title: Differential subcellular localization of SK3-containing channels in the hippocampus.
abstract: Small-conductance, Ca(2+) -activated K(+) (SK) channels are expressed in the hippocampus where they regulate synaptic responses, plasticity, and learning and memory. To investigate the expression of SK3 (KCNN3) subunits, we determined the developmental profile and subcellular distribution of SK3 in the developing mouse hippocampus using western blots, immunohistochemistry and high-resolution immunoelectron microscopy. The results showed that SK3 expression increased during postnatal development, and that the localization of SK3 changed from being mainly associated with the endoplasmic reticulum and intracellular sites during the first postnatal week to being progressively concentrated in dendritic spines during later stages. In the adult, SK3 was localized mainly in postsynaptic compartments, both at extrasynaptic sites and along the postsynaptic density of excitatory synapses. Double labelling showed that SK3 co-localized with SK2 (KCNN2) and with N-methyl-D-aspartate receptors. Finally, quantitative analysis of SK3 density revealed two subcellular distribution patterns in different hippocampal layers, with SK3 being unevenly distributed in CA1 region of the hippocampus pyramidal cells and homogeneously distributed in dentate gyrus granule cells. Our results revealed a complex cell surface distribution of SK3-containing channels and a distinct developmental program that may influence different hippocampal functions.
authors.affiliation: Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, Albacete, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Ballesteros-Merino
authors.affiliation: Department of Anatomy, Hokkaido University School of Medicine, Sapporo, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Watanabe
authors.affiliation: Division of Cerebral Structure, National Institute for Physiological Sciences, Okazaki, Japan.
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Shigemoto
authors.affiliation: Division of Cerebral Structure, National Institute for Physiological Sciences, Okazaki, Japan.
authors.forename: Yugo
authors.initials: Y
authors.lastname: Fukazawa
authors.affiliation: Vollum Institute, Oregon Health & Science University, Portland, OR, USA.
authors.forename: John P
authors.initials: JP
authors.lastname: Adelman
authors.affiliation: Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, Albacete, Spain.
authors.forename: Rafael
authors.initials: R
authors.lastname: Luján
mesh_terms: D000818:Animals; D056547:CA1 Region, Hippocampal / Q000254:growth & development / Q000378:metabolism*; D003712:Dendrites / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D051379:Mice; D009928:Organ Specificity; D057907:Post-Synaptic Density / Q000378:metabolism*; D021381:Protein Transport; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics / Q000378:metabolism; D051640:Small-Conductance Calcium-Activated Potassium Channels / Q000235:genetics / Q000378:metabolism*
chemical_list: C496898:Kcnn2 protein, mouse; C496900:Kcnn3 protein, mouse; D016194:Receptors, N-Methyl-D-Aspartate; D051640:Small-Conductance Calcium-Activated Potassium Channels
keywords: cell surface distribution; development; electron microscopy; immunohistochemistry; mouse; potassium channel