AEBP1 restores osteoblastic differentiation under dexamethasone treatment by activating PI3K/AKT signalling

Abstract

Adipocyte enhancer-binding protein 1 (AEBP1) is closely implicated in osteoblastic differentiation and bone fracture; this research aimed to investigate the effect of AEBP1 on restoring osteoblastic differentiation under dexamethasone (Dex) treatment, and its interaction with the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) pathway. Pre-osteoblastic MC3T3-E1 cells were cultured in osteogenic medium and treated by Dex to mimic steroid-induced osteonecrosis cellular model. They were then further transfected with control or AEBP1-overexpressed lentiviral vectors. Finally, cells were treated with the PI3K inhibitor LY294002, with or without AEBP1-overexpressed lentiviral vectors. AEBP1 expression showed a downward trend in MC3T3-E1 cells under Dex treatment in a dose-dependent manner. AEBP1-overexpressed lentiviral vectors increased relative cell viability, alkaline phosphatase (ALP) staining, Alizarin red staining and osteoblastic differentiation markers including osteocalcin (OCN), osteopontin (OPN), collagen type I alpha 1 (COL1A1), runt-related transcription factor 2 (RUNX2) and bone morphogenetic protein 2 (BMP2), but decreased cell apoptosis rate in MC3T3-E1 cells under Dex treatment; besides, AEBP1-overexpressed lentiviral vectors positively regulated p-PI3K and p-AKT expressions. Furthermore, LY294002 treatment decreased relative cell viability, Alizarin red staining, osteoblastic differentiation markers including OCN, OPN, RUNX2 and BMP, increased cell apoptosis rate and did not affect ALP staining in MC3T3-E1 cells under Dex treatment; meanwhile, LY294002 treatment weakened the effect of AEBP1 overexpression vectors on the above cell functions. AEBP1 restores osteoblastic differentiation under Dex treatment by activating the PI3K/AKT pathway.