitatory and inhibitory synapses. Using
quantum-dot-based single-particle tracking on rat primary hippocampal neurons, we
show that KCC2 is slowed down and confined at excitatory and inhibitory synapses
compared with extrasynaptic regions. However, KCC2 escapes inhibitory synapses
faster than excitatory synapses, reflecting stronger molecular constraints at the
latter. Interfering with KCC2-actin interactions or inhibiting F-actin
polymerization releases diffusion constraints on KCC2 at excitatory but not
inhibitory synapses. Thus, F-actin constrains KCC2 diffusion at excitatory
synapses, whereas KCC2 is confined at inhibitory synapses by a distinct
mechanism. Finally, increased neuronal activity rapidly increases the diffusion
coefficient and decreases the dwell time of KCC2 at excitatory synapses. This
effect involves NMDAR activation, Ca(2+) influx, KCC2 S940 dephosphorylation and
calpain protease cleavage of KCC2 and is accompanied by reduced KCC2 clustering
and ion transport function. Thus, activity-dependent regulation of KCC2 lateral
diffusion and clustering allows for a rapid regulation of chloride homeostasis in
neurons.
DOI: 10.1523/JNEUROSCI.5889-12.2013
PMID: 24068817 [Indexed for MEDLINE]