Molecular and pharmacological investigation of alpha 7 nicotinic acetylcholine receptors in human induced pluripotent stem cell-derived dentate gyrus granule cells

Background Nicotinic acetylcholine receptors (nAChRs) are expressed throughout the mammalian central nervous system, mediating cholinergic neurotransmission both in the developing and the adult brain. Among these, alpha 7 (α7) nAChRs demonstrate unique pharmacological properties and are potential targets in the treatment of neuropsychiatric disorders. α7nAChRs are also present in the hippocampus, therefore, we investigated this receptor type in human induced pluripotent stem cell (hiPSC) derived dentate gyrus (DG) granule cells, an in vitro model system of adult hippocampal neurogenesis. Methods DG granule cells were generated from hiPSCs to investigate the nAChR α7 subunit expression via qPCR, RNA-sequencing, and bungarotoxin-staining. To validate receptor function, we employed single-neuron patch-clamp electrophysiology. Calcium-imaging was used to assess spontaneous and ligand-evoked calcium-transients, while multi-electrode array (MEA) measurements were applied to evaluate network activity. Experiments involved choline (agonist), PNU-120596 (allosteric activator), and methyllaconitine (antagonist). Results Our results showed α7nAChRs in hiPSCs-derived PROX1 and MAP2 positive DG granule cells. Patch-clamp electrophysiology revealed that the selective agonist choline evoked inward currents, which were greatly augmented by PNU-120596. Methyllycaconitine inhibited these currents. Ca-imaging showed increased transients in response to both choline and PNU-120596, which were blocked by methyllycaconitine. MEA recordings indicated increased bursting activity with choline, but not with PNU-120596. Conclusion Our results suggest that hiPSC-derived DG granule cells are amenable to functional assays to investigate α7nAChR function and pharmacology. This model system can serve for testing the receptor in a neuronal population relevant for several psychiatric disorders, including schizophrenia, anxiety disorders, and Alzheimer’s disease.