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Objectives: To provide insight into the biological effects of activated Yes-associated protein (YAP) on the proliferation, apoptosis, and senescence of human periodontal ligament stem cells (h-PDLSCs).Methods: h-PDLSCs were isolated by the limiting dilution method, and their surface markers were quantified by flow cytometry. Enhanced green fluorescence protein (EGFP)-labeled lentiviral vector was used to activate YAP in h-PDLSCs, then qRT-PCR and Western blotting were used to evaluate the expression level of YAP. Immunofluorescence was used to detect the location of YAP in h-PDLSCs. The proliferation activity was detected by cell counting kit-8 (CCK-8) and 5-ethynyl-2'-deoxyuridine (EdU), and the cell cycle was determined by flow cytometry. Apoptosis was analyzed by Annexin V-APC staining. Cell senescence was detected by β-galactosidase staining. Proteins in ERK, Bcl-2, and p53 signaling pathways were detected by Western blotting.Results: h-PDLSCs were isolated successfully and were positive for human mesenchymal stem cell surface markers. After YAP was activated by lentiviral vector, the mRNA and protein of YAP were highly expressed, and more YAP translocated into the nucleus. When YAP was overexpressed in h-PDLSCs, proliferation activity was improved; early and late apoptosis rates decreased (P<0.05); the proportion of cells in G2/M phases increased (P<0.05), while that in G0/G1 phase decreased (P<0.05); cellular senescence was delayed (P<0.01); the expression of P-MEK, P-ERK, P-P90RSK and P-Msk increased, while the expression of Bcl-2 family members (Bak, Bid and Bik) decreased.Conclusions: Activated YAP promotes proliferation, inhibits apoptosis, and delays senescence of h-PDLSCs. The Hippo-YAP signaling pathway can influence ERK and Bcl-2 signaling pathways.

Human periodontal ligament stem cells (PDLSCs), a type of dental tissue–derived mesenchymal stem cells (MSCs), can be clinically applied in periodontal tissue regeneration to treat periodontitis, which is initiated and sustained by bacteria. Lipopolysaccharide (LPS), the major component of the outer membrane of gram‐negative bacteria, is a pertinent deleterious factor in the oral microenvironment. The aim of this study was to investigate the effect of LPS on the proliferation and osteogenic differentiation of PDLSCs, as well as the mechanisms involved. Proliferation and osteogenic differentiation of PDLSCs were detected under the stimulation of Escherichia coli–derived LPS. The data showed that E. coli–derived LPS did not affect the proliferation, viability, and cell cycle of PDLSCs. Furthermore, it promoted osteogenic differentiation with the activation of TAZ. Lentivirus‐mediated depletion of TAZ (transcriptional activator with a PDZ motif) was used to determine the role of TAZ on LPS‐induced enhancement of osteogenesis. PDLSCs cultured in osteogenic media with or without LPS and DKK1 (Wnt/β‐catenin pathway inhibitor) were used to determine the regulatory effect of Wnt signaling. We found that TAZ depletion offset LPS‐induced enhancement of osteogenesis. Moreover, treatment with DKK1 offset LPS‐induced TAZ elevation and osteogenic promotion. In conclusion, E. coli–derived LPS promoted osteogenic differentiation of PDLSCs by fortifying TAZ activity. The elevation and activation of TAZ were mostly mediated by the Wnt/β‐catenin pathway. PDLSC‐governed alveolar bone tissue regeneration was not necessarily reduced under bacterial conditions and could be modulated by Wnt and TAZ.

Rutin is one of the flavonoids found in fruits and vegetables. Recent reports have revealed that rutin is a major player in proliferation and bone development. However, data on how rutin regulates the proliferation of periodontal ligament stem cells (PDLSCs), as well as the differentiation of osteogenic cells are scanty. Here, our findings showed that rutin enhanced PDLSCs proliferation, increased ALP activity, and matrix mineralization. Moreover, rutin significantly promoted the expression of osteogenic genes and elevated phosphorylated AKT and mTOR. Treatment with LY294002 reversed these effects by inhibiting PI3K. We also found that the expression levels of GPR30 were increased by rutin. Interestingly, this upregulation was not altered after the addition of LY294002. In addition, G15, a selective antagonist of GPR30, could reduce the beneficial effects induced by rutin and interfere with the modulation of PI3K/AKT/mTOR signal transduction. Collectively, our findings revealed that rutin increased proliferation and osteogenic differentiation of PDLSCs through GPR30-mediated PI3K/AKT/mTOR signal transduction. Therefore, it could be deduced that rutin as a certain flavonoid possesses therapeutic value for periodontal bone regeneration and tissue engineering. Impact statement In our study, the effects and mechanisms of rutin on the osteogenic differentiation and proliferation of PDLSCs were investigated. Our findings might provide basic knowledge and guidance to understand and use rutin in the bioengineering of the periodontal tissues and regeneration of bones. The following is a short description of the main findings: rutin promotes the osteogenic differentiation and proliferation of PDLSCs; PI3K/AKT/mTOR signal pathway mediates the effects of rutin on PDLSCs; rutin activates PI3K/AKT/mTOR signal pathway via GPR30.