Regulation of chondrocyte synthesis and catabolism by WW structural domain-containing transcrip-tion factor 1
Objective To investigate the role of WW structural domain-containing transcription factor 1(WWTR1 or TAZ)in the regulation of chondrocytes in post-traumatic osteoarthritis(PTOA).Methods Totally,20 c57bl/6 mice provided by the Animal Experiment Center of Guizhou Medical University were divided into the sham-operated(Sham)group and the medial meniscus(DMM)instability group by a simple randomization method,6 cases per group,and the knee joints were extracted 3 months later.The model was successfully constructed by employing hematoxylin and eosin(HE)staining and Saf-ranin O staining and grading of osteoarthritic cartilage damage according to the Osteoarthritis Research Soci-ety International(OARSI),and the expression of TAZ was detected by immunohistochemistry.Primary chondrocytes of the knee joint were isolated,cultured,and divided into control group and TAZ inhibitor group(TAZ inhibitor-1)for in vitro experiments.Then the effect of TAZ inhibitor-1 on TAZ expression in chondrocytes was detected by immunofluorescence.Western blotting assays and real-time quantitative poly-merase chain reaction(qPCR)were performed to detect the effect of TAZ inhibitor-1 on the expression of factors related to chondrocyte synthesis and catabolism.Comparisons between groups were made using the t-test.Results HE staining showed that the synovium was thickened and infiltrated with inflammatory cells in the DMM group compared to the control group.Safranin O staining showed that superficial articular carti-lage in the DMM had more degradation and thickening of the subchondral bone than the control group ac-cording to the the OARSI score(4.333±1.731 vs.1.000±0.167,t=21.240,P＜0.01).Immunohisto-chemical results showed that the TAZ expression was lower in the DMM group than in the control group(63.333±2.667 vs.44.500±1.500,t=19.210,P＜0.01).In vitro experiments,Immunofluorescence results showed that the expression of TAZ in chondrocytes in the TAZ inhibitor-1 group was lower than that in the control group(44.406±1.731 vs.54.772±5.419,t=15.860,P＜0.01).Western blotting re-sults showed that the expression of collagen alpha1,Co12,and collagen alpha1(Col2a1)in chondrocytes of the TAZ inhibitor-1 group was lower than that in the control group(44.406±1.731 vs.54.772±5.419,t=15.860,P＜0.01).The expression of Col2a1,and glycosaminoglycan(Aggrecan,ACAN)expression was lower in the TAZ inhibitor-1 group than that in the control group(0.470±0.038 vs.0.937±0.330,0.589±0.015 vs.0.859±0.037,t=20.830,17.160,P＜0.01).The expression of matrix metallopro-teinase-13(MMP-13),A Disintegrin and Metalloproteinase with Thrombospondin motifs(ADAMTS)-7 in the TAZ inhibitor-1 group was higher than that in the control group(0.897±0.004 vs.0.540±0.018,0.956±0.007 vs.0.605±0.013,t=4.920,8.056,P＜0.01).The qPCR results showed that the ex-pression of MMP-13,ADAMTS-7 and SRY-box transcription factor 5(SOX5)in the TAZ inhibitor-1 group was higher than in the control group(1.697±0.030 vs.1.000±0.007,5.242±0.343 vs.1.000±0.031,0.769±0.018 vs.1.000±0.030,t=22.820,23.010,12.270,P＜0.01),and the expression of genes such as COl2a1,ACAN,and hedgehog factor recombinant protein(IHH)in the TAZ inhibitor-1 group was lower than that in the control group(0.524±0.047 vs.1.001±0.069,0.664±0.310 vs.1.001±0.624,0.367±0.024 vs.1.002±0.085,t=10.580,8.875,13.660,P＜0.01).Conclusion TAZ promotes the development of PTOA in chondrocytes by regulating chondrocyte metabolism.
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