Mechanical Signaling through Osteoblast Focal Adhesions

这项建议的总体目标是了解调节合成代谢反应的细胞机制。 从骨骼到机械负荷。骨的机械负荷引起内部间质液体的运动 骨头里的空隙。流体对成骨细胞和骨细胞的机械刺激 剪应力(FSS)被认为在骨骼对机械载荷的响应中发挥作用。支持 这一假说来自于观察到FSS刺激的成骨细胞和骨细胞在 与在静态培养下保持的细胞相比，体外培养的细胞表现出更高的代谢活性 条件。这个应用程序的中心焦点是确定调节 骨细胞对其局部环境的机械敏感性。具体地说，我们建议研究一下 成骨细胞和成骨细胞之间的粘连部位(通常称为灶性接触或灶性粘连) 由整合素细胞黏附分子介导的骨细胞到细胞外基质的调节 骨细胞对FSS的反应。这项研究的结果应该能更好地理解 骨细胞力学反应的基本细胞和分子机制 通过检验焦点粘连作为机械感受器的假设，通过协调 与整合素相互作用的细胞质信号分子的活性。生理上相关的反应 骨细胞向单向和振荡液体流动包括增殖活性改变和增强 向合成代谢或成骨表型分化，基因表达改变，增加 前列腺素的产生、丝裂原活化蛋白激酶和粘着斑激酶的激活 (FAK)和胰岛素样生长因子受体(IGF-1R)对IGF-1刺激的敏化。三 提出了具体的目标。在目标1中，我们将确定破坏焦点结构完整性的影响 黏附对成骨细胞对FSS生化反应的影响。在目标2中，我们将确定焦点的作用 黏附激酶(FAK)介导的信号转导通路由FSS在机械转导中激活。在……里面 目的3确定转录因子NMP4/CIZ在信号转导中的作用 通过局部粘连激活的通路对流体剪应力作出反应。这些研究加在一起应该 提供有关骨中机械转导的细胞机制的新信息。

The overall goal of this proposal is understand the cellular mechanisms that mediate the anabolic response of bone to mechanical loading. Mechanical loading of bone induces the movement of interstitial fluid within the spaces inside bone. The resulting mechanical stimulation of osteoblasts and osteocytes caused by fluid shear stress (FSS) is hypothesized to play a role in the response of bone to mechanical loading. Support for this hypothesis comes from the observation that osteoblasts and osteocytes that are stimulated by FSS in vitro exhibit increased metabolic activity compared to cells that are maintained under static culture conditions. The central focus of this application is to determine the cellular mechanisms that mediate the mechanical sensitivity of bone cells to their local environment. Specifically, we propose to examine the role of adhesion sites (commonly referred to as focal contacts or focal adhesions) between osteoblasts and osteocytes to the extracellular matrix that are mediated by integrin cell adhesion molecules in regulating the response of bone cells to FSS. The results of this study should provide an improved understanding of the fundamental cellular and molecular mechanisms that mediate the response of bone cells to mechanical loading by testing the hypothesis that focal adhesions function as mechanoreceptors by coordinating the activity of cytoplasmic signaling molecules that interact with integrins. Physiologically relevant responses by bone cells to unidirectional and oscillatory fluid flow include altered proliferative activity and enhanced differentiation toward an anabolic or osteoblastic phenotype, altered gene expression, increased prostaglandin production, activation of mitogen activated protein kinases (MAPK) and focal adhesion kinase (FAK) and sensitization of the insulin-like growth factor receptor (IGF-1R) to stimulation by IGF-1. Three specific aims are proposed. In Aim 1 we will determine the effect of disrupting the structural integrity of focal adhesions on biochemical response of osteoblasts to FSS. In Aim 2 we will determine the role of focal adhesion kinase (FAK) mediated signal transduction pathways activated by FSS in mechanotransduction. In Aim 3 we will determine the role of the transcription factor NMP4/CIZ in mediating signal transduction pathways activated through focal adhesions in response to fluid shear stress. Together these studies should provide novel information on the cellular mechanisms that mediate mechanotransduction in bone.