Molecular Analysis of the Segementation Clock

描述(申请人提供)：脊椎动物的身体建立在一个同源异构体的组织上，该同质异构体由功能相同的单位沿前后(AP)轴重复组成，每个单位都包括一个椎骨、其相关的肌肉、周围神经和血管。然而，这些单位在轴线上并不是严格等同的，而是在不同的解剖领域表现出区域化。我们研究的目标是了解这种复杂的模式是如何在胚胎发育过程中建立的。由于脊柱复杂的神经和肌肉骨骼解剖，人类的先天性脊椎畸形是一项重大的治疗挑战。了解控制体节/脊椎花纹的遗传和发育机制对于预防这些出生缺陷将是非常宝贵的。脊椎的节段性分布来自早期胚胎体节的同源异构体模式，其产生与分子振荡器--节段钟联系在一起。在HOX基因的影响下，胚胎体节的衍生物随后被区域化，从而沿着体轴贡献了不同的解剖结构域。在这笔赠款中，我们建议继续研究鸡胚的节段性模式和随后的体轴区域化。我们将重点解决三个相关问题。在目标1中，我们将继续描述分段过程和相关振荡器。在小鼠胚胎中进行的初步微阵列研究显示，振荡器的复杂性比我们预期的要大得多。这促使我们重新考虑我们研究分段时钟机制的方法。我们建议在Aim1中移动到一个更集成的水平，并完成鸡肉分段时钟和正常和不同实验条件下的中轴旁中胚层成熟的微阵列研究。我们将利用这些实验来重建基因网络，以帮助识别时钟机制中的关键角色。在目标2中，我们将研究原始条纹中由其前体细胞产生的近轴中胚层的细节，特别关注产生该组织的部分干细胞。我们将继续研究HOX基因在旁中胚层区域化中的作用。我们最近的研究结果表明，HOX基因控制着近轴中胚层前体从上胚层进入原始条纹的过程。在目标3中，我们将尝试了解由HOX基因控制的细胞内向的分子和细胞方面。从这些研究中，我们期望获得对我们对中胚层模式形成早期阶段的分段时钟机制和HOX基因功能的理解的重要见解。

DESCRIPTION (provided by applicant): The vertebrate body is built on a metameric organization which consists of a repetition along the antero- posterior (AP) axis of functionally equivalent units, each comprising a vertebra, its associated muscles, peripheral nerves and blood vessels. These units are not, however, strictly equivalent along the axis and exhibit regionalization along the different anatomical domains. The goal of our research is to understand how this complex pattern is established during embryogenesis. Congenital vertebral malformations in humans represent a major therapeutic challenge due to the intricate neural and musculoskeletal anatomy of the spine. Understanding the genetic and developmental mechanisms which control somitic/vertebral patterning would be invaluable towards prevention of these birth defects. The segmented distribution of the vertebrae derives from the earlier metameric pattern of the embryonic somites whose production has been linked to a molecular oscillator, the segmentation clock. Under the influence of Hox genes, the derivatives of the embryonic somites become subsequently regionalized to contribute to the different anatomical domains along the body axis. In this grant, we propose to continue our studies on the segmental patterning and on the subsequent regionalization of the body axis in the chicken embryo. We will focus on three related issues. In Aim 1, we will continue our characterization of the segmentation process and of the associated oscillator. Preliminary microarray studies in the mouse embryo have revealed a far greater complexity of the oscillator than we anticipated. This led us to reconsider our approach of the study of the segmentation clock mechanism. We propose to move to a more integrated level in Aim1 and to complete a microarray study of the chicken segmentation clock and of the paraxial mesoderm maturation in normal and in various experimental conditions. We will use these experiments to reconstruct genetic networks that could help identify key players in the clock mechanism. In Aim 2, we will investigate the details of the production of the paraxial mesoderm from its progenitors in the primitive streak with a particular focus on the stem cells which generate part of this tissue. We will continue our studies of the role of Hox genes in paraxial mesoderm regionalization. Our recent results show that Hox genes control the ingression of precursors of paraxial mesoderm from the epiblast into the primitive streak. In Aim 3, we will try to understand the molecular and cellular aspects of cell ingression which are controlled by Hox genes. From these studies, we expect to gain significant insights into our understanding of the segmentation clock mechanism and of Hox gene function in early stages of mesoderm patterning.