Functional role of conserved amino acid residues in the intracellular domain of α7 acetylcholine receptors.

Abstract

The α7 nicotinic acetylcholine receptor (nAChR) is a pentameric ligand-gated ion channel (pLGIC). It is expressed in pivotal brain regions and plays critical roles in the central nervous system and in the cholinergic inflammatory pathway. Their activation by the endogenous acetylcholine leads to signal transmission in the nervous system. Deficits in α7 function are associated with mental illnesses such as schizophrenia and degenerative conditions such as Alzheimer's disease. In the cholinergic anti-inflammatory pathway, binding of ligands to α7 nAChRs attenuates inflammation and may play a role in preventing the cytokine storm during SARS-CoV-2 infection. Undesired effects of nicotine binding to α7 nAChRs include proliferation, angiogenesis, and metastasis in lung cell carcinoma. In summary, the α7 nAChR has great potential as a therapeutic target. Current drug candidates for pGLICs in general bind to the extracellular domain (ECD) and transmembrane domain (TMD) of the receptor that are highly-homologous in this large super-family comprising more than 40 subunits in humans. Since the largest number of subunits belong to the nAChR family, interactions with off-target subunits, and consequently undesired effects are likely for ligands binding to the highly-conserved ECD or TMD. An understanding of the mechanism of action of α7 nAChR and of proteins affecting its activity may facilitate development of targeted therapies. Functional expression and properties of nAChRs have been shown to be affected by Resistance to Inhibitors of Cholinesterase-3 (RIC-3). Here, we explore the interaction of the intracellular domain (ICD) of α7 nAChR and cytoplasmic protein RIC-3 chaperon which mediates functional expression of the channel. Using synthetic peptides, the molecular interaction between α7 nAChRs and RIC-3 will be characterized, and the results will be substantiated using full-length α7 nAChRs in electrophysiological experiments after heterologous expression.