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Integration of phosphatidylinositol 3-kinase, Akt kinase, and Smad signaling pathway in BMP-2-induced osterix expression.

ABSTRACT: Osterix (Osx), a BMP-2-regulated transcription factor, controls expression of genes essential for osteoblast differentiation. Using progressive deletion of the Osx promoter, we characterized a Smad binding element (SBE) between -552 and -839 bp from its transcription start site. Electrophoretic mobility shift assay and chromatin immunoprecipitation assay showed binding and in vivo recruitment of Smads 1 and 5 to the Osx SBE. Inactivation of PI 3-kinase by the pharmacologic inhibitor Ly294002 or by dominant negative (DN) enzyme significantly blocked BMP-2-induced Osx protein and mRNA expression and Osx transcription. Finally, both DN PI 3-kinase and DN Akt significantly attenuated Smad 5-dependent transcription of Osx, demonstrating the first evidence for a concerted action of PI 3-kinase/Akt signaling with BMP-specific Smads for expression of Osx.

SUBMITTER: Mandal CC

PROVIDER: S-EPMC3055166 | biostudies-literature | 2010 Dec

REPOSITORIES: biostudies-literature

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Integration of phosphatidylinositol 3-kinase, Akt kinase, and Smad signaling pathway in BMP-2-induced osterix expression.

Mandal Chandi Charan CC Drissi Hicham H Choudhury Goutam Ghosh GG Ghosh-Choudhury Nandini N

Calcified tissue international 20100926 6

Osterix (Osx), a BMP-2-regulated transcription factor, controls expression of genes essential for osteoblast differentiation. Using progressive deletion of the Osx promoter, we characterized a Smad binding element (SBE) between -552 and -839 bp from its transcription start site. Electrophoretic mobility shift assay and chromatin immunoprecipitation assay showed binding and in vivo recruitment of Smads 1 and 5 to the Osx SBE. Inactivation of PI 3-kinase by the pharmacologic inhibitor Ly294002 or ...[more]

PMID: 20872216

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Project description:Bone defects are a global public health problem. However, the available methods for bone regeneration are limited. In recent years, the application of traditional Chinese herbs for bone regeneration has attracted increasing attention. β-ecdysterone is a herbal extract similar to estrogen that promotes the metabolism of cell protein synthesis; however, its function on bone regeneration is not yet clear. In this study, we investigated the function of β-ecdysterone on osteoblast differentiation and bone regeneration in vitro and in vivo. MC3T3-E1 cells were used to test the function of β-ecdysterone on osteoblast differentiation and bone regeneration in vitro. The results of the CCK-8 assay suggested that the proliferation of MC3T3-E1 cells was promoted by β-ecdysterone. Furthermore, β-ecdysterone influenced the expression of osteogenesis-related genes, and the bone regeneration capacity of MC3T3-E1 cells was detected by PCR, the alkaline phosphatase (ALP) test, and the Alizarin Red test. β-ecdysterone could up-regulate the expression of osteoblastic-related genes, and promoted ALP activity and the formation of calcium nodules. Moreover, we also determined that β-ecdysterone increased the mRNA and protein levels of components of the BMP-2/Smad/Runx2/Osterix pathway. DNA sequencing further confirmed these target effects. β-ecdysterone promoted bone formation by enhancing gene expression of the BMP-2/Smad/Runx2/Osterix signaling pathway and by the enrichment biological processes. For in vivo experiments, the femur condyle defection model was constructed by drilling a critical-sized (3×3 mm) defect in 12-week-old SD male rats to further assess the bone regeneration functions of β-ecdysterone. The results of micro-CT showed that β-ecdysterone could accelerate bone regeneration and exhibited higher bone volume, bone surface, bone mineral density at each observation time point. Immunohistochemistry confirmed that the β-ecdysterone also increased the expression of collagen, osteocalcin, and BMP2 in the experiment group at 8 weeks. In conclusion, discovered β-ecdysterone is a new bone regeneration regulator that can stimulate MC3T3-E1 cell proliferation and induce bone regeneration through the BMP-2/Smad/Runx2/Osterix pathway. This new function of β-ecdysterone has revealed a new direction of osteogenic differentiation and has provided novel therapeutic strategies for treating bone defection.

Dataset Information

Integration of phosphatidylinositol 3-kinase, Akt kinase, and Smad signaling pathway in BMP-2-induced osterix expression.

Publications

Integration of phosphatidylinositol 3-kinase, Akt kinase, and Smad signaling pathway in BMP-2-induced osterix expression.

Similar Datasets

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