Phosphorylation sites on calcium channel alpha1 and beta subunits regulate ERK-dependent modulation of neuronal N-type calcium channels

Cell Calcium. 2006 Mar;39(3):275-92. doi: 10.1016/j.ceca.2005.11.002. Epub 2006 Jan 6.

Abstract

Voltage-dependent calcium channels (VDCCs) in sensory neurones are tonically up-regulated via Ras/extracellular signal regulated kinase (ERK) signalling. The presence of putative ERK consensus sites within the intracellular loop linking domains I and II of neuronal N-type (Ca(v)2.2) calcium channels and all four neuronal calcium channel beta subunits (Ca(v)beta), suggests that Ca(v)2.2 and/or Ca(v)betas may be ERK-phosphorylated. Here we report that GST-Ca(v)2.2 I-II loop, and to a lesser extent Ca(v)beta1b-His(6), are substrates for ERK1/2 phosphorylation. Serine to alanine mutation of Ser-409 and/or Ser-447 on GST-Ca(v)2.2 I-II loop significantly reduced phosphorylation. Loss of Ser-447 reduced phosphorylation to a greater extent than mutation of Ser-409. Patch-clamp recordings from wild-type Ca(v)2.2,beta1b,alpha2delta1 versus mutant Ca(v)2.2(S447A) or Ca(v)2.2(S409A) channels revealed that mutation of either site significantly reduced current inhibition by UO126, a MEK (ERK kinase)-specific inhibitor that down-regulates ERK activity. However, no additive effect was observed by mutating both residues together, suggesting some functional redundancy between these sites. Mutation of both Ser-161 and Ser-348 on Ca(v)beta1b did not significantly reduce phosphorylation but did reduce UO126-induced current inhibition. Crucially, co-expression of Ca(v)2.2(S447A) with Ca(v)beta1b(S161,348A) had an additive effect, abolishing the action of UO126 on channel current, an effect not seen when Ca(v)beta1b(S161,348A) was co-expressed with Ca(v)2.2(S409A). Thus, Ser-447 on Ca(v)2.2 and Ser-161 and Ser-348 of Ca(v)beta1b appear to be both necessary and sufficient for ERK-dependent modulation of these channels. Together, our data strongly suggest that modulation of neuronal N-type VDCCs by ERK involves phosphorylation of Ca(v)2.2alpha1 and to a lesser extent possibly also Ca(v)beta subunits.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Butadienes / pharmacology
  • COS Cells
  • Calcium Channels, L-Type / physiology
  • Calcium Channels, N-Type / genetics
  • Calcium Channels, N-Type / physiology*
  • Chlorocebus aethiops
  • Extracellular Signal-Regulated MAP Kinases / physiology*
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 3 / metabolism
  • Mitogen-Activated Protein Kinase Kinases / antagonists & inhibitors
  • Nitriles / pharmacology
  • Phosphorylation
  • Point Mutation
  • Rats
  • Serine / metabolism
  • Signal Transduction / physiology

Substances

  • Butadienes
  • Cacna1b protein, rat
  • Calcium Channels, L-Type
  • Calcium Channels, N-Type
  • L-type calcium channel alpha(1C)
  • Nitriles
  • U 0126
  • Serine
  • Extracellular Signal-Regulated MAP Kinases
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinase Kinases