Haem oxygenase-1 induction prevents glucocorticoid-induced osteoblast apoptosis through activation of extracellular signal–regulated kinase1/2 signalling pathway

Abstract

BackgroundHigh-dose glucocorticoid (GC) therapy always causes osteoporosis partly by inducing osteoblast apoptosis. However, the underlying mechanisms of GC-induced apoptosis remain elusive. Haem oxygenase-1 (HO-1) is a cytoprotective protein that rescues cells from H2O2 or high glucose–induced apoptosis. In bone metabolism, HO-1 also participates in osteoclast and osteoblast differentiation.ObjectiveThe present study aimed to investigate the protective role of HO-1 against GC-induced osteoblast apoptosis and to elucidate the underlying mechanism.MethodsMouse osteoblastic MC3T3-E1 cells were treated with dexamethasone (Dex) for 24 h in the presence or absence of cobalt (III) protoporphyrin IX chloride (CoPP, an inducer of HO-1). In some experiments, U0126 was added to the culture 1 h before CoPP treatment. The induction of apoptosis was determined by flow cytometry. Cell viability was evaluated using a cell counting kit-8 (CCK-8) assay. The expression levels of Bax and bcl-2 were measured by real-time polymerase chain reaction and Western blot. HO-1, extracellular signal–regulated kinase (ERK)-1/2 and pERK1/2 protein levels were measured by Western blot analysis.ResultsDex promoted apoptosis and inhibited cell viability in MC3T3-E1 cells. In addition, Dex significantly increased Bax expression and reduced Bcl-2 expression. The expression of HO-1 was also reduced after Dex treatment. HO-1 induction by CoPP significantly attenuated Dex-induced apoptosis as evidenced by Annexin V/PI staining. The mRNA expression level of antiapoptotic gene Bcl-2 was also increased after CoPP treatment. Moreover, CoPP treatment increased the phosphorylation of ERK1/2. U0126, an inhibitor of ERK activation, significantly abrogated the protective effects of CoPP.ConclusionOur results demonstrate that HO-1 induction by CoPP can attenuate Dex-induced apoptosis of mouse osteoblastic MC3T3-E1 cells. The antiapoptotic effect of HO-1 induction may be correlated with the activation of ERK1/2 signalling pathway.The translational potential of this article: HO-1 induction by CoPP can prevent GC-induced osteoblast apoptosis. Our findings will highlight the therapeutic potential of HO-1 induction in GC-induced osteoporosis.

Exploring the target and signaling pathway of Epimedium in the treatment of steroid-induced avascular necrosis of femoral head based on network pharmacology and molecular docking

“…The GO enrichment analysis showed that Epimedium mainly exerts its therapeutic effect on SANFH through cell proliferation and apoptosis, cytokine expression, and reactive oxygen reaction. The specific mechanism of SANFH remains unclear, but it is certain that the apoptosis process of osteoblasts and osteoclasts and the survival status of osteoclasts are affected by glucocorticoids [10][11][12] , and SANFH may also be associated with the hypoxia-inducible factor-1α pathway [13] . Thus, promoting angiogenesis, osteoblast differentiation, and inhibiting osteoclast proliferation through certain components can slow the onset of SANFH [14] .…”

Hedgehog Signaling Controls Bone Homeostasis by Regulating Osteogenic/Adipogenic Fate of Skeletal Stem/Progenitor Cells in Mice

“…Western blot analysis was performed as described. (50,51) The immunoreactive bands were visualized with chemiluminescence reagent (Millipore, Billerica, MA, USA), and photographed using ChemiDoc™ Touch Imaging System (Bio-Rad). Rabbit primary antibodies, including antibodies against active β-catenin and GAPDH, and horseradish peroxidase (HRP)-conjugated antirabbit secondary antibody were all purchased from Cell Signaling Technology and used at 1:2000 dilution.…”

The Protective Effect of Luteolin in Glucocorticoid-Induced Osteonecrosis of the Femoral Head

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