Inductive effects of dexamethasone on the mineralization and the osteoblastic gene expressions in mature osteoblast-like ROS17/2.8 cells.
We examined the effects of dexamethasone (Dex), a synthetic glucocorticoid, on the formation of mineralized bone nodules and the gene expressions of the late osteoblastic markers, bone sialoprotein (BSP), osteocalcin (OC), and osteopontin (OPN) in mature osteoblast ROS17/2.8 cells. Treatment of ROS17/2.8 cells with Dex resulted in the induction of mineralization accompanied with increasing BSP and OC expressions. Previous reports have demonstrated that BSP and OC expressions are regulated by Runx2. Then, we hypothesized that Dex might promote osteoblastic differentiation and mineralization on ROS17/2.8 by Runx2. In this study, no effect was observed in mRNA and protein expression of Runx2. However, the transcriptional activity of Runx2 was enhanced by Dex treatment. Furthermore, the Dex-induced BSP and OC expressions decreased after the transfection of Runx2 small-interfering RNAs (siRNAs). These results suggested that the enhancement of Runx2 transcriptional activity by Dex treatment may be followed by the activation of osteoblast marker genes, such as BSP and OC to thereby produce a bone-specific matrix that subsequently becomes mineralized.
Mikami
Yoshikazu
Y
Department of Anatomy, Division of Functional Morphology, Dental Research Center, Nihon University School of Dentistry, 1-8-13 Kanda-surugadai, Chiyoda-ku, Tokyo 101-8310, Japan. mikami-t@dent.nihon-u.ac.jp
Omoteyama
Kazuki
K
Kato
Shigeyuki
S
Takagi
Minoru
M
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D000880:Anthraquinones / Q000737:chemistry; D015153:Blotting, Western; D002113:Calcification, Physiologic / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression / Q000187:drug effects*; D005938:Glucocorticoids / Q000494:pharmacology; D006651:Histocytochemistry; D058574:Integrin-Binding Sialoprotein; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism; D015675:Osteocalcin / Q000235:genetics / Q000378:metabolism; D053495:Osteopontin / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012795:Sialoglycoproteins / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D014162:Transfection
D000880:Anthraquinones; D050659:Core Binding Factor Alpha 1 Subunit; D005938:Glucocorticoids; D058574:Integrin-Binding Sialoprotein; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D012795:Sialoglycoproteins; D015675:Osteocalcin; D053495:Osteopontin; C004468:Alizarin Red S; D003907:Dexamethasone; D000469:Alkaline Phosphatase; D002118:Calcium