Abstract:
Nicotinic acetylcholine receptors (nAChRs) belong to ligand-gated ion channel receptors, of which
α7 nAChR subtype is widely distributed in the cerebral cortex, thalamus, hippocampus, and also identified in microglia, macrophages, bone marrow cells, etc. Previous studies revealed that
α7 nAChR is closely related to the function of the cholinergic anti-inflammatory pathway, and is a vital target for drug development of Alzheimer's disease and schizophrenia. The establishment of a stable
α7 nAChR
in vitro drug screening system is crucial for the efficient screening of novel drugs targeting this target. Recombinant expression of different subtypes of nAChRs on
Xenopus laevis oocyte membranes and current detected by two-electrode voltage clamp (TEVC) is an advanced and complex model for novel drug screening. Molecular chaperones can assist the assembly of some nAChR subunits to form functional receptors, providing a stable expression model for the screening of compounds targeting this receptor. In this study, a molecular chaperone gene of
α7 nAChR, transmembrane protein 35A (
Tmem35a), was isolated and cloned from rats. We constructed the recombinant expression vector and obtained the cRNA of
Tmem35a by
in vitro transcription technique. Two cRNAs (
Tmem35a and
α7) were mixed and injected into
X. laevis oocytes for expression. Then, the effects of this molecular chaperone on the current expression and pharmacological properties of
α7 nAChR were evaluated by the TEVC. The results revealed that TMEM35A, also known as novel acetylcholine receptor chaperone (NACHO) could effectively increase the expression of
α7 nAChR protein on oocyte membranes, and the amount of
α7 nAChR protein was increased about 1-fold. The peak current induced by agonist acetylcholine (ACh) was increased about 10-fold. After injection of
Tmem35a cRNA, the median effect concentration (EC
50) value of
α7 nAChR to agonist ACh is 228.5 μmol·L
-1, which shows almost no difference from native
α7 nAChR (EC
50: 223.3 μmol·L
-1), indicating the preservation of the normal properties of
α7 nAChR. The results of this investigation indicate that the molecular chaperone NACHO effectively assists the heterologous expression of
α7 nAChR in
X. laevis oocytes, which provides a model for screening the potency of lead compounds targeting
α7 nAChR. All animal experiments in this study were reviewed and approved by the Ethics Committee of Guangxi University (approval number: GXU-2023-0249).