Ke Lu1,2, Tian-Shu Shi1,2, Si-Yu Shen1, Wan-Li Lu2, Jing Wu1, Kai-Jia Zhang1,2, Xiao-Bo Zhu1,2, Yong Shi1, Xiang-Lin Liu1, Fei Yu2, Lan Li2, Hua-Jian Teng2,3, Xiang Gao4, Huang-Xian Ju5, Wei Wang6, Chao-Jun Li1, Qing Jiang2,3, Bin Xue1,7,8. 1. State Key Laboratory of Pharmaceutical Biotechnology and Jiangsu Key Laboratory of Molecular Medicine, School of Medicine, Nanjing University Nanjing 210093, Jiangsu Province, P. R. China. 2. Department of Sports Medicine and Adult Reconstructive Surgery, Drum Tower Hospital, School of Medicine, Nanjing University Nanjing 210008, Jiangsu Province, P. R. China. 3. Joint Research Center for Bone and Joint Disease, Model Animal Research Center (MARC), Nanjing University Nanjing 210093, Jiangsu Province, P. R. China. 4. Key Laboratory of Model Animal for Disease Study of Ministry of Education, Model Animal Research Center, Nanjing University Nanjing 210093, Jiangsu Province, P. R. China. 5. MOE Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University Nanjing 210093, Jiangsu Province, P. R. China. 6. National Laboratory of Solid State Microstructures, Department of Physics, Nanjing University Nanjing 210093, Jiangsu Province, P. R. China. 7. State Key Laboratory of Natural Medicines, China Pharmaceutical University Nanjing 210009, Jiangsu Province, P. R. China. 8. Liver Disease Collaborative Research Platform of Medical School of Nanjing University Nanjing 210093, Jiangsu Province, P. R. China.
Abstract
BACKGROUND: This study is to investigate the effect of Egr1 on the mineralization and accumulation of chondrocyte extracellular matrix. METHODS: The femoral heads of patients of various heights were collected. Egr1 knockout mice were used. Their limb lengtha nd body weight were assessed. The bone characteristics were detected by micro-CT scan and histological staining. Immature murine articular chondrocytes (iMACs) were isolated. Gross morphology was observed by histological staining. Relevant mRNA and protein expression were detected by qRT-PCR and Western blot, respectively. the related proteins were observed by immunohistochemical staining and immunofluorescence assay. Chromatin immunoprecipitation and reporter gene assay were also used. TUNEL was used to detect apoptosis. RESULTS: It was found that shorter patients had reduced Egr1 expression levels in the hypertrophic cartilage zone of the femoral head. In addition, Egr1 knockout mice exhibited reduced body size. Micro-CT analysis showed that these mice also had reduced bone volume. Safranin-O staining showed that the extracellular matrix of these mice exhibited a relatively limited degree of mineralization, and TUNEL staining showed reduced cell apoptosis levels. After transfecting the iMACs with dominant-negative Egr1 adenoviruses to inhibit Egr1, the enzymes of Adamst4, Adamst5, Mmp3 and Mmp13 were significantly upregulated. ChIP and luciferase assays revealed that Egr1 might regulate the chondrocyte extracellular matrix by the PPARγ/RUNX2 signaling pathways. CONCLUSION: Egr1 has an important regulatory effect on the dynamic equilibrium of the chondrocyte extracellular matrix, which may be achieved through the PPARγ/RUNX2 signaling pathways.
BACKGROUND: This study is to investigate the effect of Egr1 on the mineralization and accumulation of chondrocyte extracellular matrix. METHODS: The femoral heads of patients of various heights were collected. Egr1 knockout mice were used. Their limb lengtha nd body weight were assessed. The bone characteristics were detected by micro-CT scan and histological staining. Immature murine articular chondrocytes (iMACs) were isolated. Gross morphology was observed by histological staining. Relevant mRNA and protein expression were detected by qRT-PCR and Western blot, respectively. the related proteins were observed by immunohistochemical staining and immunofluorescence assay. Chromatin immunoprecipitation and reporter gene assay were also used. TUNEL was used to detect apoptosis. RESULTS: It was found that shorter patients had reduced Egr1 expression levels in the hypertrophic cartilage zone of the femoral head. In addition, Egr1 knockout mice exhibited reduced body size. Micro-CT analysis showed that these mice also had reduced bone volume. Safranin-O staining showed that the extracellular matrix of these mice exhibited a relatively limited degree of mineralization, and TUNEL staining showed reduced cell apoptosis levels. After transfecting the iMACs with dominant-negative Egr1 adenoviruses to inhibit Egr1, the enzymes of Adamst4, Adamst5, Mmp3 and Mmp13 were significantly upregulated. ChIP and luciferase assays revealed that Egr1 might regulate the chondrocyte extracellular matrix by the PPARγ/RUNX2 signaling pathways. CONCLUSION:Egr1 has an important regulatory effect on the dynamic equilibrium of the chondrocyte extracellular matrix, which may be achieved through the PPARγ/RUNX2 signaling pathways.
Authors: F L Wang; J R Connor; R A Dodds; I E James; S Kumar; C Zou; M W Lark; M Gowen; M E Nuttall Journal: Osteoarthritis Cartilage Date: 2000-05 Impact factor: 6.576