Selective interactions of spinophilin with the C-terminal domains of the δ- and μ-opioid receptors and G proteins differentially modulate opioid receptor signaling

Cell Signal. 2012 Dec;24(12):2315-28. doi: 10.1016/j.cellsig.2012.08.002. Epub 2012 Aug 18.


Previous studies have shown that the intracellular domains of opioid receptors serve as platforms for the formation of a multi-component signaling complex consisting of various interacting partners (Leontiadis et al., 2009, Cell Signal. 21, 1218-1228; Georganta et al., 2010, Neuropharmacology, 59(3), 139-148). In the present study we demonstrate that spinophilin a dendritic-spine enriched scaffold protein associates with δ- and μ-opioid receptors (δ-ΟR, μ-OR) constitutively in HEK293 an interaction that is altered upon agonist administration and enhanced upon forskolin treatment for both μ-OR and δ-ΟR. Spinophilin association with the opioid receptors is mediated via the third intracellular loop and a conserved region of the C-terminal tails. The portion of spinophilin responsible for interaction with the δ-OR and μ-OR is narrowed to a region encompassing amino acids 151-444. Spinophilin, RGS4, Gα and Gβγ subunits of G proteins form a multi-protein complex using specific regions of spinophilin and a conserved amino acid stretch of the C-terminal tails of both δ-μ-ORs. Expression of spinophilin in HEK293 cells potentiated DPDPE-mediated adenylyl-cyclase inhibition of δ-OR leaving unaffected the levels of cAMP accumulation mediated by the μ-OR. Moreover, measurements of extracellular signal regulated kinase (ERK1,2) phosphorylation indicated that the presence of spinophilin attenuated agonist-driven ERK1,2 phosphorylation mediated upon activation of the δ-OR but not the μ-OR. Collectively, these findings suggest that spinophilin associates with both δ- and μ-ΟR and G protein subunits in HEK293 cells participating in a multimeric signaling complex that displays a differential regulatory role in opioid receptor signaling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenylyl Cyclases / metabolism
  • Colforsin / pharmacology
  • Cyclic AMP / metabolism
  • Enkephalin, D-Penicillamine (2,5)- / pharmacology
  • GTP-Binding Proteins / metabolism*
  • HEK293 Cells
  • Humans
  • Microfilament Proteins / genetics
  • Microfilament Proteins / metabolism*
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 3 / metabolism
  • Nerve Tissue Proteins / genetics
  • Nerve Tissue Proteins / metabolism*
  • Phosphorylation / drug effects
  • Protein Binding
  • Protein Structure, Tertiary
  • Protein Subunits / metabolism
  • Receptors, Opioid, delta / agonists
  • Receptors, Opioid, delta / metabolism*
  • Receptors, Opioid, mu / agonists
  • Receptors, Opioid, mu / metabolism*
  • Signal Transduction / drug effects


  • Microfilament Proteins
  • Nerve Tissue Proteins
  • Protein Subunits
  • Receptors, Opioid, delta
  • Receptors, Opioid, mu
  • neurabin
  • Colforsin
  • Enkephalin, D-Penicillamine (2,5)-
  • Cyclic AMP
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • GTP-Binding Proteins
  • Adenylyl Cyclases