Gene expression profiling of osteoblasts subjected to dexamethasone-induced apoptosis with/without GSK3β-shRNA.

OBJECTIVE: Glucocorticoids (GCs)-induced osteoblast apoptosis has been identified as an important cause of GCs related osteonecrosis of the femoral head (ONFH). Glycogen synthase kinase 3β (GSK3β) has been proved to mediate dexamethasone (Dex)-induced osteoblast apoptosis. This study aimed to investigate the underlying mechanism of GSK3β in Dex-induced osteoblast apoptosis.

METHODS: Osteoblast cells were transfected with lentivirus expressing GSK3β-shRNA, and a DNA microarray was performed to analyze gene expression after Dex treatment with or without GSK3β-shRNA. Some differentially expressed genes were further validated by quantitative real-time-PCR (qRT-PCR).

RESULTS: 460 genes were up-regulated (at least 2-fold) with Dex treatment but down-regulated (at least 2-fold) with GSK3β-shRNA treatment. In addition, 315 genes were down-regulated (at least 2-fold) with Dex treatment but up-regulated (at least 2-fold) with GSK3β-shRNA treatment. Among these genes, the apoptosis-related genes Hoxb8, Kif18a, Dock8, Dlk1, Tnfsf14, Casq2, Bcl2l14 and mechanosensation-related gene Piezo2 were selected for further qRT-PCR analysis. 7 of 8 genes (Piezo2, Hoxb8, Kif18a, Dlk1, Tnfsf14, Casq2, Bcl2l14) showed the same tendency between gene chip results and qRT-PCR results. The microarray data also showed that apoptotic pathway, MAPK pathway, TGFβ pathway and Wnt pathway might be related to the mechanism of GSK3β in Dex-induced osteoblast apoptosis.

CONCLUSION: Our findings indicate that GSK3β-shRNA treatment can alter various genes expression levels and change diverse signaling pathways involved in Dex-induced osteoblast apoptosis. Furthermore, Piezo2, Hoxb8, Kif18a, Dlk1, Tnfsf14, Casq2 and Bcl2l14 genes may play an important role in the GSK3β-mediated osteoblast apoptosis process.