Inhibition of Transient Receptor Potential Melastatin 3 ion channels by G-protein βγ subunits

Elife. 2017 Aug 15;6:e26147. doi: 10.7554/eLife.26147.

Abstract

Transient receptor potential melastatin 3 (TRPM3) channels are activated by heat, and chemical ligands such as pregnenolone sulphate (PregS) and CIM0216. Here, we show that activation of receptors coupled to heterotrimeric Gi/o proteins inhibits TRPM3 channels. This inhibition was alleviated by co-expression of proteins that bind the βγ subunits of heterotrimeric G-proteins (Gβγ). Co-expression of Gβγ, but not constitutively active Gαi or Gαo, inhibited TRPM3 currents. TRPM3 co-immunoprecipitated with Gβ, and purified Gβγ proteins applied to excised inside-out patches inhibited TRPM3 currents, indicating a direct effect. Baclofen and somatostatin, agonists of Gi-coupled receptors, inhibited Ca2+ signals induced by PregS and CIM0216 in mouse dorsal root ganglion (DRG) neurons. The GABAB receptor agonist baclofen also inhibited inward currents induced by CIM0216 in DRG neurons, and nocifensive responses elicited by this TRPM3 agonist in mice. Our data uncover a novel signaling mechanism regulating TRPM3 channels.

Keywords: DRG neuron; G-protein; TRPA1; TRPM3; TRPM8; mouse; neuroscience; sensory ion channel.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Baclofen / antagonists & inhibitors
  • Behavior Rating Scale
  • Calcium / metabolism
  • GTP-Binding Protein alpha Subunits, Gi-Go / metabolism
  • GTP-Binding Protein alpha Subunits, Gi-Go / pharmacology
  • GTP-Binding Protein beta Subunits / pharmacology*
  • GTP-Binding Protein gamma Subunits / pharmacology*
  • Ganglia, Spinal / drug effects
  • Ganglia, Spinal / metabolism
  • HEK293 Cells
  • Heterocyclic Compounds, 4 or More Rings / pharmacology
  • Humans
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Mice
  • Neurons / drug effects
  • Neurons / metabolism
  • Pregnenolone / pharmacology
  • Somatostatin / antagonists & inhibitors
  • TRPM Cation Channels / drug effects*

Substances

  • CIM0216
  • G-protein Beta gamma
  • GINIP protein, rat
  • GTP-Binding Protein beta Subunits
  • GTP-Binding Protein gamma Subunits
  • Heterocyclic Compounds, 4 or More Rings
  • Intracellular Signaling Peptides and Proteins
  • TRPM Cation Channels
  • TRPM3 protein, mouse
  • pregnenolone sulfate
  • Somatostatin
  • Pregnenolone
  • GNAO1 protein, mouse
  • GTP-Binding Protein alpha Subunits, Gi-Go
  • Baclofen
  • Calcium