Molecular mechanisms of N-myc gene regulation during mammalian embryonic development

从受精卵发育成多细胞生物体是一个复杂的过程，涉及到遗传信息在精确的空间和时间模式上的差异表达。在哺乳动物中，胚胎发育包括早期分化事件，这使得胚胎能够在子宫环境中生存，以及一个过程，在这个过程中，多潜能细胞池增殖，随后分化形成胎儿原基。高度复杂的形态发生事件，与器官发生一起，将确定胎儿的最终身体计划。发育中胚胎不同部分的相互依赖表明了某种形式的分级控制，在这种控制中，信号分子和转录调节因子相互作用，以协调的方式调节结构基因组的活动。识别和鉴定参与这些调控机制的基因对于我们理解哺乳动物的发育过程至关重要。许多癌基因作为转录因子在胚胎中的表达模式表明这些基因在哺乳动物发育中发挥了作用。在我们的实验室里，我们之前已经证明了癌基因和转录因子N-myc对于哺乳动物的正常发育是必不可少的。N-myc的功能可能涉及通过促进前体细胞的生长、抑制其死亡和控制其终末分化来放大前体细胞。因此，对N-myc调控机制的研究是我们理解细胞生长和分化过程的关键步骤。在目前的应用中，我们建议检查在小鼠胚胎发育过程中对N-myc基因表达进行适当调控的要求，以确定N-myc表达限制性结构域的分子机制。总体而言，所提出的实验构成了一种综合的方法，结合了遗传、分子和生化分析，应该可以提供关于这一重要癌基因调控机制的宝贵信息。

The development of a multicellular organism from the fertilized egg is a complex process involving differential expression of the genetic information in a precise spatial and temporal pattern. In mammals, embryonic development involves early differentiation events, which permit the embryo to survive in the uterine environment, as well as a process during which a pool of pluripotential cells proliferates and subsequently diverges to generate the fetal primordia. Highly complex morphogenetic events, together with organogenesis, will then establish the definitive body plan of the fetus. The interdependence of various parts of the developing embryo suggests some form of hierarchical control in which signaling molecules and transcriptional regulators interact to modulate the activity of groups of structural genes in a concerted fashion. The identification and the characterization of genes involved in these mechanisms of control are essential to our understanding of the mammalian developmental processes. The embryonic expression pattern of many oncogenes acting as transcriptional factors suggests a role for these genes in mammalian development. In our laboratory, we have previously shown that the oncogene and transcriptional factor N-myc is essential for normal mammalian development. The N-myc function might involve the amplification of precursor cells by promoting their growth, inhibiting their death, and controlling their terminal differentiation. Therefore, the characterization of the mechanisms of regulation of N-myc is a critical step for our understanding of the processes of cell growth and differentiation. In the present application, we propose to examine the requirements for the appropriate regulation of N-myc gene expression during mouse embryogenesis in order to determine the molecular mechanisms responsible for the N-myc restricted domains of expression. Overall, the experiments proposed constitute a comprehensive approach combining genetic, molecular and biochemical analyses that should provide invaluable information on the mechanisms involved in the regulation of this important oncogene.