Identification and characterization of a novel, shorter isoform of the small conductance Ca2+ -activated K+ channel SK2 |
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Authors: | Murthy Saravana R K Teodorescu Georgeta Nijholt Ingrid M Dolga Amalia M Grissmer Stephan Spiess Joachim Blank Thomas |
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Affiliation: | Max Planck Institute for Experimental Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii 96813, USA. |
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Abstract: | Throughout the CNS, small conductance Ca(2+)-activated potassium (SK) channels modulate firing frequency and neuronal excitability. We have identified a novel, shorter isoform of standard SK2 (SK2-std) in mouse brain which we named SK2-sh. SK2-sh is alternatively spliced at exon 3 and therefore lacks 140 amino acids, which include transmembrane domains S3, S4 and S5, compared with SK2-std. Western blot analysis of mouse hippocampal tissue revealed a 47 kDa protein product as predicted for SK2-sh along with a 64 kDa band representing the standard SK2 isoform. Electrophysiological recordings from transiently expressed SK2-sh revealed no functional channel activity or interaction with SK2-std. With the help of real-time PCR, we found significantly higher expression levels of SK2-sh mRNA in cortical tissue from AD cases when compared with age-matched controls. A similar increase in SK2-sh expression was induced in cortical neurons from mice by cytokine exposure. Substantial clinical evidence suggests that excess cytokines are centrally involved in the pathogenesis of Alzheimer's disease. Thus, SK2-sh as a downstream target of cytokines, provide a promising target for additional investigation regarding potential therapeutic intervention. |
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Keywords: | Alzheimer’s disease cortical neurons small conductance calcium‐activated potassium channel splice variant whole‐cell recordings |
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