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

从受精卵到多细胞生物体的发育是一个复杂的过程，涉及遗传信息在精确的空间和时间模式中的差异表达。在哺乳动物中，胚胎发育涉及早期分化事件，其允许胚胎在子宫环境中存活，以及多能细胞池增殖并随后分叉以产生胎儿原基的过程。高度复杂的形态发生事件，连同器官发生，将建立胎儿的最终身体计划。发育中的胚胎各部分的相互依赖性表明了某种形式的分级控制，其中信号分子和转录调节因子相互作用，以协调一致的方式调节结构基因组的活性。这些控制机制中涉及的基因的鉴定和表征对于我们理解哺乳动物的发育过程是至关重要的。许多作为转录因子的癌基因在胚胎中的表达模式表明这些基因在哺乳动物发育中的作用。在我们的实验室中，我们以前已经表明，癌基因和转录因子N-myc是必不可少的正常哺乳动物的发展。N-myc的功能可能涉及前体细胞的扩增，通过促进其生长，抑制其死亡，并控制其终末分化。因此，N-myc调控机制的表征是我们理解细胞生长和分化过程的关键步骤。在本申请中，我们建议检查在小鼠胚胎发育过程中适当调节N-myc基因表达的要求，以确定负责N-myc限制性表达结构域的分子机制。总的来说，提出的实验构成了一个综合的方法，结合遗传，分子和生化分析，应该提供宝贵的信息，在这个重要的致癌基因的调节机制。

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.