Yoshikazu Mikami: Division of Microscopic Anatomy, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata-shi, Niigata 951-8122, Japan.
Daisuke Omagari: Department of Pathology, Nihon University School of Dentistry, 1-8-13 Kanda Surugadai Chiyoda-ku, Tokyo 101-8310, Japan.
Yusuke Mizutani: Division of Microscopic Anatomy, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata-shi, Niigata 951-8122, Japan.
Manabu Hayatsu: Division of Microscopic Anatomy, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata-shi, Niigata 951-8122, Japan.
Tatsuo Ushiki: Division of Microscopic Anatomy, Niigata University Graduate School of Medical and Dental Sciences, 1-757 Asahimachi-dori, Chuo-ku, Niigata-shi, Niigata 951-8122, Japan.
Hiromasa Tsuda: Department of Biochemistry, Nihon University School of Dentistry, 1-8-13 Kanda Surugadai Chiyoda-ku, Tokyo 101-8310, Japan. Electronic address: tsuda.hiromasa@nihon-u.ac.jp.
Inorganic polyphosphate (polyP), a linear polymer of orthophosphate, is found at high concentrations in osteoblasts. We demonstrated the effects of various polyP concentrations on the mineralization of rat osteoblastROS17/2.8 cells. Mineralization of ROS17/2.8 was induced by a high polyP concentration (1 mg/mL), which was accompanied by an upregulation of the bone sialoprotein and osteocalcin. In contrast, a low polyP concentration (1 × 10 mg/mL) reduced mineralization without affecting the osteogenic gene expression. Furthermore, gene expression profiling and forced expression analysis indicated that phosphodiesterase 11a could be a candidate involved in the dose-dependent effect of polyP on osteoblast mineralization.
