Intercellular Signaling in Bone

描述（由申请人提供）：间隙连接蛋白connexin43的突变或功能丧失导致骨骼异常、延迟骨化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。我们之前的研究表明，通过间隙连接的细胞间通讯缺失导致的基因转录下调是细胞信号改变导致转录因子募集到受影响基因启动子的调节的结果。需要评估的总体假设是，间隙连接通信需要引起细胞对细胞外信号的最佳反应来调节基因转录。这些问题将在三个特定的目标中得到解决：(1)分析间隙连接在调节信号转导中的作用，以响应细胞外信号来调节成骨细胞的功能。(2)确定相互作用的分子基础，这些相互作用允许从间隙连接信号传导。(3)研究Ca2+依赖性信号在cx43介导的基因转录中的作用。通过对间隙连接通道、由间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，我们将大大阐述我们在调节成骨细胞功能的背景下对间隙连接功能的认识和理解。这些目标将通过从Cx43缺陷小鼠中提取的成骨细胞系和原代成骨细胞来实现。意义：该研究将揭示间隙连接蛋白在细胞外信号的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间隙连接通讯来增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疾病的方法。

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.