A role for annexin V in bone cell mechanotransduction

描述（由申请人提供）：已知骨骼的物理环境在结构活性骨的建立和维持中起重要作用。 然而，物理信号发挥这种生物效应的机制尚不清楚。 虽然生物物理信号在骨细胞中引起各种细胞反应，但这些反应的启动机制尚不清楚。 在这项研究中，我们提出，膜联蛋白V（AnxV），CA 2+依赖性磷脂结合蛋白，是一个关键的蛋白质所需的启动机械转导。 AnxV具有许多属性，这表明它非常适合作为机械感受器，可能是机械敏感离子通道。 这些包括作为Ca 2+选择性膜离子通道的能力，以及与细胞外基质蛋白如胶原蛋白和细胞骨架元件如肌动蛋白相互作用的能力。 假设：我们的中心假设是骨细胞通过需要AnxV的机制检测并将物理信号转化为生物反应。 目的：我们的目标是通过确定AnxV在骨细胞对振荡流体流动（骨中生理相关的物理信号）的反应中的作用来测试这一假设。 我们将确定AnxV作为Ca 2+选择性机械敏感性离子通道的作用是否是流动诱导的Ca 2+内流、Ca 2 +i的总体增加以及最终在人成骨细胞样MG 63细胞和鼠成骨细胞MLO-Y 4细胞中的基因表达所需的（目的1、2和3）。 我们还将确定AnxV的表达和细胞定位是否受流体流动的调节（目的4）。 重要性：这些研究的长期目标是增加我们对生物物理信号如何被骨细胞选择并转化为适当的生物反应的理解。 鉴定关键的“机械转换器”蛋白质也可能为未来治疗骨质疏松症等骨疾病的干预提供新的靶点。

DESCRIPTION (provided by applicant): The physical environment of the skeleton is known to play an important role in the establishment and maintenance of structurally competent bone. However, the mechanisms by which physical signals exert such biological effects are unclear. While biophysical signals elicit a variety of cellular responses in bone cells, the mechanism by which these responses are initiated is unknown. In this study we propose that annexin V (AnxV), a CA2+-dependent phospholipid binding protein, is a critical protein required for initiating mechanotransduction. AnxV has a number of attributes, which suggest that it is ideally suited for a role as a mechanoreceptor, possibly a mechanosensitive ion channel. These include the ability to function as a Ca2+ selective membrane ion channel, and the ability to interact with both extracellular matrix proteins such as collagen, and cytoskeletal elements such as actin. Hypothesis: our central hypothesis is that bone cells detect and transduce physical signals into biological responses via a mechanism requiring AnxV. Aims: Our goal is test this hypothesis by determining the role of AnxV in the response of bone cells to oscillating fluid flow, a physiologically relevant physical signal in bone. We will determine whether AnxV, in a role as a Ca2+ selective, mechanosensitive ion channel, is required for flow-induced Ca2+ influx, global increases in Ca2+i and ultimately gene expression in human osteoblast-like MG63 cells and murine osteocytic MLO-Y4 cells (Aims 1, 2 and 3). We will also determine whether expression and cellular location of AnxV are regulated by fluid flow (Aim 4). Significance: The long-term goal of these studies is to increase our understanding of how biophysical signals are selected and converted into an appropriate biological response by bone cells. Identification of critical "mechanotransducer" proteins may also provide novel targets for future therapeutic interventions in the fight against bone diseases such as osteoporosis.