ROLE OF XHOX HOMEOBOX GENES IN XENOPUS DEVELOPMENT

最近发育生物学的一个焦点是分离和研究基因。 做出细胞命运和构图的关键决定 胚胎发生。对果蝇的遗传学研究表明，基因 含有同源框DNA结合基序的参与 其他基因，如脊椎动物的Myo-D基因，也有 发育调节器的令人信服的特性。我们建议研究 非洲爪哇胚胎的区域规格和模式形成 焦点是Xhox-1同源框基因和Myo-D基因。 在之前的工作中，我们设计了一种过表达分析来解决 Xhox-1A基因的功能，并证明它很可能是 参与体节形成的。体细胞发生是一个主要的分段 塑造脊椎动物身体玩耍的事件。这一发现意义重大 因为这是脊椎动物功能的第一个迹象 同源异型盒基因，它实现了同源异型盒基因的广泛预期 将参加关键的发展活动。我们建议研究 此外，Xhox-1a和一个连锁基因的作用。Xhox-1B，SOMITE 队形。我们将使用抗体在细胞分辨率下进行研究 这些基因的正常表达模式。此外，我们还将设计 Xhox-1基因的显性作用突变体将用于 对抗内源基因的作用，从而扰乱 以新的方式进行体细胞发生。我们还将探讨同源异型盒基因的功能 在生化水平上研究Xhox-1A蛋白与 DNA我们相信，从长远来看，这种生化方法将 揭示稳定的发育变化是如何受到影响的。 在非洲爪哇，大部分体节组织变成肌肉。什么都不知道 关于肌肉组织的图案化(躯体发生)如何与 对肌肉血统的承诺。有证据表明，Myo-D基因 在这一承诺步骤中是有启发意义的。我们将描述 非洲爪蛙Myo-D基因在早期发育过程中的表达 设计功能分析来测试Myo-D基因表达是否可以 多能的胚胎外胚层直接进入肌肉谱系。 这些实验旨在研究细胞的具体例子 脊椎动物发育中的承诺和模式。此外，我们还将 采取更笼统的方法来解决地区性如何 规格发生在胚胎中。我们将筛选出一个原肠胚前期的基因 带有发育相关基因探针的文库，如其他 同源异型盒基因，认为它们中的许多会表现出受限的空间 表达，并将指示早期阶段的细胞承诺区。 这项提议的优点在于，我们已经有了一个 我们研究的同源异型盒基因的功能分析 我们可以将这些研究与丰富的细胞和 非洲爪哇胚胎的发育信息。

A recent focus of development biology has been to isolate and study genes through to make critical decisions of cell fate and patterning in embryogenesis. Genetic studies in Drosophila indicate that genes containing the homeobox DNA-binding motif participate in such decisions.Other genes such as the vertebrate Myo-D gene, also have the compelling properties of developmental regulators. We propose to study regional specification and pattern formation in Xenopus embryos using as a focus the Xhox-1 homeobox genes and the Myo-D gene. In previous work we devised an overexpression assay to address the function of the Xhox-1A gene and demonstrated that it is likely to be involved in somite formation. Somitogenesis is a primary segmentation event which shapes the vertebrate body play. This finding is significant because it is the very first indication of a function for a vertebrate homeobox gene and it fulfills the broad expectation that homeobox genes will participate in critical developmental events. We propose to study further the role of Xhox-1A and a linked gene. Xhox-1B, in somite formation. We will use antibodies to investigate at cellular resolution the normal expression pattern of these genes. Furthermore, we will design dominant-acting mutants of the Xhox-1 genes which will be used to antagonize the action of the endogenous genes and thus perturb somitogenesis in new ways. We will also approach homeobox gene function at the biochemical level by studying the binding of Xhox-1A protein to DNA. We believe that in the long term this biochemical approach will reveal how stable developmental changes are affected. In Xenopus, most of the somite tissue becomes muscle. Nothing is known about how the patterning of muscle tissue (somitogenesis) meshes with commitment to the muscle lineage. Evidence suggests that the Myo-D gene is instructive in this commitment step. We will characterize the expression of the Xenopus Myo-D during early development and attempt to devise functional assays to test whether Myo-D gene expression can commit multipotent, embryonic ectoderm directly into the muscle lineage. These experiments are designed to investigate specific examples of cell commitment and patterning in vertebrate development. In addition, we will take a more general approach to the fundamental problem of how regional specification occurs in embryos. We will screen a pre-gastrulation cDNA library with probes for developmentally interesting genes such as other homeobox genes, believing that many of them will show restricted spatial expression and will indicate zones of cell commitment at early stages. The strength of this proposal lies in the fact that we already have a functional assay for the homeobox genes that we study and in the fact that we can relate these studies to the wealth of cellular and developmental information available for Xenopus embryos.