Yap-Regulated Er Stress Promotes Dentin Formation And Odontoblast Differentiation

This study aimed to investigate whether endoplasmic reticulum (ER) stress mediated by Yes-associated protein (YAP) plays a role during dentin formation and odontoblast differentiation in dental pulp stem cells (DPSCs). The study was approved by the University’s Institutional Animal Care and Use Committee. In Sprague-Dawley (SD) rat mandibular first molars, YAP and ER stress markers (GRP78, GRP94) were detected via immunohistochemistry during dentin development. The role of YAP in the odontoblast differentiation of DPSCs was assessed using alkaline phosphatase staining, quantitative real-time polymerase chain reaction, western blot and immunofluorescence. YAP’s effects on differentiation and ERS stress were explored with a YAP inhibitor and lentiviral YAP overexpression (YAPOE). Calcium ion influx and ER stress levels were measured by transmission electron microscope and fluorescence assays. Additionally, a subcutaneous implantation model with YAPOE DPSCs/β-TCP scaffolds was established to verify YAP’s function in odontoblast differentiation in vivo. The expression levels of YAP, GRP78, and GRP94 exhibited a time-dependent increase in the odontoblast layer from postnatal day 1 (PN1) to 7, followed by a decrease from PN7 to 21. YAP positively regulates ER stress to modulate the odontoblast differentiation of DPSCs in vitro. In vivo, YAP overexpression in DPSCs triggered ER stress to facilitate odontoblast differentiation. YAP-driven ER stress emerges as a critical regulatory axis orchestrating dentin formation and odontoblast differentiation, thereby presenting a novel paradigm for dentin regeneration.