Activation of AMP-activated protein kinase by compound 991 protects osteoblasts from dexamethasone

• Published in: Biochemical and biophysical research communications 2018-01, Vol.495 (1), p.1014-1021
• Main Authors: Xu, Yong-yi, Chen, Feng-li, Ji, Feng, Fei, Hao-dong, Xie, Yue, Wang, Shou-guo
• Format: Article
• Language: English
• Subjects: 60 APPLIED LIFE SCIENCES; AMP-Activated Protein Kinases - drug effects; AMP-Activated Protein Kinases - metabolism; AMPK; Animals; Apoptosis - drug effects; BALB 3T3 Cells; BENZIMIDAZOLES; Benzimidazoles - administration & dosage; BENZOQUINONES; CONNECTIVE TISSUE CELLS; DEXAMETHASONE; Dexamethasone - administration & dosage; Dose-Response Relationship, Drug; Drug Interactions; Enzyme Activation - drug effects; MESSENGER-RNA; Mice; NICOTINAMIDE; Nrf2; Osteoblasts; Osteoblasts - cytology; Osteoblasts - drug effects; Osteoblasts - physiology; Oxidative stress; OXYGENASES; PHOSPHOTRANSFERASES; Reactive Oxygen Species - metabolism
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2017.11.132

Dexamethasone (Dex) induces direct cytotoxicity to cultured osteoblasts. The benzimidazole derivative compound 991 (“C991”) is a novel and highly-efficient AMP-activated protein kinase (AMPK) activator. Here, in both MC3T3-E1 osteoblastic cells and primary murine osteoblasts, treatment with C991 activated AMPK signaling, and significantly attenuated Dex-induced apoptotic and non-apoptotic cell death. AMPKα1 knockdown (by shRNA), complete knockout (by CRISPR/Cas9 method) or dominant negative mutation (T172A) not only blocked C991-mediated AMPK activation, but also abolished its pro-survival effect against Dex in osteoblasts. Further studies showed that C991 boosted nicotinamide adenine dinucleotide phosphate (NADPH) activity and induced mRNA expression of NF-E2-related factor 2 (Nrf2)-regulated genes (heme oxygenase-1 and NADPH quinone oxidoreductase 1). Additionally, C991 alleviated Dex-induced reactive oxygen species (ROS) production in osteoblasts. Notably, genetic AMPK inhibition reversed the anti-oxidant actions by C991 in Dex-treated osteoblasts. Together, we conclude that C991 activates AMPK signaling to protect osteoblasts from Dex. •Compound 991 (C991) activates AMPK signaling in osteoblast cells.•C991 attenuates dexamethasone (Dex)-induced osteoblast cell death.•AMPK activation is required for C991-mediated osteoblast protection against Dex.•C991 inhibits Dex-induced oxidative stress in osteoblasts.•Genetic AMPK inhibition reverses C991's anti-oxidant actions in osteoblasts.