Interdisciplinary Program for Bioengineering, Seoul National University, Seoul, 152-742, Korea.
J Mater Sci Mater Med. 2010 May;21(5):1649-54. doi: 10.1007/s10856-010-4011-y. Epub 2010 Feb 17.
Hydroxyapatite (HA) is a widely used calcium phosphate implant substitute and has dissolution property. Although HA has been shown a beneficial effect on osteoblast differentiation, the exact mechanism is still unclear. In the present study, we proposed that Ca(2+) released from HA activated the expression bone associated proteins, OPN and BSP, mediated by L-type calcium channel and calcium/calmodulin-dependent protein kinase (CaMK) 2 which resulted into improved osteoblast differentiation. Results showed that HA elevated ALP expression as well as OPN and BSP expression in MC3T3-E1 cells. The result from western blot of CaMK2alpha indicated that HA released Ca(2+) activated CaMK2 through L-type calcium channel. Furthermore, upregulation of OPN and BSP mRNA expression was significantly inhibited when blocking both the L-type calcium channel and CaMK2. These findings suggested that HA accelerated the osteoblast differentiation by releasing Ca(2+).
羟基磷灰石（HA）是一种广泛应用的磷酸钙植入物替代物，具有溶解性能。尽管 HA 已被证明对成骨细胞分化有有益的影响，但确切的机制仍不清楚。在本研究中，我们提出 HA 释放的 Ca(2+) 通过 L 型钙通道和钙/钙调蛋白依赖性蛋白激酶（CaMK）2 激活骨相关蛋白 OPN 和 BSP 的表达，从而促进成骨细胞分化。结果表明，HA 可提高 MC3T3-E1 细胞中碱性磷酸酶（ALP）的表达以及 OPN 和 BSP 的表达。来自 CaMK2alpha 的 Western blot 结果表明，HA 通过 L 型钙通道释放 Ca(2+) 激活 CaMK2。此外，当同时阻断 L 型钙通道和 CaMK2 时，OPN 和 BSP mRNA 表达的上调显著受到抑制。这些发现表明，HA 通过释放 Ca(2+) 加速成骨细胞分化。
