Emodin Regulates Bone Remodeling by Inhibiting Osteoclastogenesis and Stimulating Osteoblast Formation

Authors

  • Ju-Young Kim,

    1. Imaging Science-based Lung and Bone Diseases Research Center, Wonkwang University, Iksan, Korea
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  • Yoon-Hee Cheon,

    1. Department of Anatomy, School of Medicine, Wonkwang University, Iksan, Korea
    2. BK21plus program & Department of Smart Life-Care Convergence Graduate School, Wonkwang University, Iksan, Korea
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  • Sung Chul Kwak,

    1. Department of Anatomy, School of Medicine, Wonkwang University, Iksan, Korea
    2. BK21plus program & Department of Smart Life-Care Convergence Graduate School, Wonkwang University, Iksan, Korea
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  • Jong Min Baek,

    1. Department of Anatomy, School of Medicine, Wonkwang University, Iksan, Korea
    2. BK21plus program & Department of Smart Life-Care Convergence Graduate School, Wonkwang University, Iksan, Korea
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  • Kwon-Ha Yoon,

    1. Imaging Science-based Lung and Bone Diseases Research Center, Wonkwang University, Iksan, Korea
    2. Department of Radiology, School of Medicine, Wonkwang University, Iksan, Korea
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  • Myeung Su Lee,

    Corresponding author
    1. Imaging Science-based Lung and Bone Diseases Research Center, Wonkwang University, Iksan, Korea
    2. Department of Anatomy, School of Medicine, Wonkwang University, Iksan, Korea
    3. Institute for Skeletal Disease, Wonkwang University, Iksan, Korea
    • Address correspondence to: Jaemin Oh, PhD, Department of Anatomy, School of Medicine, Wonkwang University, 344-2 Sinyong-dong, Iksan, Jeonbuk 570-749, Korea. E-mail: jmoh@wku.ac.kr; Myeung Su Lee, PhD, Division of Rheumatology, Department of Internal Medicine, School of Medicine, Wonkwang University, 344-2 Sinyong-dong, Iksan, Jeonbuk 570-749, Korea. E-mail: ckhlms@wku.ac.kr

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  • Jaemin Oh

    Corresponding author
    1. Imaging Science-based Lung and Bone Diseases Research Center, Wonkwang University, Iksan, Korea
    2. Department of Anatomy, School of Medicine, Wonkwang University, Iksan, Korea
    3. BK21plus program & Department of Smart Life-Care Convergence Graduate School, Wonkwang University, Iksan, Korea
    4. Institute for Skeletal Disease, Wonkwang University, Iksan, Korea
    5. Division of Rheumatology, Department of Internal Medicine, Wonkwang University, Iksan, Korea
    • Address correspondence to: Jaemin Oh, PhD, Department of Anatomy, School of Medicine, Wonkwang University, 344-2 Sinyong-dong, Iksan, Jeonbuk 570-749, Korea. E-mail: jmoh@wku.ac.kr; Myeung Su Lee, PhD, Division of Rheumatology, Department of Internal Medicine, School of Medicine, Wonkwang University, 344-2 Sinyong-dong, Iksan, Jeonbuk 570-749, Korea. E-mail: ckhlms@wku.ac.kr

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ABSTRACT

Bone remodeling, a physiological process in which new bone is formed by osteoblasts and the preexisting bone matrix is resorbed by osteoclasts, is vital for the maintenance of healthy bone tissue in adult humans. Imbalances in this process can cause various pathological conditions, including osteoporosis. Emodin, a naturally occurring anthraquinone derivative found in Asian herbal medicines, has numerous beneficial pharmacologic effects, including anticancer and antidiabetic activities. However, the effect of emodin on the regulation of osteoblast and osteoclast activity has not yet been investigated. We show here that emodin is a potential target for osteoporosis therapeutics, as treatment with this agent enhances osteoblast differentiation and bone growth and suppresses osteoclast differentiation and bone resorption. In this study, emodin suppressed receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL)-induced osteoclast differentiation of bone marrow macrophages (BMMs) and the bone-resorbing activity of mature osteoclasts by inhibiting RANKL-induced NF-κB, c-Fos, and NFATc1 expression. Emodin also increased ALP, Alizarin Red-mineralization activity, and the expression of osteoblastogenic gene markers, such as Runx2, osteocalcin (OCN), and ALP in mouse calvarial primary osteoblasts, as well as activated the p38-Runx2 pathway, which enhanced osteoblast differentiation. Moreover, mice treated with emodin showed marked attenuation of lipopolysaccharide (LPS)-induced bone erosion and increased bone-forming activity in a mouse calvarial bone formation model based on micro-computed tomography and histologic analysis of femurs. Our findings reveal a novel function for emodin in bone remodeling, and highlight its potential for use as a therapeutic agent in the treatment of osteoporosis that promotes bone anabolic activity and inhibits osteoclast differentiation. © 2014 American Society for Bone and Mineral Research.

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