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  • Kaneko, Kazuo  (3)
  • Kobayashi, Keiji  (3)
  • 1
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 5, No. 1 ( 2015-06-25)
    Abstract: Mechanical stress and aging are major risk factors of cartilage degeneration. Human studies have previously reported that oxidative damage increased, while SOD2 protein was reciprocally downregulated in osteoarthritic degenerated cartilage. However, it remains unclear whether mitochondrial superoxide imbalance in chondrocytes causes cartilage degeneration. We herein demonstrate that mechanical loading promoted mitochondrial superoxide generation and selective Sod2 downregulation in chondrocytes in vivo and that mitochondrial superoxide inducer also downregulated Sod2 expression in chondrocytes in vitro . A genetically manipulated model revealed that Sod2 deficiency in chondrocytes also resulted in mitochondrial superoxide overproduction and dysfunction, thus leading to cartilage degeneration. Intra-articular injection of a permeable antioxidant effectively suppressed the mechanical loading-induced mitochondrial superoxide generation and cartilage degeneration in mice. Our findings demonstrate that mitochondrial superoxide plays a pivotal role in the development and progression of osteoarthritis and the mitochondrial superoxide balance may therefore be a promising target for the treatment of cartilage degeneration.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2015
    detail.hit.zdb_id: 2615211-3
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  • 2
    In: Journal of Bone and Mineral Research, Wiley, Vol. 28, No. 11 ( 2013-11), p. 2368-2380
    Abstract: Oxidative stress contributes to the pathogenesis of age‐related diseases as well as bone fragility. Our previous study demonstrated that copper/zinc superoxide dismutase ( Sod1 )‐deficient mice exhibit the induction of intracellular reactive oxygen species (ROS) and bone fragility resulting from low‐turnover bone loss and impaired collagen cross‐linking (Nojiri et al. J Bone Miner Res. 2011;26:2682–94). Mechanical stress also plays an important role in the maintenance of homeostasis in bone tissue. However, the molecular links between oxidative and mechanical stresses in bone tissue have not been fully elucidated. We herein report that mechanical unloading significantly increased intracellular ROS production and the specific upregulation of Sod1 in bone tissue in a tail‐suspension experiment. We also reveal that Sod1 loss exacerbated bone loss via reduced osteoblastic abilities during mechanical unloading. Interestingly, we found that the administration of an antioxidant, vitamin C, significantly attenuated bone loss during unloading. These results indicate that mechanical unloading, in part, regulates bone mass via intracellular ROS generation and the Sod1 expression, suggesting that activating Sod1 may be a preventive strategy for ameliorating mechanical unloading–induced bone loss. © 2013 American Society for Bone and Mineral Research.
    Type of Medium: Online Resource
    ISSN: 0884-0431 , 1523-4681
    URL: Issue
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    Language: English
    Publisher: Wiley
    Publication Date: 2013
    detail.hit.zdb_id: 2008867-X
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  • 3
    In: Scientific Reports, Springer Science and Business Media LLC, Vol. 5, No. 1 ( 2015-03-16)
    Abstract: Osteocytes are major bone cells that play a crucial role in maintaining the quality of and healing damage to bone tissue. The number of living osteocytes and canalicular networks declines in an age-dependent manner. However, the pathological effects of mitochondrial redox imbalances on osteocytes and bone metabolism have not been fully elucidated. We generated mice lacking mitochondrial superoxide dismutase 2 ( Sod2 ) in osteocytes. Like an aged bone, Sod2 depletion in the osteocytes positively enhanced the production of cellular superoxide in vivo . A bone morphological analysis demonstrated that the Sod2 -deficient femurs showed remarkable bone loss in an age-dependent manner. Interestingly, Sod2 loss induced markedly disorganized osteocytic canalicular networks and decreased the number of live osteocytes. Furthermore, Sod2 deficiency significantly suppressed bone formation and increased bone resorption concomitant with the upregulation of sclerostin and receptor activator of NF-κB ligand (RANKL). In vitro experiments also revealed that treatment with paraquat, a superoxide inducer in mitochondria, promoted the RANKL expression via, in part, ERK phosphorylation. These findings demonstrate that the mitochondrial superoxide induced in osteocytes by Sod2 ablation causes age-related bone loss due to the impairment of canalicular networks and bone metabolism via the deregulation of the sclerostin and RANKL expression.
    Type of Medium: Online Resource
    ISSN: 2045-2322
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2015
    detail.hit.zdb_id: 2615211-3
    Location Call Number Limitation Availability
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