Silencing Dkk1 expression rescues dexamethasone-induced suppression of primary human osteoblast differentiation.
AuthorsButler, Joseph S
Queally, Joseph M
Devitt, Brian M
Murray, David W
Doran, Peter P
O'Byrne, John M
AffiliationClinical Research Centre, UCD School of Medicine & Medical Science, Mater Misericordiae University Hospital, Dublin, Ireland. firstname.lastname@example.org
Gene Expression Regulation
Intercellular Signaling Peptides and Proteins
MetadataShow full item record
CitationSilencing Dkk1 expression rescues dexamethasone-induced suppression of primary human osteoblast differentiation. 2010, 11:210 BMC Musculoskelet Disord
JournalBMC musculoskeletal disorders
AbstractThe Wnt/β-catenin pathway is a major signaling cascade in bone biology, playing a key role in bone development and remodeling. The objectives of this study were firstly, to determine the effects of dexamethasone exposure on Wnt/β-catenin signaling at an intracellular and transcriptional level, and secondly, to assess the phenotypic effects of silencing the Wnt antagonist, Dickkopf-1 (Dkk1) in the setting of dexamethasone exposure.
Primary human osteoblasts were exposed in vitro to 10-8 M dexamethasone over a 72 h time course. The phenotypic marker of osteoblast differentiation was analyzed was alkaline phosphatase activity. Intracellular β-catenin trafficking was assessed using immunoflourescence staining and TCF/LEF mediated transcription was analyzed using a Wnt luciferase reporter assay. Dkk1 expression was silenced using small interfering RNA (siRNA).
Primary human osteoblasts exposed to dexamethasone displayed a significant reductions in alkaline phosphatase activity over a 72 h time course. Immunoflourescence analaysis of β-catenin localization demonstrated a significant reduction in intracytosolic and intranuclear β-catenin in response to dexamethasone exposure. These changes were associated with a reduction of TCF/LEF mediated transcription. Silencing Dkk1 expression in primary human osteoblasts exposed to dexamethasone resulted in an increase in alkaline phosphatase activity when compared to scrambled control.
Wnt/β-catenin signaling plays a key role in regulating glucocorticoid-induced osteoporosis in vitro. Silencing Dkk1 expression rescues dexamethasone-induced suppression of primary human osteoblast differentiation. Targeting of the Wnt/β-catenin signaling pathway offers an exciting opportunity to develop novel anabolic bone agents to treat osteoporosis and disorders of bone mass.
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