Menaquinone-7 regulates the expressions of osteocalcin, OPG, RANKL and RANK in osteoblastic MC3T3E1 cells

• Published in: International journal of molecular medicine Vol. 15; no. 2; p. 231
• Main Authors: Katsuyama, Hironobu, Otsuki, Takemi, Tomita, Masafumi, Fukunaga, Masao, Fukunaga, Tatsushige, Suzuki, Nobuo, Saijoh, Kiyofumi, Fushimi, Shigeko, Sunami, Shigeo
• Format: Journal Article
• Language: English
• Published: Greece 01.02.2005
• Subjects: Animals; Carrier Proteins - biosynthesis; Cell Differentiation; Cell Line; Cell Proliferation; Glycoproteins - biosynthesis; Hemostatics - metabolism; Hemostatics - pharmacology; Immunohistochemistry; Membrane Glycoproteins - biosynthesis; Mice; Mice, Inbred C57BL; NF-kappa B - metabolism; Osteoblasts - metabolism; Osteocalcin - biosynthesis; Osteoprotegerin; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Receptors, Cytoplasmic and Nuclear - biosynthesis; Receptors, Tumor Necrosis Factor - biosynthesis; Reverse Transcriptase Polymerase Chain Reaction; RNA - metabolism; RNA, Messenger - metabolism; Time Factors; Vitamin K 2 - analogs & derivatives; Vitamin K 2 - metabolism; Vitamin K 2 - pharmacology
• ISSN: 1107-3756

Epidemiological studies show that dietary intake of natto, which contains significant amount of vitamin K(2), reduces the risk of bone formation loss. However, many confounding factors, such as calcium and isoflavone, are found in natto, because it is made from soybeans. In this study, the direct effects of MK-7, a vitamin K(2) analogue, were assessed in osteoblasts. Osteoblastic MC3T3E1 cells were cultured with or without MK-7 for 10 days and the number of cells was calculated. The cell count was not different between MK-7 treated cells and control cells for 1, 2, and 4 days. However, it was significantly suppressed in MK-7 treated cells at 10 days, suggesting that MK-7 suppressed cell proliferation. Real-time PCR analysis showed that mRNAs of osteocalcin (OC), osteoprotegerin (OPG), and the receptor activator of the NFkappaB ligand (RANKL) were induced after MK-7 administration to the culture medium. RANK mRNA expression was also enhanced by MK-7 administration. Immunocytochemical analysis showed that MK-7 increased the protein levels of OC and RANKL. RANK protein was also enhanced, but this induction was suppressed by anti-RANK antibody administration. This suppression was recovered when anti-RANK antibody and MK-7 were administered. These observations suggest that MK-7 may directly affect MC3T3E1 cells and stimulate osteoblastic differentiation, not proliferation.