title: Small-conductance calcium-activated potassium type 2 channels (SK2, KCa2.2) in human brain.
abstract: SK2 (KCa2.2) channels are voltage-independent Ca2+-activated K+channels that regulate neuronal excitability in brain regions important for memory formation. In this study, we investigated the distribution and expression of SK2 channels in human brain by Western blot analysis and immunohistochemistry. Immunoblot analysis of human brain indicated expression of four distinct SK2 channel isoforms: the standard, the long and two short isoforms. Immunohistochemistry in paraffin-embedded post-mortem brain sections was performed in the hippocampal formation, amygdala and neocortex. In hippocampus, SK2-like immunoreactivity could be detected in strata oriens and radiatum of area CA1-CA2 and in the molecular layer. In the amygdala, SK2-like immunoreactivity was highest in the basolateral nuclei, while in neocortex, staining was mainly found enriched in layer V. Activation of SK2 channels is thought to regulate neuronal excitability in brain by contributing to the medium afterhyperpolarization. However, SK2 channels are blocked by apamin with a sensitivity that suggests heteromeric channels. The herein first shown expression of SK2 human isoform b in brain could explain the variability of electrophysiological findings observed with SK2 channels.
authors.affiliation: Department of Psychiatry, Psychotherapy and Psychosomatics, Medical University Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria. michael.willis@i-med.ac.at.
authors.forename: Michael
authors.initials: M
authors.lastname: Willis
authors.affiliation: Division of Molecular and Cellular Pharmacology, Medical University Innsbruck, Peter Mayr Strasse 1, 6020, Innsbruck, Austria.
authors.forename: Maria
authors.initials: M
authors.lastname: Trieb
authors.affiliation: Division of Molecular and Cellular Pharmacology, Medical University Innsbruck, Peter Mayr Strasse 1, 6020, Innsbruck, Austria.
authors.forename: Irmgard
authors.initials: I
authors.lastname: Leitner
authors.affiliation: Division of Molecular and Cellular Pharmacology, Medical University Innsbruck, Peter Mayr Strasse 1, 6020, Innsbruck, Austria.
authors.forename: Georg
authors.initials: G
authors.lastname: Wietzorrek
authors.affiliation: Department of Psychiatry and Psychotherapy A, Landeskrankenhaus Hall in Tirol, Milser Strasse 10, 6060, Hall in Tirol, Austria.
authors.forename: Josef
authors.initials: J
authors.lastname: Marksteiner
authors.affiliation: Division of Molecular and Cellular Pharmacology, Medical University Innsbruck, Peter Mayr Strasse 1, 6020, Innsbruck, Austria.
authors.forename: Hans-Günther
authors.initials: HG
authors.lastname: Knaus
mesh_terms: D000368:Aged; D000818:Animals; D001921:Brain / Q000378:metabolism*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000378:metabolism; D020033:Protein Isoforms / Q000378:metabolism; D051640:Small-Conductance Calcium-Activated Potassium Channels / Q000276:immunology / Q000378:metabolism*
chemical_list: C496897:KCNN2 protein, human; D020033:Protein Isoforms; D051640:Small-Conductance Calcium-Activated Potassium Channels
keywords: Afterhyperpolarization; Isoform; KCNN2