Stimulation of differentiation in sodium-dependent vitamin C transporter 2 overexpressing MC3T3-E1 osteoblasts.
Sodium-dependent vitamin C transporter (SVCT) 2 facilitates reduced ascorbic acid (AA) transport in MC3T3-E1 osteoblasts. Our previous studies suggested that Zn-induced osteoblast differentiation and Ca2+-, PO4(3-)-stimulated osteopontin (OPN) expression might result from their up-regulation effect on SVCT2 expression and AA uptake. Here, we investigated the role of SVCT2 on osteoblast differentiation by using SVCT2-overexpressing cells. Two clones of SVCT2-introduced cells overexpressed SVCT2 mRNA by 2.8- and 3.1-fold those of control cells, which resulted in obvious increase of AA uptake by 2.1- and 2.4-fold in Vmax with no change in Km. Alkaline phosphatase activity, hydroxyproline content significantly increased in SVCT2-overexpressing cells, and the induction of OPN mRNA was through up-regulation of OPN promoter activity by SVCT2 overexpression. Moreover, SVCT2-overexpressing cells exhibited more ability to promote mineralization and increase calcium deposition under the stimulation of 5 mM beta-glycerophosphate. These findings indicate that SVCT2 stimulates osteoblast differentiation and mineralization.
Wu
Ximei
X
Department of Toxicology, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka 565-0871, Japan.
Itoh
Norio
N
Taniguchi
Takashi
T
Hirano
Junko
J
Nakanishi
Tsuyoshi
T
Tanaka
Keiichi
K
D016475:3T3 Cells; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism; D001692:Biological Transport; D002113:Calcification, Physiologic / Q000502:physiology; D002454:Cell Differentiation; D003094:Collagen / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006909:Hydroxyproline / Q000378:metabolism; D007700:Kinetics; D051379:Mice; D029363:Organic Anion Transporters, Sodium-Dependent / Q000096:biosynthesis / Q000502:physiology*; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism*; D053495:Osteopontin; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012795:Sialoglycoproteins / Q000096:biosynthesis / Q000235:genetics; D060347:Sodium-Coupled Vitamin C Transporters; D027981:Symporters / Q000096:biosynthesis / Q000502:physiology*
D029363:Organic Anion Transporters, Sodium-Dependent; D012333:RNA, Messenger; D011994:Recombinant Proteins; D012795:Sialoglycoproteins; C555165:Slc23a2 protein, mouse; D060347:Sodium-Coupled Vitamin C Transporters; C506896:Spp1 protein, mouse; D027981:Symporters; D053495:Osteopontin; D003094:Collagen; D000469:Alkaline Phosphatase; D001205:Ascorbic Acid; D006909:Hydroxyproline