title: SGTB Promotes the Caspase-Dependent Apoptosis in Chondrocytes of Osteoarthritis.
abstract: The purpose of this study is to investigate the expression of small glutamine-rich tetratricopeptide repeat (TPR)-containing β (SGTB) in articular cartilage of osteoarthritis (OA) and analyze the relationship between SGTB and chondrocyte apoptosis. We established an OA rat model by the meniscal/ligamentous injury (MLI) modeling method and observed the expression of SGTB in articular cartilage by immunohistochemistry and RT-PCR. Human SW1353 chondrosarcoma cells were treated with interleukin-1β (IL-1β) to mimic the OA-like chondrocyte injury in vitro, and Western blot was employed to examine the IL-1β-induced expression of SGTB and active caspase-3. The co-localization of SGTB and active caspase-3 was confirmed by immunofluorescence. We knocked down SGTB expression by RNA interference (RNAi) and overexpressed SGTB by plasmid transfection. Western blot was carried out to detect the knockdown/overexpressing efficiency of SGTB and evaluate its effects on IL-1β-stimulated expression of active caspase-3 in SW1353 cells. Annexin V/propidium iodide staining was used to detect chondrocyte apoptosis. Then, Western blot was carried out to examine the IL-1β-induced expression of Hsp70 and evaluate SGTB effects on IL-1β-stimulated expression of Hsp70 in SW1353 cells. SGTB expression was significantly up-regulated in articular cartilage of OA rat model. IL-1β stimulation increased the expression of SGTB and active caspase-3 in SW1353 cells. SGTB co-localized with active caspase-3 in IL-1β-treated SW1353 cells. SGTB inhibition significantly reduced IL-1β-stimulated expression of active caspase-3 in SW1353 cells. In line with this, overexpressing SGTB via Myc-SGTB transfection increased the active caspase-3 level in IL-1β-stimulated SW1353 cells. Moreover, flow cytometry assay demonstrated that SGTB knockdown alleviated IL-1β-induced apoptosis, but it was increased in SW1353 cells that overexpressed SGTB. Overexpressing SGTB via Myc-SGTB transfection decreased the Hsp70 level in IL-1β-stimulated SW1353 cells. Our results suggested that SGTB positively regulate the activation of caspase-3 by negatively regulating the activity of Hsp70 and might promote chondrocyte apoptosis in OA. This study may provide a novel insight into the pathophysiology of OA and a potential therapeutic target for its treatment.
authors.affiliation: Department of Orthopedic Surgery, the First Affiliated Hospital of Soochow University, Suzhou, 215006, China.|Department of Spine Surgery, the Second Affiliated Hospital of Nantong University, Nantong, 226001, China.
authors.forename: Guofeng
authors.initials: G
authors.lastname: Bao
authors.affiliation: Department of Orthopaedics, Affiliated Hospital of Nantong University, Nantong University, Nantong, 226001, China.
authors.forename: Libin
authors.initials: L
authors.lastname: Xu
authors.affiliation: Department of Orthopaedics, Affiliated Hospital of Nantong University, Nantong University, Nantong, 226001, China.
authors.forename: Xinbao
authors.initials: X
authors.lastname: Xu
authors.affiliation: Department of Orthopaedics, Affiliated Hospital of Nantong University, Nantong University, Nantong, 226001, China.
authors.forename: Leilei
authors.initials: L
authors.lastname: Zhai
authors.affiliation: Department of Orthopaedics, Affiliated Hospital of Nantong University, Nantong University, Nantong, 226001, China.
authors.forename: Chengwei
authors.initials: C
authors.lastname: Duan
authors.affiliation: Department of Spine Surgery, the Second Affiliated Hospital of Nantong University, Nantong, 226001, China.
authors.forename: Dawei
authors.initials: D
authors.lastname: Xu
authors.affiliation: Department of Spine Surgery, the Second Affiliated Hospital of Nantong University, Nantong, 226001, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Song
authors.affiliation: Department of Orthopaedics, Affiliated Hospital of Nantong University, Nantong University, Nantong, 226001, China.
authors.forename: Zhongbing
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Department of Orthopaedics, Affiliated Hospital of Nantong University, Nantong University, Nantong, 226001, China.
authors.forename: Ran
authors.initials: R
authors.lastname: Tao
authors.affiliation: Department of Spine Surgery, the Second Affiliated Hospital of Nantong University, Nantong, 226001, China.
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Cui
authors.affiliation: Department of Orthopedic Surgery, the First Affiliated Hospital of Soochow University, Suzhou, 215006, China. Yanghuilin_suzhou@aliyun.com.
authors.forename: Huilin
authors.initials: H
authors.lastname: Yang
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002358:Cartilage, Articular / Q000166:cytology / Q000473:pathology*; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism*; D004195:Disease Models, Animal; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis; D006801:Humans; D053583:Interleukin-1beta / Q000494:pharmacology*; D008297:Male; D018832:Molecular Chaperones; D010003:Osteoarthritis / Q000188:drug therapy / Q000473:pathology*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D015854:Up-Regulation
chemical_list: D002352:Carrier Proteins; D018840:HSP70 Heat-Shock Proteins; C508585:IL1B protein, human; D053583:Interleukin-1beta; D018832:Molecular Chaperones; D034741:RNA, Small Interfering; C512694:Sgta protein, rat; D053148:Caspase 3
keywords: SGTB; apoptosis; interleukin-1β; osteoarthritis