Osteoblast protects osteoclast devoid of sodium-dependent vitamin C transporters from oxidative cytotoxicity of ascorbic acid.
The view that ascorbic acid indirectly benefits osteoclastogenesis through expression of receptor activator of nuclear factor-kappaB (NF-kappaB) ligand (RANKL) by osteoblasts is prevailing. In this study, we have examined the direct effect of ascorbic acid on osteoclastogenesis in cultured mouse osteoclasts differentiated from bone marrow precursors. The absence of alkaline phosphatase and osteoblastic marker genes validated the usefulness of isolation procedures. Sustained exposure to ascorbic acid, but not to dehydroascorbic acid, significantly reduced the number of multinucleated cells positive to tartrate-resistant acid phosphatase (TRAP) staining. In cultured osteoclasts, mRNA expression was seen for glucose transporter-1 involved in membrane transport of dehydroascorbic acid, but not for sodium-dependent vitamin C transporters-1 and -2 that are both responsible for the transport of ascorbic acid. The inhibition by ascorbic acid was completely prevented by catalase, while ascorbic acid or hydrogen peroxide drastically increased the number of cells stained with propidium iodide and the generation of reactive oxygen species, in addition to inducing mitochondrial membrane depolarization in cultured osteoclasts. In pre-osteoclastic cell line RAW264.7 cells, ascorbic acid similarly inhibited the formation of TRAP-positive multinucleated cells, with a significant decrease in RANKL-induced NF-kappaB transactivation. Moreover, co-culture with osteoblastic MC3T3-E1 cells significantly prevented the ascorbic acid-induced decrease in the number of TRAP-positive multinucleated cells in RAW264.7 cells. These results suggest that ascorbic acid may play a dual repulsive role in osteoclastogenesis toward bone remodeling through the direct cytotoxicity mediated by oxidative stress to osteoclasts, in addition to the indirect trophism mediated by RANKL from osteoblasts.
Takarada
Takeshi
T
Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School of Natural Science and Technology, Kanazawa, Ishikawa, Japan.
Hinoi
Eiichi
E
Kambe
Yuki
Y
Sahara
Koichi
K
Kurokawa
Shintaro
S
Takahata
Yoshifumi
Y
Yoneda
Yukio
Y
D019297:2,4-Dinitrophenol / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001205:Ascorbic Acid / Q000378:metabolism* / Q000633:toxicity; D001483:Base Sequence; D016723:Bone Remodeling / Q000502:physiology; D002374:Catalase / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D051379:Mice; D029363:Organic Anion Transporters, Sodium-Dependent / Q000378:metabolism*; D010006:Osteoblasts / Q000201:enzymology / Q000378:metabolism / Q000502:physiology*; D010010:Osteoclasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects* / Q000502:physiology; D053245:RANK Ligand / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D060347:Sodium-Coupled Vitamin C Transporters; D027981:Symporters / Q000378:metabolism*; D013997:Time Factors
D000975:Antioxidants; D004791:Enzyme Inhibitors; D029363:Organic Anion Transporters, Sodium-Dependent; D053245:RANK Ligand; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D060347:Sodium-Coupled Vitamin C Transporters; D027981:Symporters; D006861:Hydrogen Peroxide; D002374:Catalase; D001205:Ascorbic Acid; D019297:2,4-Dinitrophenol