Bone morphogenetic protein 2 and dexamethasone synergistically increase alkaline phosphatase levels through JAK/STAT signaling in C3H10T1/2 cells.
Alkaline phosphatase (ALP) is generally believed to be a faithful marker of osteoblast differentiation, and its expression is induced by bone morphogenetic protein-2 (BMP-2) and dexamethasone (Dex). However, the effects of combined administration of BMP-2 and Dex on ALP transcription have not been extensively examined. In this study, we found that BMP-2 and Dex synergistically increase ALP levels in mouse C3H10T1/2 pluripotent stem cells. However, switching from one inducer to the other, by adding BMP-2 or Dex to cell cultures at different times, was no more effective than continuous treatment with either inducer alone. A significant induction of ALP mRNA expression was observed only in cells continuously treated with both inducers. This result suggests that both BMP-2 and Dex may act in the same pathway or at the same stage of differentiation. A luciferase assay using ALP promoter deletion constructs showed that a region of the promoter containing a putative signal transducer and activator of transcription 3 (STAT3) response element (SRE) responds to treatment with a combination of BMP-2 and Dex. Furthermore, a ChIP assay indicated that STAT3 bound to the SRE. In addition, a STAT3 siRNA suppressed the synergistic effect of BMP-2 and Dex on ALP levels. These results indicate that STAT3 may play an important role in regulating ALP expression. To our knowledge, this is the first time that STAT3 has been implicated in the regulation of ALP expression by BMP-2 and Dex. These findings raise the possibility of developing new strategies for the enhancement of bone formation using a combination of BMPs and Dex.
Mikami
Yoshikazu
Y
1st Department of Anatomy, Nihon University School of Dentistry, Chiyoda-ku, Tokyo, Japan. mikami-t@dent.nihon-u.ac.jp
Asano
Masatake
M
Honda
Masaki J
MJ
Takagi
Minoru
M
D000469:Alkaline Phosphatase / Q000096:biosynthesis* / Q000235:genetics; D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000378:metabolism*; D002460:Cell Line; D003907:Dexamethasone / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction; D005938:Glucocorticoids / Q000494:pharmacology*; D006801:Humans; D053612:Janus Kinases / Q000378:metabolism*; D051379:Mice; D010006:Osteoblasts / Q000187:drug effects* / Q000201:enzymology; D010012:Osteogenesis / Q000187:drug effects; D039904:Pluripotent Stem Cells / Q000187:drug effects* / Q000201:enzymology; D011401:Promoter Regions, Genetic / Q000187:drug effects; D012333:RNA, Messenger / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D055411:TGF-beta Superfamily Proteins / Q000378:metabolism; D013997:Time Factors; D015533:Transcriptional Activation / Q000187:drug effects; D014162:Transfection
C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D005938:Glucocorticoids; D012333:RNA, Messenger; D011994:Recombinant Proteins; D050796:STAT3 Transcription Factor; C494087:Stat3 protein, mouse; D055411:TGF-beta Superfamily Proteins; D003907:Dexamethasone; D053612:Janus Kinases; D000469:Alkaline Phosphatase