Inhibition of adenosine monophosphate-activated protein kinase suppresses bone morphogenetic protein-2-induced mineralization of osteoblasts via Smad-independent mechanisms

Endocrine journal

Ippei Kanazawa¹  Ken-ichiro Tanaka¹  Toshitsugu Sugimoto¹  Ayumu Takeno¹  Masakazu Notsu¹ 

[1]Internal Medicine 1, Shimane University Faculty of Medicine, Shimane 693-8501, Japan

关键词: Adenosine monophosphate-activated protein kinase;    Bone morphogenetic protein 2;    Osteoblast;    Smad;    Runt-related transcription factor 2;   

DOI  :  10.1507/endocrj.EJ17-0229

学科分类：内分泌与代谢学

来源: Japan Endocrine Society

【 摘 要 】

Previous studies showed that adenosine monophosphate-activated protein kinase (AMPK), which plays as an intracellular energy sensor, promotes the differentiation and mineralization of osteoblasts via enhancing expression of bone morphogenetic protein (BMP)-2, which is a potent inducer of osteoblastogenesis. Thus, the aim of this study was to examine the roles of AMPK in BMP-2-induced osteoblastogenesis. We used a murine osteoblastic cell line MC3T3-E1 and a murine marrow stromal cell line ST2. BMP-2 (50 and 100 ng/mL) stimulated alkaline phosphatase (ALP) activity and enhanced mineralization of MC3T3-E1 cells, while the effects of BMP-2 were partly abolished by an inhibitor of AMPK, ara-A (0.1 mM). Real-time PCR showed that BMP-2 significantly increased the mRNA expressions of Alp, osteocalcin (Ocn), Runx2, Osterix and Dlx-5 in MC3T3-E1 cells, while co-incubation of ara-A significantly decreased the BMP-2-stimulated expression of Alp, Ocn, and Runx2. Moreover, co-incubation of ara-A suppressed the BMP-2-induced upregulation of Alp and Ocn in ST2 cells. Western blot analysis showed that BMP-2 phosphorylated Smad1/5 although it did not affect AMPK phosphorylation in MC3T3-E1 cells. Furthermore, a BMP receptor inhibitor LDN-193189 inhibited the phosphorylation of Smad1/5, but did not affect AMPK. In addition, co-incubation of ara-A did not affect BMP-2-induced phosphorylation of Smad1/5. These findings suggest that the inhibition of AMPK activation reduces the osteo-inductive effects of BMP-2 by decreasing the expression of Alp, Ocn, and Runx2 through Smad-independent mechanisms in osteoblastic cells.

【 授权许可】

Unknown