%0 Journal Article %A Butler, Joseph S. %A Queally, Joseph M. %A Devitt, Brian M. %A Murray, David W. %A Doran, Peter P. %A O'Byrne, John M. %D 2019 %T Silencing Dkk1 expression rescues dexamethasone-induced suppression of primary human osteoblast differentiation %U https://repository.rcsi.com/articles/journal_contribution/Silencing_Dkk1_expression_rescues_dexamethasone-induced_suppression_of_primary_human_osteoblast_differentiation/10820666 %2 https://repository.rcsi.com/ndownloader/files/19330394 %K Cell Culture %K Cell Differentiation %K Cytology %K Drug Effect %K Gene Expression Regulation %K Gene Silencing %K Genetics %K Human %K Metabolism %K Osteoblast %K Physiology %K Orthopaedics %X

BACKGROUND: The 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. METHODS: 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). RESULTS: 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. CONCLUSIONS: 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.

%I Royal College of Surgeons in Ireland