Osteoblastic lineage cells regulate osteoclastogenesis via Cx43 and gap junctions

描述（由申请人提供）： 项目摘要/摘要骨的正常重建需要骨吸收成骨细胞和骨形成成骨细胞之间的同步活动。这种同步包括成骨细胞和破骨细胞的募集，以及破骨细胞和成骨细胞增殖和分化的刺激。骨吸收和骨形成之间的不平衡可能导致骨疾病，如骨质疏松症和骨硬化症。间隙连接（GJ）是一种跨膜通道，允许大小小于1 KD的离子和信号分子在两个相邻细胞之间通过。每个间隙连接由两个半通道或连接子组成，每个连接子由6个连接蛋白组成。骨细胞中连接蛋白的主要形式是Cx43。以往的体外研究表明，Cx43、hemicchannel和GJ调节成骨细胞、骨细胞和破骨细胞的分化和功能。然而，很少有人知道Cx43和GJIC在骨中的体内功能。为了解决这一缺陷，我们专门删除了小鼠成骨细胞和骨细胞中的Cx43。敲除小鼠表现出骨质减少表型，破骨细胞数量增加。因此，在本申请中，我们假设成骨细胞谱系细胞，包括成骨细胞和骨细胞，通过Cx43和GJIC与骨细胞通讯并抑制破骨细胞生成。我们的假设预测，降低Cx43水平和异型GJIC之间的成骨细胞系细胞和骨细胞系细胞导致骨细胞活性增加。我们将在3年的时间里完成三个目标，以研究成骨细胞系细胞是否通过Cx43和GJIC调节破骨细胞的生成：目标1，证明成骨细胞或骨细胞和骨细胞之间的Cx43介导的GJIC;目标2，定量体内和体外不同Cx43水平的成骨细胞和骨细胞诱导的破骨细胞数量和活性;目的3探讨Cx43和GJIC介导成骨细胞和骨细胞调控破骨细胞生成的机制。通过完成这些目标，我们不仅将确定Cx43和GJIC在骨骼中的新功能，而且还将确定导致骨质减少的新机制。 公共卫生相关性： 我们将研究破骨细胞是否通过Cx43介导的间隙连接细胞间通讯（GJIC）与成骨细胞谱系细胞进行通讯。此外，我们还将探讨Cx43和GJIC在成骨细胞系细胞调控破骨细胞生成中的作用和机制。拟议目标的完成将极大地有助于开发治疗骨质减少症和石骨症等骨代谢疾病的新型治疗靶点。

DESCRIPTION (provided by applicant): Project Summary/Abstract The normal remodeling of bone requires synchronized activity between bone resorbing osteoclastic and bone forming osteoblastic cells. This synchronization includes the recruitment of osteoblasts and osteoclasts, and the stimulation of osteoclast and osteoblast proliferation and differentiation. Imbalances between bone resorption and formation may lead to bone disorders, such as osteoporosis and osteopetrosis. Gap junctions (GJ) are membrane-spanning channels that allow passage of ions and signaling molecules, less than 1KD in size, between two adjacent cells. Each gap junction is composed of two hemichannels or connexons and each connexon is comprised of 6 connexins. The predominant form of connexin in bone cells is Cx43. Previous In vitro studies demonstrated that Cx43, hemichannel and GJ regulate osteoblast, osteocyte and osteoclast differentiation and function. However, little is known about the in vivo function of Cx43 and GJIC in bone. To address this deficit, we specifically deleted Cx43 in mouse osteoblasts and osteocytes. The knockout mice displayed osteopenic phenotypes with increased osteoclast number. Therefore, in this application, we hypothesize that osteoblastic lineage cells, including osteoblasts and osteocytes, communicate with osteoclastic cells and inhibit osteoclastogenesis via Cx43 and GJIC. Our hypothesis predicts that reducing Cx43 levels and heterotypic GJIC between osteoblastic lineage cells and osteoclastic lineage cells leads to increased osteoclastic activity. We will examine whether osteoblastic lineage cells regulate osteoclastogenesis via Cx43 and GJIC by completing three aims over a 3 year period: Aim 1, demonstrate Cx43-mediated GJIC between osteoblastic or osteocytic and osteoclastic cells; Aim 2, quantify osteoclast cell number and activity, both in vivo and in vitro, induced by osteoblasts and osteocytes with different Cx43 levels; and aim 3, investigate the mechanism of Cx43 and GJIC mediated osteoblastic and osteocytic cell regulated osteoclastogenesis. By completing these aims we will not only identify new functions of Cx43 and GJIC in bone, but will also identify novel mechanisms contributing to osteopenia. PUBLIC HEALTH RELEVANCE: Project Narrative We will examine whether osteoclasts communicate with osteocblastic lineage cells via Cx43 mediated gap junctional intercellular communication (GJIC). Furthermore, We will also investigate the role and mechanism of Cx43 and GJIC in osteoclastogenesis regulated by osteoblastic lineage cells. The completion of the proposed aims will greatly help to develop novel therapeutic targets for disorders of bone metabolism including osteopenias and osteopetrosis.