Involvement of Parkin in the ubiquitin proteasome system-mediated degradation of N-type voltage-gated Ca2+ channels

PLoS One. 2017 Sep 28;12(9):e0185289. doi: 10.1371/journal.pone.0185289. eCollection 2017.

Abstract

N-type calcium (CaV2.2) channels are widely expressed in the brain and the peripheral nervous system, where they play important roles in the regulation of transmitter release. Although CaV2.2 channel expression levels are precisely regulated, presently little is known regarding the molecules that mediate its synthesis and degradation. Previously, by using a combination of biochemical and functional analyses, we showed that the complex formed by the light chain 1 of the microtubule-associated protein 1B (LC1-MAP1B) and the ubiquitin-proteasome system (UPS) E2 enzyme UBE2L3, may interact with the CaV2.2 channels promoting ubiquitin-mediated degradation. The present report aims to gain further insights into the possible mechanism of degradation of the neuronal CaV2.2 channel by the UPS. First, we identified the enzymes UBE3A and Parkin, members of the UPS E3 ubiquitin ligase family, as novel CaV2.2 channel binding partners, although evidence to support a direct protein-protein interaction is not yet available. Immunoprecipitation assays confirmed the interaction between UBE3A and Parkin with CaV2.2 channels heterologously expressed in HEK-293 cells and in neural tissues. Parkin, but not UBE3A, overexpression led to a reduced CaV2.2 protein level and decreased current density. Electrophysiological recordings performed in the presence of MG132 prevented the actions of Parkin suggesting enhanced channel proteasomal degradation. Together these results unveil a novel functional coupling between Parkin and the CaV2.2 channels and provide a novel insight into the basic mechanisms of CaV channels protein quality control and functional expression.

MeSH terms

  • Animals
  • Calcium Channels, N-Type / metabolism*
  • Cell Membrane / metabolism
  • Ganglia, Spinal / metabolism
  • Gene Knockdown Techniques
  • HEK293 Cells
  • Humans
  • Ion Channel Gating
  • Mice, Inbred BALB C
  • Microtubule-Associated Proteins / metabolism
  • Proteasome Endopeptidase Complex / metabolism*
  • Protein Binding
  • Protein Subunits / metabolism
  • Proteolysis*
  • Rabbits
  • Rats
  • Recombinant Proteins / metabolism
  • Ubiquitin / metabolism*
  • Ubiquitin-Conjugating Enzymes / metabolism
  • Ubiquitin-Protein Ligases / metabolism*

Substances

  • Calcium Channels, N-Type
  • MAP1B protein, human
  • Microtubule-Associated Proteins
  • Protein Subunits
  • Recombinant Proteins
  • Ubiquitin
  • UBE2L3 protein, human
  • Ubiquitin-Conjugating Enzymes
  • UBE3A protein, human
  • Ubiquitin-Protein Ligases
  • parkin protein
  • Proteasome Endopeptidase Complex

Grants and funding

This work was entirely supported by funds from The National Council for Science and Technology (Conacyt, Mexico), grant 221660 to RF. There was no additional external funding received for this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.