Localization of ion channels along the neuronal surface

Orateur : Rafael LUJAN (Universidad de Castilla-La Mancha Albacete, Spain)

Brain function is driven by highly orchestrated actions of neurotransmitter receptors and ion channels expressed in anatomically, neurochemically and functionally diverse neurons. The highly compartmentalized nature of neuronal membranes reflects functional subcellular specialization that is essential for normal neurotransmission and plasticity. Therefore, the identification of the subcellular components in which ion channels are operative, and their density at the different neuronal compartments, is essential to understand the molecular mechanisms underlying their involvement in brain function and dysfunction. Using immunoelectron microscopic techniques, we are clarifying ion channel localization patterns in relation to synaptic structures (structure–function relationship) at various connections. We have shown that ion channels are not evenly distributed on the neuronal surface but instead concentrated at specific compartments in a subunit-, cell type-, synaptic input- and subcellular compartment-dependent manner. Small conductance Ca2+-activated K+ (SK) channels are localised at synaptic sites in dendritic spines, where they interact with NMDA receptors, but also at extrasynaptic sites, where they only interact with Group I mGlu receptors. Our data provide new insights into intra-synapse-type and inter-synapse-type relationships in terms of number/density and arrangement of ion channels along the neuronal surface, providing structural basis of functional properties of synaptic connections including synaptic plasticity.

Télécharger dans mon agenda