Enhanced and suppressed mineralization by acetoacetate and β-hydroxybutyrate in osteoblast cultures.

Akihiro Saito, Kentaro Yoshimura, Yoichi Miyamoto, Kotaro Kaneko, Daichi Chikazu, Matsuo Yamamoto, Ryutaro Kamijo

Biochemical and biophysical research communications 2016 Apr 29

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It is known that diabetes aggravates alveolar bone loss associated with periodontitis. While insulin depletion increases the blood concentration of ketone bodies, i.e., acetoacetate and β-hydroxybutyrate, their roles in bone metabolism have not been much studied until today. We investigated the effects of acetoacetate and β-hydroxybutyrate on mineralization of extracellular matrix in cultures of mouse osteoblastic MC3T3-E1 cells and primary mouse osteoblasts in the presence and absence of bone morphogenetic protein-2. Acetoacetate potentiated alkaline phosphatase activity in MC3T3-E1 cells in a concentration-dependent manner, ranging from physiological to pathological concentrations (0.05-5 mmol/L). In contrast, β-hydroxybutyrate lowered it in the same experimental settings. Mineralization in cultures of these cells was also up-regulated by acetoacetate and down-regulated by β-hydroxybutyrate. Similar results were obtained in cultures of mouse primary osteoblasts. Neither alkaline phosphatase mRNA nor its protein expression in MC3T3-E1 cells was affected by acetoacetate or β-hydroxybutyrate, indicating that these ketone bodies control the enzyme activity of alkaline phosphatase in osteoblasts and hence their mineralization bi-directionally. Finally, either gene silencing of monocarboxylate transporter-1, a major transmembrate transporter for ketone bodies, nullified the effects of ketone bodies on alkaline phosphatase activity in MC3T3-E1 cells. Collectively, we found that ketone bodies bidirectionally modulates osteoblast functions, which suggests that ketone bodies are important endogenous factors that regulate bone metabolism in both physiological and pathological situations. Copyright © 2016 Elsevier Inc. All rights reserved.

Citation

Akihiro Saito, Kentaro Yoshimura, Yoichi Miyamoto, Kotaro Kaneko, Daichi Chikazu, Matsuo Yamamoto, Ryutaro Kamijo. Enhanced and suppressed mineralization by acetoacetate and β-hydroxybutyrate in osteoblast cultures. Biochemical and biophysical research communications. 2016 Apr 29;473(2):537-44