Somatodendritic surface expression of epitope-tagged and KChIP binding-deficient Kv4.2 channels in hippocampal neurons

PLoS One. 2018 Jan 31;13(1):e0191911. doi: 10.1371/journal.pone.0191911. eCollection 2018.

Abstract

Kv4.2 channels mediate a subthreshold-activating somatodendritic A-type current (ISA) in hippocampal neurons. We examined the role of accessory Kv channel interacting protein (KChIP) binding in somatodendritic surface expression and activity-dependent decrease in the availability of Kv4.2 channels. For this purpose we transfected cultured hippocampal neurons with cDNA coding for Kv4.2 wild-type (wt) or KChIP binding-deficient Kv4.2 mutants. All channels were equipped with an externally accessible hemagglutinin (HA)-tag and an EGFP-tag, which was attached to the C-terminal end. Combined analyses of EGFP self-fluorescence, surface HA immunostaining and patch-clamp recordings demonstrated similar dendritic trafficking and functional surface expression for Kv4.2[wt]HA,EGFP and the KChIP binding-deficient Kv4.2[A14K]HA,EGFP. Coexpression of exogenous KChIP2 augmented the surface expression of Kv4.2[wt]HA,EGFP but not Kv4.2[A14K]HA,EGFP. Notably, activity-dependent decrease in availability was more pronounced in Kv4.2[wt]HA,EGFP + KChIP2 coexpressing than in Kv4.2[A14K]HA,EGFP + KChIP2 coexpressing neurons. Our results do not support the notion that accessory KChIP binding is a prerequisite for dendritic trafficking and functional surface expression of Kv4.2 channels, however, accessory KChIP binding may play a potential role in Kv4.2 modulation during intrinsic plasticity processes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials
  • Animals
  • Cells, Cultured
  • Dendrites / metabolism
  • Epitopes / genetics
  • Epitopes / metabolism
  • Hippocampus / cytology
  • Hippocampus / metabolism*
  • Humans
  • Immunohistochemistry
  • Kv Channel-Interacting Proteins / genetics
  • Kv Channel-Interacting Proteins / metabolism*
  • Mutant Proteins / chemistry
  • Mutant Proteins / genetics
  • Mutant Proteins / metabolism
  • Neurons / metabolism
  • Patch-Clamp Techniques
  • Protein Binding
  • Rats
  • Rats, Wistar
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Shal Potassium Channels / chemistry
  • Shal Potassium Channels / genetics
  • Shal Potassium Channels / metabolism*
  • Transfection

Substances

  • Epitopes
  • KCNIP2 protein, human
  • Kv Channel-Interacting Proteins
  • Mutant Proteins
  • Recombinant Fusion Proteins
  • Shal Potassium Channels

Grants and funding

This work was supported by grants SFB444-A8 and BA2055/4-1 from the Deutsche Forschungsgemeinschaft (http://www.dfg.de/) to RB.