Heparin potentiates the in vivo ectopic bone formation induced by bone morphogenetic protein-2
Heparin potentiates the in vivo ectopic bone formation induced by bone morphogenetic protein-2
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DOI：
10.1074/jbc.m511039200
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发表时间：
2006-08-11
影响因子：
4.8
通讯作者：
Kamijo, Ryutaro
中科院分区：
文献类型：
--
作者：
Zhao, Baohong;Katagiri, Takenobu;Kamijo, Ryutaro
虽然骨形态发生蛋白(BMP)在临床上对骨再生很有用，但在猴子和人类身上诱导新骨形成需要大量的BMP。我们最近发现肝素在体外刺激BMP活性(Takada，T.，Katagiri，T.，Ifuku，M.，Morimura，N.，Kobayashi，M.，Hasegawa，K.，Ogamo，A.，and Kamijo，R.(2003)J.Biol)。化学。278、43229-43235)。在本研究中，我们研究了肝素在体内是否促进了BMPs诱导的骨形成，并试图通过C2C12成肌细胞来确定肝素刺激BMP活性的分子机制。肝素可促进BMP-2诱导的基因表达和Smad1/5/8的磷酸化，但在12h内不能。肝素酶处理不影响细胞对BMP-2的反应。在肝素存在下，BMP-2的降解被阻止，BMP-2在培养液中的半衰期延长了近20倍。无论有无肝素存在，noggin-2均可在1h内被BMP-2诱导表达，但在肝素存在下，noggin不能抑制BMP-2的活性。此外，与单独应用BMP-2相比，体内同时应用BMP-2和肝素可诱导更多的矿化骨组织，且呈剂量依赖关系。这些发现清楚地表明，肝素不仅在体外而且在体内都能促进BMP诱导的成骨细胞分化。本研究表明，肝素通过保护BMP不被BMP拮抗剂降解和抑制，在体外和体内促进BMP诱导的成骨细胞分化。
Although bone morphogenetic proteins (BMPs) are clinically useful for bone regeneration, large amounts are required to induce new bone formation in monkeys and humans. We found recently that heparin stimulates BMP activity in vitro (Takada, T., Katagiri, T., Ifuku, M., Morimura, N., Kobayashi, M., Hasegawa, K., Ogamo, A., and Kamijo, R. (2003) J. Biol. Chem. 278, 43229-43235). In the present study, we examined whether heparin enhances bone formation induced by BMPs in vivo and attempted to determine the molecular mechanism by which heparin stimulates BMP activity using C2C12 myoblasts. Heparin enhanced BMP-2-induced gene expression and Smad1/5/8 phosphorylation at 24 h and thereafter, although not within 12 h. Heparitinase treatment did not affect the response of cells to BMP-2. In the presence of heparin, degradation of BMP-2 was blocked, and the half-life of BMP-2 in the culture medium was prolonged by nearly 20-fold. Although noggin mRNA was induced by BMP-2 within 1 h regardless of the presence of heparin, noggin failed to inhibit BMP-2 activity in the presence of heparin. Furthermore, simultaneous administration of BMP-2 and heparin in vivo dose-dependently induced larger amounts of mineralized bone tissue compared with BMP-2 alone. These findings clearly indicate that heparin enhances BMP-induced osteoblast differentiation not only in vitro but also in vivo. This study indicates that heparin enhances BMP-induced osteoblast differentiation in vitro and in vivo by protecting BMPs from degradation and inhibition by BMP antagonists.