(PO143) Orai1 Calcium Channel is a Novel Molecular Regulator of the Stemness in Dental Pulp Cells

Abstract: Orai1, a calcium channel involved in store-operated Ca2+ entry, plays a role in the osteogenic differentiation of adult mesenchymal cells. Three-dimensional spheres derived from dental pulp cells (DPCs) harbor a unique population of stem cells and exhibit enhanced capacity for differentiation. Nevertheless, the molecule responsible for regulating the stemness of DPC spheres remains elusive. Our objective is to investigate the impact of Orai1 on the preservation of stemness within DPCs. DPCs were cultured to investigate their stemness characteristics. Expression levels of genes were assessed through quantitative RT-PCR and Western analysis. Furthermore, the impact of Orai1 and its downstream target NFAT (nuclear factor of activated T cells) on the stemness of DPCs was evaluated through the use of inhibition techniques. Orai1 exhibited elevated expression levels in DPC spheres compared to DPC monolayer cells. Pharmacological and genetic inhibition of Orai1 resulted in the attenuation of stemness in DPCs, signifying the essential role of Orai1 in maintaining their stemness. The application of a chemical inhibitor targeting NFAT also diminished stemness attributes. Among the NFAT isoforms, NFATc2 had the most pronounced effect on the suppression of stemness. We noted a reduction in the expression levels of both Orai1 and NFATc2 in DPC spheres when subjected to serum-induced differentiation, indicating that the Orai1/NFATc2 axis serves as a novel molecular regulator. Our study revealed that the Orai1/NFATc2 signaling represents a novel molecular regulatory mechanism for preserving the stemness of DPCs. These findings suggest that enhancing this signaling pathway may present an effective opportunity for pulp tissue regeneration.