Regulation of Osteoblast Differentiation and Function by Connexin 43

描述（由申请人提供）：低骨量疾病，如年龄依赖性骨质疏松症，对社会有深远的影响。目前用于恢复或维持骨量的疗法是有限的，并且主要集中在破骨细胞活性的减弱上。差距连接蛋白43允许成骨细胞和骨细胞之间的信号的直接细胞间通信，已显示在成骨细胞/骨细胞功能和峰值骨量的获得中起重要作用。尽管连接蛋白43在骨骼功能中具有明确的重要性，但连接蛋白43如何调节骨量获得、成骨细胞分化和成骨细胞/骨细胞功能的关键分子细节尚不清楚。如果不了解影响骨量获得的潜在分子机制，就无法设计影响骨骼疾病（如骨质疏松症）的合理疗法。事实上，任何旨在影响整个骨形成单位以逆转或减缓骨骼疾病的干预措施都需要了解成骨细胞和骨细胞之间复杂的细胞间信息交换方法，例如连接蛋白43提供的信息交换方法，以获得最佳疗效。在这项授权申请中，我们假设连接蛋白43通过调节信号转导级联的募集和激活来调节成骨细胞分化和功能，并最终调节骨质量，这些信号转导级联聚集在成骨细胞生成的主调节因子Runx 2和Osterix上。这项赠款有两个具体目标来解决这一假设。（具体目标1）确定Cx43和Cx43依赖性信号传导对Runx 2和/或Osterix水平的成骨分化的贡献;（具体目标2）确定信号复合物募集到连接蛋白43和连接蛋白43的第二信使渗透性的要求，用于成骨分化和信号传导的下游调节。我们将使用细胞和分子生物学，以及体内遗传模型来解决关键的知识缺口，关于连接蛋白43如何调节骨。通过定义这些机制，我们将获得关键的理解，连接蛋白43如何最终影响成骨细胞的功能和骨量收购。事实上，我们的长期目标是应用从这些研究中收集的知识来调节连接蛋白43的表达或连接蛋白43依赖性信号级联，无论是生理上的还是骨代谢上的，以增加骨量获得来预防或治疗骨骼脆弱性疾病。事实上，了解成骨细胞，骨细胞和破骨细胞网络的协调是至关重要的了解几乎所有的骨骼代谢疾病。

DESCRIPTION (provided by applicant): Diseases of low bone mass, like age-dependent osteoporosis, have a profound impact on society. Current therapies for the restoration or maintenance of bone mass are limited and focus primarily on the attenuation of osteoclast activity. The gap junction protein connexin 43, which permits the direct cell-to-cell communication of signals between osteoblasts and osteocytes, has been shown to play an important role in osteoblast/osteocyte function and the acquisition of peak bone mass. Despite the clear importance of connexin 43 in skeletal function, key molecular details of how connexin 43 regulates bone mass acquisition, osteoblast differentiation and osteoblast/osteocyte function are unknown. Rational therapies to impact skeletal diseases, like osteoporosis, cannot be designed without understanding the underlying molecular mechanisms affecting bone mass acquisition. Indeed, any intervention intended to impact the entire bone forming unit to reverse or slow down skeletal diseases will require an understanding of the intricate methods of intercellular exchange of information, such as those afforded by connexin 43, among osteoblasts and osteocytes for optimal efficacy. In this grant application, we hypothesize that connexin 43 regulates osteogenic differentiation and function, and ultimately bone quality, by regulating the recruitment and activation of signal transduction cascades that converge upon the master regulators of osteoblastogenesis, Runx2 and Osterix. This grant has two specific aims to address this hypothesis. (Specific Aim 1) To determine the contribution of Cx43 and Cx43-dependent signaling to osteogenic differentiation at the level of Runx2 and/or Osterix; (Specific Aim 2) To determine the requirements for both signal complex recruitment to connexin 43 and second messenger permeability by connexin 43 for downstream modulation of osteogenic differentiation and signaling. We will use cell and molecular biology, as well as in vivo genetic models to resolve key knowledge gaps, regarding how connexin 43 regulates bone. By defining these mechanisms, we will gain critical understanding of how connexin 43 ultimately affects osteoblast function and bone mass acquisition. Indeed our long-term goal is to apply the knowledge gleaned from these studies to modulate connexin 43 expression or connexin 43-dependent signaling cascades, either physiologically or pharmacologically, to increase bone mass acquisition to prevent or treat diseases of skeletal fragility. Indeed, understanding the coordination of osteoblast, osteocyte and osteoclasts networks is vital to the understanding nearly all diseases of skeletal metabolism.