Hyperpolarizing GABAergic transmission requires the KCC2 C-terminal ISO domain.
J Neurosci
; 32(25): 8746-51, 2012 Jun 20.
Article
en En
| MEDLINE
| ID: mdl-22723714
ABSTRACT
KCC2 is the neuron-specific member of the of K(+)-Cl(-) cotransporter gene family. It is also the only member of its family that is active under physiologically normal conditions, in the absence of osmotic stress. By extruding Cl(-) from the neuron under isotonic conditions, this transporter maintains a low concentration of neuronal Cl(-), which is essential for fast inhibitory synaptic transmission by GABA and glycine in the mature nervous system. The other members of this K(+)-Cl(-) cotransporter gene family are exclusively swelling-activated. Here we demonstrate that a 15 aa region near the end of the C terminus, unique to KCC2 (termed the ISO domain), is required for KCC2 to cotransport K(+) and Cl(-) out of the neuron under isotonic conditions. We made this discovery by overexpressing chimeric KCC2-KCC4 cDNA constructs in cultured hippocampal neurons prepared from Sprague Dawley rat embryos and assaying neuronal Cl(-) through gramicidin perforated patch-clamp recordings. We found that when neurons had been transfected with a chimeric KCC2 that lacked the unique ISO domain, hyperpolarizing responses to GABA were abolished. This finding indicates that the ISO domain is required for neuronal Cl(-) regulation. Furthermore, we discovered that when KCC2 lacks the ISO domain, it still retains swelling-activated transport, which demonstrates that there are exclusive molecular determinants of isotonic and swelling-induced K(+)-Cl(-) cotransport in neurons.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Transmisión Sináptica
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Simportadores
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Ácido gamma-Aminobutírico
Límite:
Animals
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Pregnancy
Idioma:
En
Revista:
J Neurosci
Año:
2012
Tipo del documento:
Article