α7 and β2 Nicotinic Acetylcholine Receptor Subunits Form Heteromeric Receptor Complexes that Are Expressed in the Human Cortex and Display Distinct Pharmacological Properties

PLoS One. 2015 Jun 18;10(6):e0130572. doi: 10.1371/journal.pone.0130572. eCollection 2015.

Abstract

The existence of α7β2 nicotinic acetylcholine receptors (nAChRs) has recently been demonstrated in both the rodent and human brain. Since α7-containing nAChRs are promising drug targets for schizophrenia and Alzheimer's disease, it is critical to determine whether α7β2 nAChRs are present in the human brain, in which brain areas, and whether they differ functionally from α7 nAChR homomers. We used α-bungarotoxin to affinity purify α7-containing nAChRs from surgically excised human temporal cortex, and found that α7 subunits co-purify with β2 subunits, indicating the presence of α7β2 nAChRs in the human brain. We validated these results by demonstrating co-purification of β2 from wild-type, but not α7 or β2 knock-out mice. The pharmacology and kinetics of human α7β2 nAChRs differed significantly from that of α7 homomers in response to nAChR agonists when expressed in Xenopus oocytes and HEK293 cells. Notably, α7β2 heteromers expressed in HEK293 cells display markedly slower rise and decay phases. These results demonstrate that α7 subunits in the human brain form heteromeric complexes with β2 subunits, and that human α7β2 nAChR heteromers respond to nAChR agonists with a unique pharmacology and kinetic profile. α7β2 nAChRs thus represent an alternative mechanism for the reported clinical efficacy of α7 nAChR ligands.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cerebral Cortex / metabolism*
  • Cerebral Cortex / pathology
  • Gene Expression Regulation / drug effects
  • HEK293 Cells
  • Humans
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Nicotinic Agonists / pharmacology
  • Nicotinic Antagonists / pharmacology
  • Oocytes / drug effects
  • Oocytes / metabolism
  • Patch-Clamp Techniques
  • Receptors, Nicotinic / deficiency
  • Receptors, Nicotinic / genetics
  • Receptors, Nicotinic / metabolism*
  • Xenopus laevis / growth & development
  • Xenopus laevis / metabolism
  • alpha7 Nicotinic Acetylcholine Receptor / deficiency
  • alpha7 Nicotinic Acetylcholine Receptor / genetics
  • alpha7 Nicotinic Acetylcholine Receptor / metabolism*

Substances

  • Nicotinic Agonists
  • Nicotinic Antagonists
  • Receptors, Nicotinic
  • alpha7 Nicotinic Acetylcholine Receptor
  • nicotinic receptor beta2

Grant support

This work was supported by the Danish Strategic Research Council (COGNITO, JDM), the Lundbeck Foundation (JDM), Eli Lilly and Company through the Lilly Research Award Program (JDM). The funder Eli Lilly and Company provided support in the form of salaries for authors RZ, DU, GG & ES, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.