title: Crosstalk between Smad2/3 and specific isoforms of ERK in TGF-β1-induced TIMP-3 expression in rat chondrocytes.
abstract: This study investigated the roles of ERK1 and ERK2 in transforming growth factor-β1 (TGF-β1)-induced tissue inhibitor of metalloproteinases-3 (TIMP-3) expression in rat chondrocytes, and the specific roles of ERK1 and ERK2 in crosstalk with Smad2/3 were investigated to demonstrate the molecular mechanism of ERK1/2 regulation of TGF-β1 signalling. To examine the interaction of specific isoforms of ERK and the Smad2/3 signalling pathway, chondrocytes were infected with LV expressing either ERK1 or ERK2 siRNA and stimulated with or without TGF-β1. At indicated time-points, TIMP-3 expression was determined by real-time PCR and Western blotting; p-Smad3, nuclear p-Smad3, Smad2/3, p-ERK1/2 and ERK1/2 levels were assessed. And then, aggrecan, type II collagen and the intensity of matrix were examined. TGF-β1-induced TIMP-3 expression was significantly inhibited by ERK1 knock-down, and the decrease in TIMP-3 expression was accompanied by a reduction of p-Smad3 in ERK1 knock-down cells. Knock-down of ERK2 had no effect on neither TGF-β1-induced TIMP-3 expression nor the quantity of p-Smad3. Moreover, aggrecan, type II collagen expression and the intensity of matrix were significantly suppressed by ERK1 knock-down instead of ERK2 knock-down. Taken together, ERK1 and ERK2 have different roles in TGF-β1-induced TIMP-3 expression in rat chondrocytes. ERK1 instead of ERK2 can regulate TGF-β/Smad signalling, which may be the mechanism through which ERK1 regulates TGF-β1-induced TIMP-3 expression.
authors.affiliation: Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China.
authors.forename: Yanhui
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Gu
authors.affiliation: Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China.
authors.forename: Tong
authors.initials: T
authors.lastname: Zhu
authors.affiliation: Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Jin
authors.affiliation: Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China.
authors.forename: Xiaopeng
authors.initials: X
authors.lastname: Hu
authors.affiliation: Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Wang
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D019902:Chondrocytes / Q000187:drug effects / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D007527:Isoenzymes / Q000378:metabolism; D016086:Lentivirus / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D051899:Smad2 Protein / Q000378:metabolism*; D051900:Smad3 Protein / Q000378:metabolism*; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*
chemical_list: D007527:Isoenzymes; D034741:RNA, Small Interfering; D051899:Smad2 Protein; D051900:Smad3 Protein; D019717:Tissue Inhibitor of Metalloproteinase-3; D053773:Transforming Growth Factor beta1; D048049:Extracellular Signal-Regulated MAP Kinases
keywords: Crosstalk; ERK isoforms; Osteoarthritis; Smad2/3; TGF-β1; TIMP3