Mu opioid receptor activation of ERK1/2 is GRK3 and arrestin dependent in striatal neurons

J Biol Chem. 2006 Nov 10;281(45):34515-24. doi: 10.1074/jbc.M604278200. Epub 2006 Sep 18.

Abstract

In this study we investigated the mechanisms responsible for MAP kinase ERK1/2 activation following agonist activation of endogenous mu opioid receptors (MOR) normally expressed in cultured striatal neurons. Treatment with the MOR agonist fentanyl caused significant activation of ERK1/2 in neurons derived from wild type mice. Fentanyl effects were blocked by the opioid antagonist naloxone and were not evident in neurons derived from MOR knock-out (-/-) mice. In contrast, ERK1/2 activation by fentanyl was not evident in neurons from GRK3-/- mice or neurons pretreated with small inhibitory RNA for arrestin3. Consistent with this observation, treatment with the opiate morphine (which is less able to activate arrestin) did not elicit ERK1/2 activation in wild type neurons; however, transfection of arrestin3-(R170E) (a dominant positive form of arrestin that does not require receptor phosphorylation for activation) enabled morphine activation of ERK1/2. In addition, activation of ERK1/2 by fentanyl and morphine was rescued in GRK3-/- neurons following transfection with dominant positive arrestin3-(R170E). The activation of ERK1/2 appeared to be selective as p38 MAP kinase activation was not increased by either fentanyl or morphine treatment in neurons from wild type, MOR-/-, or GRK3-/- mice. In addition, U0126 (a selective inhibitor of MEK kinase responsible for ERK phosphorylation) blocked ERK1/2 activation by fentanyl. These results support the hypothesis that MOR activation of ERK1/2 requires opioid receptor phosphorylation by GRK3 and association of arrestin3 to initiate the cascade resulting in ERK1/2 phosphorylation in striatal neurons.

Publication types

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

MeSH terms

  • Animals
  • Arrestins / antagonists & inhibitors
  • Arrestins / genetics
  • Arrestins / metabolism*
  • Cells, Cultured
  • Corpus Striatum / cytology
  • Corpus Striatum / metabolism*
  • Corpus Striatum / ultrastructure
  • Enzyme Activation / drug effects
  • Fentanyl / pharmacology
  • G-Protein-Coupled Receptor Kinase 3
  • Immunoblotting
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mitogen-Activated Protein Kinase 1 / metabolism*
  • Mitogen-Activated Protein Kinase 3 / metabolism*
  • Naloxone / pharmacology
  • Narcotic Antagonists
  • Neurons / cytology
  • Neurons / metabolism*
  • Neurons / ultrastructure
  • Phosphorylation / drug effects
  • RNA, Small Interfering / pharmacology
  • Receptors, Opioid, mu / chemistry
  • Receptors, Opioid, mu / genetics
  • Receptors, Opioid, mu / physiology*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Transfection
  • beta-Adrenergic Receptor Kinases / genetics
  • beta-Adrenergic Receptor Kinases / physiology*

Substances

  • Arrestins
  • Narcotic Antagonists
  • RNA, Small Interfering
  • Receptors, Opioid, mu
  • arrestin3
  • Naloxone
  • G-Protein-Coupled Receptor Kinase 3
  • GRK3 protein, mouse
  • beta-Adrenergic Receptor Kinases
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Fentanyl