title: A molecular mechanism of pyruvate protection against cytotoxicity of reactive oxygen species in osteoblasts.
abstract: We demonstrated previously that exogenous pyruvate has a protective action against cell death by hydrogen peroxide in cultured osteoblasts through a mechanism associated with its antioxidative property. In the present study, we have evaluated possible participation of monocarboxylate transporters (MCTs) responsible for the bidirectional membrane transport of pyruvate in the cytoprotective property in osteoblasts. Expression of the MCT2 isoform was found in cultured rat calvarial osteoblasts and in osteoblasts located on mouse tibia at both mRNA and protein levels. The accumulation of [14C]pyruvate occurred in a temperature- and pH-dependent manner in osteoblasts cultured for 7 days with high sensitivity to a specific MCT inhibitor, whereas pyruvate was released into extracellular spaces from cultured osteoblasts in a fashion sensitive to the MCT inhibitor. Transient overexpression of the MCT2 isoform led to reduced vulnerability to the cytotoxicity of hydrogen peroxide with an increased activity of [14C]pyruvate accumulation in murine osteoblastic MC3T3-E1 cells. Ovariectomy significantly decreased the content of pyruvate in femoral bone marrows in mice in vivo, whereas daily i.p. administration of pyruvate at 0.25 g/kg significantly prevented alterations of several histomorphometric parameters as well as cancellous bone loss in femurs by ovariectomy on 28 days after the operation. These results suggest that MCTs may be functionally expressed by osteoblasts to play a pivotal role in mechanisms related to the cytoprotective property of pyruvate.
authors.affiliation: Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School of Natural Science and Technology, Kanazawa, Ishikawa 920-1192, Japan.
authors.forename: Eiichi
authors.initials: E
authors.lastname: Hinoi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Takarada
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Tsuchihashi
authors.forename: Sayumi
authors.initials: S
authors.lastname: Fujimori
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Moriguchi
authors.forename: Liyang
authors.initials: L
authors.lastname: Wang
authors.forename: Kyosuke
authors.initials: K
authors.lastname: Uno
authors.forename: Yukio
authors.initials: Y
authors.lastname: Yoneda
mesh_terms: D000818:Animals; D001862:Bone Resorption; D002250:Carbon Radioisotopes; D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects; D017077:Culture Media, Conditioned; D005260:Female; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000378:metabolism* / Q000494:pharmacology; D051379:Mice; D008954:Models, Biological; D027501:Monocarboxylic Acid Transporters / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D010052:Ovariectomy; D011773:Pyruvates / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D024483:Vitamin K 3 / Q000494:pharmacology
chemical_list: D002250:Carbon Radioisotopes; D017077:Culture Media, Conditioned; D027501:Monocarboxylic Acid Transporters; D011773:Pyruvates; D012333:RNA, Messenger; C490426:Slc16a7 protein, mouse; D024483:Vitamin K 3; D006861:Hydrogen Peroxide