1. School of Stomatology, Shandong University, Jinan, China
2. Department of Obstetrics and Gynecology, Qilu hospital of Shandong University, Jinan, China
3. Shandong provincial key laboratory of oral tissue regeneration, Jinan, China
4. School of Control Science and Engineering, Shandong University, Jinan, China
* co-first authors: These two authors contributed equally to this work and should be considered as co-first authors.
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.
Keywords: Yap, Cell Cycle, Apoptosis, Senescence, Human Periodontal Ligament Stem Cells