title: Impaired glycolytic metabolism causes chondrocyte hypertrophy-like changes via promotion of phospho-Smad1/5/8 translocation into nucleus.
abstract: OBJECTIVE
  Hypertrophy-like changes are often observed in chondrocytes during the development of osteoarthritis (OA). These changes play a crucial part in the OA-associated cartilage degradation and osteophyte formation. However, the pathogenesis leading to such changes is still unknown. In this study, we investigated the mechanism by which these hypertrophy-like changes are induced from the viewpoint of impaired glycolytic metabolism.
  
  
  METHODS
  The effect of sodium fluoride (NaF) on glycolytic metabolism of cultured chondrocytes was confirmed by measurement of intracellular adenosine triphosphate (ATP) production. Translocation of phosphorylated Smad1/5/8 to the nucleus was evaluated by subcellular fractionation and Western blotting. Chondrocyte hypertrophy-like changes were investigated by real-time RT-PCR and Western blot analysis of differentiation markers.
  
  
  RESULTS
  ATP production was dose-dependently decreased by NaF in the human chondrocytic cell line HCS-2/8. In addition, both chondrocyte proliferation and differentiation were inhibited, whereas cell death was promoted by treatment with NaF. Interestingly, combinational treatment with NaF and lactate enhanced translocation of phospho-Smad1/5/8 to the nucleus, as well as gene expression of ALP, VEGF, COL10a1, and matrix metalloproteinase13 (MMP13), which were the markers of late mature and hypertrophic chondrocytes. Furthermore, the production of type X collagen and activation of MMP9 were also promoted under the same conditions.
  
  
  CONCLUSIONS
  These findings suggest that decreased ATP production by NaF promotes hypertrophy-like changes via activation of phospho-Smad1/5/8 in the presence of lactate. Novel metabolic aspects of OA pathogenesis are indicated herein.
authors: Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan. tnishida@md.okayama-u.ac.jp
authors: T
authors: T
authors: Nishida
authors: S
authors: S
authors: Kubota
authors: E
authors: E
authors: Aoyama
authors: M
authors: M
authors: Takigawa
mesh_terms: D000255:Adenosine Triphosphate / Q000096:biosynthesis; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D002467:Cell Nucleus / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D006019:Glycolysis / Q000187:drug effects / Q000502:physiology; D006801:Humans; D006984:Hypertrophy / Q000139:chemically induced / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D051896:Smad Proteins, Receptor-Regulated / Q000378:metabolism*; D051898:Smad1 Protein / Q000378:metabolism; D051902:Smad5 Protein / Q000378:metabolism; D051904:Smad8 Protein / Q000378:metabolism; D012969:Sodium Fluoride / Q000008:administration & dosage / Q000494:pharmacology; D019354:Sodium Lactate / Q000494:pharmacology
chemical_list: D019485:Bone Morphogenetic Proteins; D004338:Drug Combinations; D016328:NF-kappa B; C497399:SMAD1 protein, human; C497797:SMAD5 protein, human; C107514:SMAD9 protein, human; D051896:Smad Proteins, Receptor-Regulated; D051898:Smad1 Protein; D051902:Smad5 Protein; D051904:Smad8 Protein; D000255:Adenosine Triphosphate; D012969:Sodium Fluoride; D019354:Sodium Lactate