Intercellular Signaling in Bone

描述(申请人提供)：缝隙连接蛋白43的突变或功能丧失导致骨骼异常、延迟成骨和全身性成骨细胞功能障碍，其特征是成骨细胞基因转录减少和矿化潜力降低。我们以前的研究表明，通过缝隙连接失去细胞间通讯所导致的基因转录下调是细胞信号改变的结果，导致转录因子向受影响基因的启动子招募的调节。有待评估的总体假设是，缝隙连接通讯需要诱导细胞对细胞外信号的最佳反应，以调节基因转录。这些问题将通过三个具体的目标来解决：(1)分析缝隙连接在调节细胞外信号转导中的作用，以调节成骨细胞的功能。(2)确定允许缝隙连接信号转导的相互作用的分子基础。(3)研究钙依赖信号在Cx43介导的基因转录中的作用。通过对缝隙连接通道、由缝隙连接传播的信使以及由这些信号激活的信号级联进行三角测量，我们将在成骨细胞功能调节的背景下详细阐述我们对缝隙连接功能的认识和理解。这些目标将使用具有良好特性的成骨细胞系和来自Cx43缺陷小鼠的原代成骨细胞来实现。意义：这些研究将深入了解缝隙连接蛋白在细胞外信号协调和传播中的分子功能，以及这些信号如何在细胞核水平上调节细胞功能。我们的长期目标是通过调节缝隙连接通讯来加强生长因子对骨形成的合成代谢反应，从而开发预防和治疗骨骼病理的方法。

DESCRIPTION (provided by applicant): The mutation or loss of function of the gap junction protein connexin43 leads to skeletal abnormalities, delayed ossification and a generalized osteoblast dysfunction, characterized by diminished osteoblast gene transcription and decreased mineralization potential. We have previously characterized that the down regulation of gene transcription caused by loss of intercellular communication through gap junctions is a result of altered cell signaling leading to regulation of the recruitment of transcription factors to the promoter of affected genes. The overall HYPOTHESIS to be evaluated is that gap junctional communication is required to elicit the optimal response of cells to extracellular cues to modulate gene transcription. These issues will be addressed in three SPECIFIC AIMS that will: (1) Analyze the role of gap junction in regulating signal transduction in response to extracellular signals to regulate osteoblast function. (2) Determine the molecular basis of interactions which permit signal transduction from the gap junction signaling nexus. (3) Examine the role of Ca2+dependent signaling in Cx43-mediated gene transcription. By triangulating on the gap junction channel, the messenger propagated by the gap junction, and the signal cascades activated by these signals, we will greatly elaborate on our knowledge and understanding of gap junction function in the context of regulating osteoblast function. These aims will be carried out using well characterized osteoblastic cell lines and primary osteoblasts derived from Cx43 deficient mice. SIGNIFICANCE: The studies will provide insight into the molecular function of gap junction proteins in the coordination and propagation of extracellular signals and how these signals regulate cellular function at the level of the nucleus. Our long term goal is to develop methods for the prevention and treatment of skeletal pathologies by modulating gap junctional communication to potentiate the anabolic response of growth factors on bone formation.