title: GPx1 knockdown suppresses chondrogenic differentiation of ATDC5 cells through induction of reductive stress.
abstract: Glutathione peroxidase 1 (GPx1) is a selenium (Se)-containing protein and is induced in cartilage formation. GPx1 eliminates reactive oxygen species (ROS), which are required for chondrogenic induction. The physiological properties of GPx1 in cartilage and the redox mechanisms involved are not known. The effects of GPx1 on chondrogenic differentiation of ATDC5 cells were examined through short hairpin RNA-mediated gene silencing. The results demonstrated that GPx1 knockdown impaired gene expression of sex determining region Y-box 9, collagen II (Col II), and aggrecan. GPx1 knockdown suppressed the accumulation of cartilage glycosaminoglycans (GAGs) and the proliferation of chondrocyte. GPx1 knockdown also induced cell apoptosis. However, cell sensitivity toward exogenous oxidative stress was not increased after GPx1 knockdown. Unexpectedly, GPx1 knockdown not only induced oxidative stress characterized by the increased production of ROS but also caused reductive stress indicated by an elevation of glutathione (GSH)/oxidized GSH (GSSG) ratio. Furthermore, GPx1 knockdown-mediated reductive and oxidative stress could be antagonized by a thiol-oxidizing agent diamide and a thiol-containing compound N-acetylcysteine (NAC), respectively. Moreover, NAC attenuated GPx1 knockdown-induced cell apoptosis, while diamide prevented GPx1 knockdown-suppressed chondrocyte proliferation. Finally, diamide but not NAC could rescue GPx1 knockdown-mediated impaired chondrogenic differentiation. In summary, GPx1 is essential for chondrogenic induction in ATDC5 cells mainly through modulation of intracellular GSH/GSSG ratio, rather than an antioxidant enzyme to detoxify ROS. In addition, GPx1 knockdown-induced impaired chondrogenesis may participate in the pathogenesis of the endemic osteoarthropathy due to Se deficiency. These observations offer novel insights for the development of therapeutic target during cartilage degeneration.
authors.affiliation: Department of Human Anatomy, Histology and Embryology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China.
authors.forename: Jidong
authors.initials: J
authors.lastname: Yan
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China.
authors.forename: Yuanxu
authors.initials: Y
authors.lastname: Guo
authors.affiliation: College of Life Sciences, Northwest University, Xi'an 710069, China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Fei
authors.affiliation: Xi'an Hong Hui Hospital, The Affiliated Hospital of Xi'an Jiaotong University School of Medicine, Xi'an 710054, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Zhang
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Han
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an 710061, China.|Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an 710061, China.
authors.forename: Shemin
authors.initials: S
authors.lastname: Lu
mesh_terms: D053674:Aggrecans / Q000235:genetics / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000235:genetics; D015153:Blotting, Western; D002454:Cell Differentiation / Q000235:genetics*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000235:genetics; D019902:Chondrocytes / Q000378:metabolism*; D020219:Chondrogenesis / Q000235:genetics; D024043:Collagen Type II / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D005978:Glutathione / Q000378:metabolism; D019803:Glutathione Disulfide / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D018384:Oxidative Stress; D034622:RNA Interference; D017382:Reactive Oxygen Species / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D055758:SOX9 Transcription Factor / Q000235:genetics / Q000378:metabolism; D000094765:Glutathione Peroxidase GPX1
chemical_list: D053674:Aggrecans; D024043:Collagen Type II; D017382:Reactive Oxygen Species; D055758:SOX9 Transcription Factor; C527933:Sox9 protein, mouse; D005979:Glutathione Peroxidase; D005978:Glutathione; D019803:Glutathione Disulfide; D000094765:Glutathione Peroxidase GPX1; C000722068:Gpx1 protein, mouse
keywords: chondrocyte differentiation; glutathione peroxidase 1; oxidative stress; reactive oxygen species; reductive stress