Cytoskeletal Strain Amplification due to Bone Fluid Flow

骨液流动引起的细胞骨架应变放大

• 批准号: 7056809
• 负责人: Sheldon Weinbaum
• 金额: $ 30.88万
• 依托单位: CITY COLLEGE OF NEW YORK
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2008-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7056809
• 关键词: actins; bone development; confocal scanning microscopy; cytoplasm; cytoskeleton; digital imaging; electron microscopy; fluid flow; immunocytochemistry; immunoelectron microscopy; laboratory mouse; laboratory rat; mechanical pressure; mechanoreceptors; osteocytes; protein structure; proteoglycan; transmission electron microscopy; actins; bone development; confocal scanning microscopy; cytoplasm; cytoskeleton; digital imaging; electron microscopy; fluid flow; immunocytochemistry; immunoelectron microscopy; laboratory mouse; laboratory rat; mechanical pressure; mechanoreceptors; osteocytes; protein structure; proteoglycan; transmission electron microscopy

DESCRIPTION (provided by applicant): Bone adapts readily to its mechanical loading environment. The "mechanosensor" for this adaptation is widely believed to be the osteocyte, though the actual process is both unknown and critical to understanding the process of new bone formation. However, there is an emerging consensus that strain-induced interstitial fluid flow plays a key role in this mechanical signaling. In this proposal we address a new question: How would the osteocyte "perception" of fluid flow be influenced by the presence of a pericellular matrix with transverse filaments that both tether the cell process to the canalicular wall and transmit fluid dynamic drag forces on the tethering filaments to the intracellular actin cytoskeleton in the cell processes? Our pilot studies have revealed the first clear identification of such transverse bridging fibers and a new theoretical model (You et al., 2001) has been developed to quantitatively explore this hypothesis. This model makes the remarkable prediction that the very small mechanical strains in live bone can be amplified 100-fold at the cellular level. If validated, the model resolves a fundamental paradox. It explains why tissue level strains in whole bone can be so much smaller than that measured in vitro dynamic substrate strains required to elicit intracellular biochemical responses. In the proposed studies, we will experimentally verify and measure the essential biological elements required by this new model. In particular, we will: (1) characterize the spacing and distribution of the transverse elements that tether the cell process to the canalicular wall; (2) identify, using immunohistochemical staining techniques, the proteoglycans that fill the pericellular space; (3) elucidate the structure of the actin filament bundle that fills the cell process; and (4) refine the theoretical model for predicting the cellular level strain amplification that occurs in the cell process due to the fluid drag on the pericellular matrix.

描述（由申请人提供）：骨很容易适应其机械 加载环境。人们普遍认为，这种适应的“机械传感器” 成为骨细胞，尽管实际过程对 了解新骨形成的过程。但是，有一个新兴 应变引起的间质流体流动在这方面起关键作用的共识 机械信号传导。在此提案中，我们解决了一个新问题： 流体流的骨细胞“感知”受A的存在影响 周围的细胞基质和横向丝，均绑在细胞过程 到管壁并在束缚上传递流体动态阻力 细胞过程中细胞内肌动蛋白细胞骨架的细丝？我们的 试点研究揭示了这种横向的第一个明确鉴定 桥接纤维和一个新的理论模型（You等，2001）已经是 开发用于定量探索这一假设。该模型使 显着的预测，活骨中的机械菌株很小 在细胞水平上放大100倍。如果得到验证，模型可以解决 基本悖论。它解释了为什么整个骨骼中的组织水平菌株可能是 比在体外动态底物菌株中测得的小得多 引起细胞内生化反应。在拟议的研究中，我们将 实验验证并测量由 这个新模型。特别是：（1）特征间距和 将细胞过程绑定到该细胞过程的横向元素的分布 口腔壁； （2）使用免疫组织化学染色技术确定 充满细胞周围空间的蛋白聚糖； （3）阐明结构 充满细胞过程的肌动蛋白丝束； （4）完善 预测细胞水平应变扩增的理论模型 由于周围基质上的流体阻力，发生在细胞过程中。