title: Localization of SK2 channels relative to excitatory synaptic sites in the mouse developing Purkinje cells.
abstract: Small-conductance, Ca(2+)-activated K(+) (SK) channels regulate neuronal excitability in a variety of ways. To understand their roles in different neuronal subtypes it is important to determine their precise subcellular distribution. Here, we used biochemical, light microscopy immunohistochemical and immunoelectron microscopy techniques, combined with quantitative approaches, to reveal the expression and subcellular localization patterns of SK2 in the developing cerebellum. Using western blots, the SK2 protein showed a progressive increase during postnatal development. At the light microscopic level, SK2 immunoreactivity was very prominent in the developing Purkinje cells (PC), particularly in the molecular layer (ML). Electron microscopy revealed that throughout development SK2 was mostly detected at the extrasynaptic and perisynaptic plasma membrane of dendritic shafts and dendritic spines of PCs. However, there was some localization at axon terminals as well. Quantitative analyses and 3D reconstructions further revealed a progressive developmental change of SK2 on the surface of PCs from dendritic shafts to dendritic spines. Together, these results indicate that SK2 channels undergo dynamic spatial regulation during cerebellar development, and this process is associated with the formation and maturation of excitatory synaptic contacts to PCs.
authors.affiliation: Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha Albacete, Albacete, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Ballesteros-Merino
authors.affiliation: Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha Albacete, Albacete, Spain.
authors.forename: José
authors.initials: J
authors.lastname: Martínez-Hernández
authors.affiliation: Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha Albacete, Albacete, Spain.
authors.forename: Carolina
authors.initials: C
authors.lastname: Aguado
authors.affiliation: Department of Anatomy, Hokkaido University School of Medicine Sapporo, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Watanabe
authors.affiliation: Vollum Institute, Oregon Health and 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 Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha Albacete, Albacete, Spain.
authors.forename: Rafael
authors.initials: R
authors.lastname: Luján
keywords: Purkinje Cells; SK2 channels; cerebellar development; electron microscopy; immunohistochemistry