title: Developmental profile of SK2 channel expression and function in CA1 neurons.
abstract: We investigated the temporal and spatial expression of SK2 in the developing mouse hippocampus using molecular and biochemical techniques, quantitative immunogold electron microscopy, and electrophysiology. The mRNA encoding SK2 was expressed in the developing and adult hippocampus. Western blotting and immunohistochemistry showed that SK2 protein increased with age. This was accompanied by a shift in subcellular localization. Early in development (P5), SK2 was predominantly localized to the endoplasmic reticulum in the pyramidal cell layer. But by P30 SK2 was almost exclusively expressed in the dendrites and spines. The level of SK2 at the postsynaptic density (PSD) also increased during development. In the adult, SK2 expression on the spine plasma membrane showed a proximal-to-distal gradient. Consistent with this redistribution and gradient of SK2, the selective SK channel blocker apamin increased evoked excitatory postsynaptic potentials (EPSPs) only in CA1 pyramidal neurons from mice older than P15. However, the effect of apamin on EPSPs was not different between synapses in proximal or distal stratum radiatum or stratum lacunosum-moleculare in adult. These results show a developmental increase and gradient in SK2-containing channel surface expression that underlie their influence on neurotransmission, and that may contribute to increased memory acquisition during early development.
authors.affiliation: Departamento de Ciencias Médicas, Instituto de Investigación en Discapacidades Neurológicas, Facultad de Medicina, Universidad Castilla-La Mancha, Albacete, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Ballesteros-Merino
authors.forename: Mike
authors.initials: M
authors.lastname: Lin
authors.forename: Wendy W
authors.initials: WW
authors.lastname: Wu
authors.forename: Clotilde
authors.initials: C
authors.lastname: Ferrandiz-Huertas
authors.forename: María J
authors.initials: MJ
authors.lastname: Cabañero
authors.forename: Masahiko
authors.initials: M
authors.lastname: Watanabe
authors.forename: Yugo
authors.initials: Y
authors.lastname: Fukazawa
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Shigemoto
authors.forename: James
authors.initials: J
authors.lastname: Maylie
authors.forename: John P
authors.initials: JP
authors.lastname: Adelman
authors.forename: Rafael
authors.initials: R
authors.lastname: Luján
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D056547:CA1 Region, Hippocampal / Q000166:cytology* / Q000254:growth & development* / Q000378:metabolism*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D051640:Small-Conductance Calcium-Activated Potassium Channels / Q000096:biosynthesis*; D013569:Synapses / Q000502:physiology
chemical_list: C496898:Kcnn2 protein, mouse; D051640:Small-Conductance Calcium-Activated Potassium Channels
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