Nicotine exploits a COPI-mediated process for chaperone-mediated up-regulation of its receptors

J Gen Physiol. 2014 Jan;143(1):51-66. doi: 10.1085/jgp.201311102.

Abstract

Chronic exposure to nicotine up-regulates high sensitivity nicotinic acetylcholine receptors (nAChRs) in the brain. This up-regulation partially underlies addiction and may also contribute to protection against Parkinson's disease. nAChRs containing the α6 subunit (α6* nAChRs) are expressed in neurons in several brain regions, but comparatively little is known about the effect of chronic nicotine on these nAChRs. We report here that nicotine up-regulates α6* nAChRs in several mouse brain regions (substantia nigra pars compacta, ventral tegmental area, medial habenula, and superior colliculus) and in neuroblastoma 2a cells. We present evidence that a coat protein complex I (COPI)-mediated process mediates this up-regulation of α6* or α4* nAChRs but does not participate in basal trafficking. We show that α6β2β3 nAChR up-regulation is prevented by mutating a putative COPI-binding motif in the β3 subunit or by inhibiting COPI. Similarly, a COPI-dependent process is required for up-regulation of α4β2 nAChRs by chronic nicotine but not for basal trafficking. Mutation of the putative COPI-binding motif or inhibition of COPI also results in reduced normalized Förster resonance energy transfer between α6β2β3 nAChRs and εCOP subunits. The discovery that nicotine exploits a COPI-dependent process to chaperone high sensitivity nAChRs is novel and suggests that this may be a common mechanism in the up-regulation of nAChRs in response to chronic nicotine.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Animals
  • Binding Sites
  • Brain / drug effects
  • Brain / metabolism
  • Cell Line, Tumor
  • Coat Protein Complex I / metabolism*
  • Mice
  • Nicotine / pharmacology*
  • Nicotinic Agonists / pharmacology*
  • Protein Binding
  • Protein Subunits / chemistry
  • Protein Subunits / genetics
  • Protein Subunits / metabolism
  • Protein Transport
  • Receptors, Nicotinic / chemistry
  • Receptors, Nicotinic / genetics
  • Receptors, Nicotinic / metabolism*
  • Up-Regulation*

Substances

  • Coat Protein Complex I
  • Nicotinic Agonists
  • Protein Subunits
  • Receptors, Nicotinic
  • Nicotine