M Sun1, S Hussain1, Y Hu1, J Yan1, Z Min1, X Lan1, Y Guo1, Y Zhao1, H Huang1, M Feng1, Y Han1, F Zhang1, W Zhu1, L Meng1, D Li1, J Sun2, S Lu3. 1. Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, PR China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an, Shaanxi, PR China. 2. Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, PR China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an, Shaanxi, PR China. Electronic address: sunjian1@mail.xjtu.edu.cn. 3. Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, PR China; Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an, Shaanxi, PR China. Electronic address: lushemin@mail.xjtu.edu.cn.
Abstract
OBJECTIVES: Selenium (Se) plays pivotal roles in maintaining optimal health. Nevertheless, how Se influences the metabolism of extracellular matrix (ECM) in cartilage remains unclear. The aim of the present study was to observe protein dimethylation by certain Se-sensitive PRMT and to elucidate its effects on the key transcriptional factor in cartilage. METHODS: We observed the expression of selenoproteins and markers of ECM metabolism in chondrocytes and articular cartilage of the rats under Se-deficiency by RT-qPCR, immunoblotting and immunohistochemistry. Then, we analyzed the expression of total dimethylated protein by using specific antibody under different Se statuses. After Se sensitive PRMT was identified, we used siRNA or PRMT inhibitor or stably overexpressing vector to intervene in the PRMT expression and identified the key transcriptional factor. Co-immunoprecipitation was applied to verify the interaction between PRMT and the key transcriptional factor. Finally, we measured the half-life time of the key transcriptional factor by immunoblotting after cycloheximide treatment. RESULTS: In chondrocytes and cartilage of the rats with Se deficiency, we found an aberrant metabolism manifesting decreased expression of Col2a1 and increased expression of Mmp-3. Then, we identified that PRMT5 was the unique type II PRMT, sensitive to Se status. PRMT5 upregulation led to the increased COL2A1 expression but decreased MMP-3 expression in chondrocytes. Furthermore, we revealed that PRMT5 improved SOX9 stability by dimethylating the protein, which contributed to maintain the matrix metabolic homeostasis of the chondrocytes. CONCLUSIONS: Se-sensitive PRMT5 increases the half-life of SOX9 protein via PTM and helps to maintain ECM homeostasis of the articular cartilage.
OBJECTIVES:Selenium (Se) plays pivotal roles in maintaining optimal health. Nevertheless, how Se influences the metabolism of extracellular matrix (ECM) in cartilage remains unclear. The aim of the present study was to observe protein dimethylation by certain Se-sensitive PRMT and to elucidate its effects on the key transcriptional factor in cartilage. METHODS: We observed the expression of selenoproteins and markers of ECM metabolism in chondrocytes and articular cartilage of the rats under Se-deficiency by RT-qPCR, immunoblotting and immunohistochemistry. Then, we analyzed the expression of total dimethylated protein by using specific antibody under different Se statuses. After Se sensitive PRMT was identified, we used siRNA or PRMT inhibitor or stably overexpressing vector to intervene in the PRMT expression and identified the key transcriptional factor. Co-immunoprecipitation was applied to verify the interaction between PRMT and the key transcriptional factor. Finally, we measured the half-life time of the key transcriptional factor by immunoblotting after cycloheximide treatment. RESULTS: In chondrocytes and cartilage of the rats with Se deficiency, we found an aberrant metabolism manifesting decreased expression of Col2a1 and increased expression of Mmp-3. Then, we identified that PRMT5 was the unique type II PRMT, sensitive to Se status. PRMT5 upregulation led to the increased COL2A1 expression but decreased MMP-3 expression in chondrocytes. Furthermore, we revealed that PRMT5 improved SOX9 stability by dimethylating the protein, which contributed to maintain the matrix metabolic homeostasis of the chondrocytes. CONCLUSIONS:Se-sensitive PRMT5 increases the half-life of SOX9 protein via PTM and helps to maintain ECM homeostasis of the articular cartilage.