PROLIFERATION AND DIFFERENTIATION OF OSTEOBLASTS

正常的骨骼新陈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 与形成骨的细胞紧密结合，即成骨细胞。多个代理 被认为是偶联剂，主要是生长因子和 细胞因子。钙最近被证明可以刺激趋化性和 成骨细胞的增殖。然而，信号转导级联 成骨细胞残体参与钙离子刺激的趋化作用 未被开发的。 使用博伊登趋化室，初始信号事件在 钙诱导的趋化作用是基于先前的一个模型进行检测的。 为PDGF刺激的趋化作用而建立。根据PDGF模型， 磷脂酶C和磷脂酰肌醇-3-激酶信号转导 趋化作用需要多种途径。PDGF(长/毫升)刺激 MC3T3-E1成骨样细胞的趋化能力是基础细胞的17.8倍。 钙(SMM)促进成骨细胞趋化作用的相对倍数为7.5倍 转到基本的。Wortmannin，一种磷脂酰肌醇-3-激酶的抑制剂， 显著(p&lt；0.001)降低血小板衍生生长因子刺激的细胞趋化 成骨细胞数量增加57%。然而，Wortmannin对小鼠心脏功能没有影响 钙刺激的趋化作用。因此，涉及的信令机制 钙离子诱导的MC3T3-E1细胞趋化作用不明显 利用磷脂酰肌醇-3-激酶。U-71322，一种抗癌药物 磷脂酶C显著抑制PDGF刺激 在成骨细胞中的趋化性为70%。此外，U-71322显著 (P&lt；0.001)可使钙诱导的趋化作用降低79%。因此， 磷脂酶C必须参与钙刺激的趋化作用 MC3T3-E1细胞。 最近，Brown等人提出了自己的观点。从肾脏中克隆出一种G-连接的钙受体 和甲状旁腺细胞。我们的假设是成骨细胞也 有一种G连接的钙受体，负责初始的 钙刺激的趋化作用中发现的信号事件。未来的工作将是 关注钙受体的克隆和下游信号的检测 钙诱导趋化作用中的事件。

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.