title: Sirtuin 3 is required for osteogenic differentiation through maintenance of PGC-1ɑ-SOD2-mediated regulation of mitochondrial function.
abstract: Osteogenic differentiation is crucial for the maintenance of bone homeostasis. Sirtuin 3 (SIRT3), a member of sirtuins family, functions as a critical deacetylase that regulates many key proteins. In the current study, we aimed to clarify the role of SIRT3 in osteogenic differentiation and the possible mechanisms, using mouse pre-osteoblastic MC3T3-E1 cells. Expression of SIRT3 was substantially increased in differentiated MC3T3-E1 cells. Knock down of SIRT3 significantly decreased alkaline phosphatase (ALP) staining, and mRNA expression of runt-related transcription factor 2 (Runx2) and collagen type I ɑ 1 (Col1ɑ1), and osteocalcin in differentiated MC3T3-E1 cells. Overexpression of wild type but not mutant SIRT3 could reverse SIRT3 knockdown-resulted decrease of ALP staining. Complex I, II, III, IV, and V activities, oxygen consumption and mitochondrial membrane potential were significantly decreased by SIRT3 knockdown. Moreover, SIRT3 knockdown reduced mitochondrial density, increased mitochondrial size and decreased the expression of NRF1 and TFAM. Knock down of SIRT3 decreased mRNA and protein expression of SOD2 and increased ROS level. Overexpression of SOD2 significantly suppressed SIRT3 knockdown-induced decrease of mitochondrial function and osteogenic differentiation. SIRT3 knockdown resulted in a significant decrease of PGC-1ɑ protein expression but not mRNA expression. Overexpression of wild type but not mutant SIRT3 could reverse SIRT3 knockdown-resulted decrease of PGC-1ɑ protein expression. Moreover, we detected a direct interaction between SIRT3 and PGC-1ɑ and SIRT3 knockdown reduced SIRT3 and PGC-1ɑ interaction, resulting in a reduction of PGC-1ɑ protein stability and PGC-1ɑ-binding in the promoters of SOD2. Overexpression of PGC-1ɑ blocked SIRT3 knockdown-induced decrease of SOD2 expression, increase of ROS level, and decrease of mitochondrial function and biogenesis, leading to improvement of osteogenesis. Overall, the data provide a better understanding of the role of SIRT3 in osteogenic differentiation.
authors.affiliation: Department of Orthopedic, Tangdu Hospital, Fourth Military Medical University, #569 Xinsi Road, Xi'an 710038, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Ding
authors.affiliation: Department of Orthopedic, BaoJi Centre Hospital, #8 Jiangtan Road, Bao ji 721008, China.
authors.forename: Hongmei
authors.initials: H
authors.lastname: Yang
authors.affiliation: Department of Orthopedic, Tangdu Hospital, Fourth Military Medical University, #569 Xinsi Road, Xi'an 710038, China.
authors.forename: Yucai
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Orthopedic, Tangdu Hospital, Fourth Military Medical University, #569 Xinsi Road, Xi'an 710038, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Orthopedic, Tangdu Hospital, Fourth Military Medical University, #569 Xinsi Road, Xi'an 710038, China.
authors.forename: Zhenwei
authors.initials: Z
authors.lastname: Ji
authors.affiliation: Department of Orthopedic, Tangdu Hospital, Fourth Military Medical University, #569 Xinsi Road, Xi'an 710038, China.
authors.forename: Honghui
authors.initials: H
authors.lastname: Sun
mesh_terms: D000818:Animals; D002460:Cell Line; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008928:Mitochondria / Q000378:metabolism*; D010012:Osteogenesis / Q000235:genetics / Q000502:physiology*; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha / Q000235:genetics / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D056566:Sirtuin 3 / Q000235:genetics / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism*; D000099156:Superoxide Dismutase 2
chemical_list: D050659:Core Binding Factor Alpha 1 Subunit; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D017382:Reactive Oxygen Species; D056566:Sirtuin 3; D013482:Superoxide Dismutase; D000099156:Superoxide Dismutase 2; C485290:Ppargc1a protein, mouse
keywords: mitochondrial function; osteogenic differentiation; peroxisome proliferator-activated receptor-γ co-activator-1ɑ; sirtuin 3; superoxide dismutase 2