The Mechanism Of YAP Negatively Regulates The Expression Of P21 Affecting The Chondrocyte Phenotype Senescence

Objective:The purpose of this study is to elucidate the role of YAP in maintaining the phenotype of chondrocytes by investigating the subcellular localization and expression of YAP in cartilage and chondrosarcoma,and the mechanism of YAP/p21 inhibiting cell proliferation and causing cell senescence was further explored.Finally,we explored the relationship between YAP/p21 and DNA damage or chemosensitivityMethod:1.Expression of YAP in cartilage and osteoarthritic tissues was detected by immunohistochemistry2.The role of YAP in cell proliferation was examined using CCK-8,Ed U and Colony formation assays3.The role of YAP in cell cycle and apoptosis was detected by flow cytometry4.Cyclins(p21,p27,P53,Cyclin D1,etc.),apoptosis-related proteins(Cleaved Caspase-3,Bcl-x L and PARP),Hippo signing pathway proteins(YAP,TAZ,CYR61,etc.),DNA damage related proteins(γ-H2 AX,H2AX,etc.),cell senescence-associated protein(p16),and other related proteins were detected by western blotting5.The localization of YAP in chondrocytes(CHON-001)and chondrosarcoma cell lines(SW 1353 and Hs 819.T)was detected by immunofluorescence6.Using aging-related β-galactosidase staining assay to detect cell aging7.The role of YAP/p21 in tumor growth was investigate by xenograft tumor experiments in vivo8.Using small interfering RNA(si RNA)and YAP lentivirus-mediated sh RNA to knockdown YAP expression combined with overexpression of YAP by HA plasmid demonstrated that YAP plays an essential role in the above experiments9.Detection of DNA damage by comet assayResults:1.The growth of chondrosarcoma requires the expression of nuclear YAP2.YAP / TEAD mediates cell cycle arrest and induces cell senescence3.Growth inhibition by YAP depletion is correlated with p21 expression in vivo4.YAP depletion is involved in DNA damage and required for sensitization of chemotherapy5.YAP regulates p21 expression and senescence via a p53 and Sp1 independent manner6.A sequential targeting oncogenic YAP and p21 promotes elimination of therapy-induced senescent cellsConclusion:1.YAP plays an important role in chondrosarcoma,knocking down the expression of YAP causes G1 phase cell cycle arrest,apoptosis and cell senescence of chondrosarcoma cells2.YAP induces cell growth inhibition and cell senescence by negatively regulating p21 expression in vitro and in vivo3.YAP induces DNA damage response and increases the sensitivity of chemotherapeutic drugs by negatively regulating p21...