PROLIFERATION AND DIFFERENTIATION OF OSTEOBLASTS

正常的骨代谢需要骨骼之间的平衡 吸收和骨形成。 吸收骨的细胞，破骨细胞，必须 与形成骨骼的细胞成骨细胞紧密结合。 多个代理 涉及偶联剂，主要是生长因子， 细胞因子 钙最近被证明可以刺激趋化性， 成骨细胞增殖。 然而，信号转导级联 参与成骨细胞中钙刺激的趋化性的蛋白质仍然存在 未开发的 使用Boyden趋化室， 钙诱导的趋化性是基于先前的模型进行检查 建立了PDGF刺激的趋化性。 根据PDGF模型， 磷脂酶C和磷脂酰肌醇-3-激酶信号 是趋化性所必需的。 PDGF（10 ng/ml）刺激 MC 3 T3-E1成骨样细胞的趋化性是基底的17.8倍。 钙（SmM）使成骨细胞的趋化性增强7.5倍， 到基底动脉 渥曼青霉素，一种磷脂酰肌醇-3-激酶抑制剂， 显著（p<0.001）降低了PDGF刺激的趋化性。 成骨细胞减少了57% 然而，渥曼青霉素对 钙刺激的趋化性。 因此，参与的信号机制 钙诱导的MC 3 T3-E1细胞的趋化性似乎并不 利用磷脂酰肌醇-3-激酶。 U-71322，一种 磷脂酶C，显著（p<0.01）抑制PDGF刺激的 成骨细胞的趋化性降低了70%。 此外，U-71322显著 （p<0.001）使钙诱导的趋化性降低79%。 因此，我们认为， 磷脂酶C必须参与钙刺激的趋化性， MC 3 T3-E1细胞。 最近，Brown等从肾脏中克隆了一个G-连锁钙受体 和甲状旁腺细胞。 我们假设成骨细胞也 有一个G-连接的钙受体，负责最初的 在钙刺激趋化性中发现的信号事件。 未来的工作将 专注于克隆钙受体和检测下游信号 钙诱导的趋化性事件。

Normal bone metabolism requires a balance between bone resorption and bone formation. Cells that resorb bone, osteoclasts, must be tightly coupled to cells that form bone, osteoblasts. Multiple agents have been implicated as coupling agents, primarily growth factors and cytokines. Calcium has recently been shown to stimulate chemotaxis and proliferation in osteoblasts. However, the signal transduction cascade involved in calcium-stimulated chemotaxis in osteoblasts remains unexplored. Using a Boyden chemotaxis chamber, the initial signaling events in calcium-induced chemotaxis were examined based on a model previously established for PDGF-stimulated chemotaxis. According to the PDGF model, both the phospholipase C and the phosphatidylinositol-3-kinase signaling pathways are required for chemotaxis. PDGF (lOng/ml) stimulated chemotaxis of MC3T3-E1 osteoblast-like cells 17.8 times relative to basal. Calcium (SmM) enhanced chemotaxis of the osteoblasts by 7.5 times relative to basal. Wortmannin, an inhibitor of phosphatidylinositol-3-kinase, significantly (p<0.001) reduced PDGF-stimulated chemotaxis of the osteoblasts by 57%. However, wortmannin had no effect on calcium-stimulated chemotaxis. Thus, the signaling mechanism involved in calcium-induced chemotaxis of the MC3T3-E1 cells does not appear to utilize phosphatidylinositol-3-kinase. U-71322, an inhibitor of phospholipase C, significantly (p<0.01) inhibited PDGF-stimulated chemotaxis in the osteoblasts by 70%. Furthermore, U-71322 significantly (p<0.001) reduced calcium-induced chemotaxis by 79%. Therefore, phospholipase C must be involved in calcium-stimulated chemotaxis of MC3T3-E 1 cells. Recently, Brown et al. have cloned a G-linked calcium receptor from kidney and parathyroid cells. It is our hypothesis that the osteoblasts also have a G-linked calcium receptor which is responsible for the initial signaling events found in calcium-stimulated chemotaxis. Future work will focus on cloning the calcium recepto and examining downstream signaling events in calcium-induced chemotaxis.