RESUMEN
KCC2 is the neuron-specific K+-Cl(-) cotransporter required for maintaining low intracellular Cl(-), which is essential for fast inhibitory synaptic transmission in the mature CNS. Despite the requirement of KCC2 for inhibitory synaptic transmission, understanding of the cellular mechanisms that regulate KCC2 expression and function is rudimentary. We examined KCC2 in its native protein complex in vivo to identify key KCC2-interacting partners that regulate KCC2 function. Using blue native-polyacrylamide gel electrophoresis (BN-PAGE), we determined that native KCC2 exists in a macromolecular complex with kainate-type glutamate receptors (KARs). We found that KAR subunits are required for KCC2 oligomerization and surface expression. In accordance with this finding, acute and chronic genetic deletion of KARs decreased KCC2 function and weakened synaptic inhibition in hippocampal neurons. Our results reveal KARs as regulators of KCC2, significantly advancing our growing understanding of the tight interplay between excitation and inhibition.
Asunto(s)
Cloruros/metabolismo , Hipocampo/metabolismo , Neuronas/metabolismo , Receptores de Ácido Kaínico/metabolismo , Simportadores/metabolismo , Animales , Femenino , Hipocampo/citología , Homeostasis , Masculino , Ratones Endogámicos C57BL , Neuronas/citología , Cotransportadores de K ClRESUMEN
KCC2 is a neuron-specific K(+)-Cl(-) cotransporter that is essential for Cl(-) homeostasis and fast inhibitory synaptic transmission in the mature CNS. Despite the critical role of KCC2 in neurons, the mechanisms regulating its function are not understood. Here, we show that KCC2 is critically regulated by the single-pass transmembrane protein neuropilin and tolloid like-2 (Neto2). Neto2 is required to maintain the normal abundance of KCC2 and specifically associates with the active oligomeric form of the transporter. Loss of the Neto2:KCC2 interaction reduced KCC2-mediated Cl(-) extrusion, resulting in decreased synaptic inhibition in hippocampal neurons.