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• The polypeptide OP 3-4 promoted bone regeneration of mandibular defect. • OP 3-4 improved osteogenic differentiation of bone marrow mesenchymal stem cells. • OP 3-4 promoted osteogenic differentiation by AKT/GSK3β/β-catenin pathway. The aims of this study were to explore: (ⅰ) the effect of the polypeptide OP 3-4 on bone regeneration in vivo ; (ⅱ) the effect of OP 3-4 on osteogenic differentiation of bone marrow mesenchymal stem cells in vitro ; and (ⅲ) the potential mechanism of OP 3-4 in promoting osteogenic differentiation of bone marrow mesenchymal stem cells. 30 Wistar rats (8-week, male) were randomly divided into Control group (n = 5), Hydrogel group (n = 5), and Hydrogel loaded OP 3-4 group (n = 5). Hematoxylin and eosin staining was used to evaluate the level of bone regeneration in mandibular defect. Immunohistochemistry staining was used to evaluate the expression of alkaline phosphatase, runt-related transcription factor 2, and type Ⅰ collagen. Flow cytometry was applied to identify the phenotype of bone marrow mesenchymal stem cells. Furthermore, LY294002, the inhibitor of protein kinase B, was applied to verify the role of OP 3-4 in promoting osteogenic differentiation via protein kinase B/glycogen synthase kinase 3β/β-catenin pathway through western blot. OP 3-4 promoted bone regeneration of rat mandibular defect. The expression of osteogenic differentiation related markers were increased after adding OP 3-4 to bone marrow mesenchymal stem cells. OP 3-4 promoted osteogenic differentiation of bone marrow mesenchymal stem cells via protein kinase B/glycogen synthase kinase 3β/β-catenin pathway. OP 3-4 could promote bone regeneration of mandibular defect and improve osteogenic differentiation through protein kinase B/glycogen synthase kinase 3β/β-catenin pathway. [ABSTRACT FROM AUTHOR]

• Notum expression increased in gingival tissues. • Notum expression increased in periodontal ligament. • Notum inhibited human periodontal ligament stem cell (hPDLSC) osteogenesis. • Notum regulated hPDLSC osteogenesis through Wnt/beta-catentin signaling. The aims of this study were to explore: (ⅰ) the effect of Notum on periodontitis in vivo ; (ⅱ) the effect of Notum on the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) in vitro ; and (ⅲ) the potential mechanism of Notum in inhibiting the osteogenic differentiation of hPDLSCs. C57BL/6J mice were randomly assigned into two groups: control group (n = 4) and periodontitis group (n = 4). Immunohistochemical staining was used to evaluate the expression of Notum. In in vitro experiments, Western blot, qRT- PCR and ELISA were used to examine the expression of Notum in a lipopolysaccharide-induced inflammation model. Alkaline phosphatase staining was used to evaluate alkaline phosphatase activity. Western blot and qRT - PCR were used to measure the expression of osteogenic-related markers after adding human recombinant Notum and Notum inhibitor ABC99. In addition, LiCl, an agonist of the Wnt/Beta-catenin signaling pathway, was added to explore using Western blot whether Notum was involved in regulating the osteogenic differentiation of human periodontal ligament stem cells through the Wnt/Beta-catenin signaling pathway. Notum was highly expressed in periodontal tissues of mice and lipopolysaccharide-induced inflammation cell model. The protein and messenger ribonucleic acid levels of hPDLSCs osteogenic markers were reduced after adding human recombinant Notum. However, the inhibitory effect of Notum on the osteogenic differentiation of hPDLSCs could be significantly reversed by adding LiCl. These results demonstrated that Notum inhibited the osteogenic differentiation of hPDLSCs probably via the Wnt/Beta-catenin the downstream signaling pathway. [ABSTRACT FROM AUTHOR]