Gap Junctions/Limb Outgrowth, Patterning, Skeletogenesis

间隙连接/肢体生长、图案形成、骨骼发生

• 批准号: 6692600
• 负责人: Caroline N Dealy
• 金额: $ 7.25万
• 依托单位: UNIVERSITY OF CONNECTICUT SCH OF MED/DNT
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-01-01 至 2005-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6692600
• 关键词: bone development; cartilage development; cell proliferation; chick embryo; ectoderm; gap junctions; gene targeting; genetically modified animals; immunocytochemistry; in situ hybridization; laboratory mouse; limb bone; mesoderm; northern blottings; osteogenesis; skeletal system; western blottings

DESCRIPTION (provided by applicant): The goal of this application is to study the role of gap junctional communication in vertebrate limb outgrowth and patterning, and during limb skeletal element formation. I). Limb outgrowth and patterning is controlled by interactions between the apical ectodermal ridge (AER), a specialized ectodermal structure located at the distal tip of the limb which directs the proliferation and proximodistal outgrowth of the limb mesoderm, and the zone of polarizing activity (ZPA), a group of mesoderm cells located at the posterior periphery of the limb which is thought to specify positional values across the anterior-posterior limb axis. Our previous studies indicate that extensive gap junctional communication occurs among the cells of the AER itself, and among the cells of the posterior and distal mesoderm which is undergoing outgrowth and patterning in response to signals from the AER and ZPA. Our studies also show that abundant expression of the gap junction gene Cxn43 correlates with these regions. In these proposed studies, we will test the hypothesis that gap junctions composed of Cxn43 play an important role in AER activity, limb outgrowth and patterning. We will examine the effects of modulation of gap junctional communication in the AER and limb mesoderm achieved by missexpression of Cxn43, antisense Cxn43, or of mutated or modified Cxn43 via retroviral vectors in the chick limb in ovo, or via an AER-specific enhancer element in transgenic mice. II). The initial phase of limb skeletal element formation is characterized by the formation of pre-cartilage mesenchymal condensations, which differentiate to become the cartilage models of the limb. The chondrocytes of the cartilage models undergo progressive maturation leading to the replacement of cartilage by bone during endochondral ossification. Our previous studies show that gap junctional communication increases dramatically during condensation of limb pre-cartilage mesenchyme, and that Cxn43 is transiently expressed by condensing cartilage. Other studies have also implicated Cxn43-containing gap junctions in chondrocyte maturation and osteogenic differentiation. In these proposed studies, we will test the hypothesis that gap junctions composed of Cxn43 are involved in chondrogenesis and/or osteogenesis of the limb skeletal elements. We will examine the effects of modulation of gap junctional communication during skeletogenesis achieved as above via retroviral vectors in the chick limb in ovo, or via a cartilage-specific enhancer element in the limbs of transgenic mice.

描述（由申请人提供）：本申请的目的是研究间隙连接通讯在脊椎动物肢体生长和形成模式中以及在肢体骨骼元件形成期间的作用。（一）。肢体生长和模式化是由顶端外胚层嵴（AER）和极化活动区（ZPA）之间的相互作用控制的，AER是位于肢体远端的特化外胚层结构，指导肢体中胚层的增殖和近远侧生长，一组中胚层细胞位于肢的后周边，被认为指定了前边缘的位置值，后肢轴我们以前的研究表明，广泛的缝隙连接通信发生在AER本身的细胞之间，以及在后中胚层和远中胚层的细胞之间，这些细胞响应于来自AER和ZPA的信号而进行生长和图案化。我们的研究还表明，差距连接基因Cxn 43的丰富表达与这些区域相关。在这些拟议的研究中，我们将测试的假设，间隙连接组成的Cxn 43在AER活动，肢体生长和图案中发挥重要作用。我们将研究通过Cxn 43，反义Cxn 43，或突变或修饰的Cxn 43通过逆转录病毒载体在卵内鸡肢中，或通过AER特异性增强子元件在转基因小鼠中的错误表达所实现的AER和肢中胚层间隙连接通讯的调制效果。II）。肢体骨骼元素形成的初始阶段的特征在于前软骨间充质凝聚的形成，其分化成为肢体的软骨模型。软骨模型的软骨细胞经历逐渐成熟，导致在软骨内骨化期间软骨被骨替代。我们以前的研究表明，间隙连接通讯显着增加，在四肢前软骨间充质冷凝，Cxn 43是瞬时表达冷凝软骨。其他研究也涉及软骨细胞成熟和成骨分化中含有Cxn 43的间隙连接。在这些拟议的研究中，我们将测试的假设，间隙连接组成的Cxn 43参与软骨和/或骨形成的肢体骨骼元素。我们将研究在骨骼发育过程中通过逆转录病毒载体在鸡肢卵中或通过软骨特异性增强子元件在转基因小鼠四肢中实现的缝隙连接通讯的调节作用。