Chemical chaperones exceed the chaperone effects of RIC-3 in promoting assembly of functional α7 AChRs

PLoS One. 2013 Apr 24;8(4):e62246. doi: 10.1371/journal.pone.0062246. Print 2013.


Functional α7 nicotinic acetylcholine receptors (AChRs) do not assemble efficiently in cells transfected with α7 subunits unless the cells are also transfected with the chaperone protein RIC-3. Despite the presence of RIC-3, large amounts of these subunits remain improperly assembled. Thus, additional chaperone proteins are probably required for efficient assembly of α7 AChRs. Cholinergic ligands can act as pharmacological chaperones to promote assembly of mature AChRs and upregulate the amount of functional AChRs. In addition, we have found that the chemical chaperones 4-phenylbutyric acid (PBA) and valproic acid (VPA) greatly increase the amount of functional α7 AChRs produced in a cell line expressing both α7 and RIC-3. Increased α7 AChR expression allows assay of drug action using a membrane potential-sensitive fluorescent indicator. Both PBA and VPA also increase α7 expression in the SH-SY5Y neuroblastoma cell line that endogenously expresses α7 AChRs. VPA increases expression of endogenous α7 AChRs in hippocampal neurons but PBA does not. RIC-3 is insufficient for optimal assembly of α7 AChRs, but provides assay conditions for detecting additional chaperones. Chemical chaperones are a useful pragmatic approach to express high levels of human α7 AChRs for drug selection and characterization and possibly to increase α7 expression in vivo.

Publication types

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

MeSH terms

  • Cell Line
  • Cell Membrane / metabolism
  • Cells, Cultured
  • Gene Expression
  • Gene Expression Regulation / drug effects
  • Humans
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Molecular Chaperones / metabolism
  • Molecular Chaperones / pharmacology
  • Protein Binding
  • Protein Multimerization* / drug effects
  • Protein Subunits / genetics
  • Protein Subunits / metabolism
  • alpha7 Nicotinic Acetylcholine Receptor / chemistry
  • alpha7 Nicotinic Acetylcholine Receptor / genetics
  • alpha7 Nicotinic Acetylcholine Receptor / metabolism*


  • Intracellular Signaling Peptides and Proteins
  • Molecular Chaperones
  • Protein Subunits
  • RIC3 protein, human
  • alpha7 Nicotinic Acetylcholine Receptor