title: Parathyroid hormone regulates osteoblast differentiation in a Wnt/β-catenin-dependent manner.
abstract: Intermittent parathyroid hormone (PTH) administration shows an anabolic effect on bone. However, the mechanisms are not fully studied. Recent studies suggest that Wnt signaling is involved in PTH-induced bone formation. The current study was to examine if Wnt/β-catenin pathway is required during PTH-induced osteoblast differentiation. Osteoblastic MC3T3-E1 cells were treated with human PTH (1-34) (hPTH [1-34]) and expression levels of osteoblast differentiation markers were detected by real-time PCR. RNA levels of β-catenin, Runx2, Osteocalcin, Alkaline phosphatase, and Bone sialoprotein were significantly up-regulated after treatment with 10(-8) M of hPTH (1-34) for 6 h. Alkaline phosphatase activity and protein expression of β-catenin were also increased after 6 days of intermittent treatment with hPTH (1-34) in MC3T3-E1 cells. hPTH (1-34) significantly enhanced Topflash Luciferase activity after 6 h of treatment. More important, PTH-induced Alkaline phosphatase activity was significantly inhibited by knocking down β-catenin expression in cells using siRNA. Real-time RT-PCR results further showed down regulation of Runx2, Osteocalcin, Alkaline phosphatase, Bone sialoprotein gene expression in β-catenin siRNA transfected cells with/without PTH treatment. These results clearly indicate that PTH stimulates Wnt/β-catenin pathway in MC3T3-E1 cells and osteoblast differentiation markers expression was up-regulated by activation of Wnt/β-catenin signaling. Our study demonstrated that PTH-induced osteoblast differentiation mainly through activation of Wnt/β-catenin pathway in osteoblastic MC3T3-E1 cells.
authors.affiliation: Department of Orthopaedics, Shengjing Hospital of China Medical University, Sanhao Street 36, Heping District, Shenyang 110004, China. tianyecmu2h@sina.com
authors.forename: Ye
authors.initials: Y
authors.lastname: Tian
authors.forename: Ying
authors.initials: Y
authors.lastname: Xu
authors.forename: Qin
authors.initials: Q
authors.lastname: Fu
authors.forename: Ming
authors.initials: M
authors.lastname: He
mesh_terms: D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism; D000818:Animals; D000943:Antigens, Differentiation / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects*; D015870:Gene Expression / Q000187:drug effects; D017930:Genes, Reporter; D006801:Humans; D049410:Luciferases, Renilla / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D010006:Osteoblasts / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D034622:RNA Interference; D019379:Teriparatide / Q000494:pharmacology*; D051153:Wnt Proteins / Q000378:metabolism*; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*
chemical_list: D000943:Antigens, Differentiation; D051153:Wnt Proteins; D051176:beta Catenin; D019379:Teriparatide; D049410:Luciferases, Renilla; D000469:Alkaline Phosphatase