Promoter-Enhancer Interactions at the Drosophila Bithorax Complex

描述(申请人提供)：在过去的十年里，许多生物的基因组已经完成了测序。两个引人注目的发现是，高等真核生物的基因组包含的基因比最初预测的要少得多，而且到目前为止，大多数基因组DNA还没有被识别的功能。因此，这些物种大大增加的生物学复杂性必须严重依赖于它们发育过程中非常紧密地定向表达的基因网络。这种复杂的调控在很大程度上依赖于非蛋白质编码基因间区的未知功能。一个中心问题是在胚胎发育过程中增强子被招募到特定基因启动子的分子机制。一个令人兴奋的最新进展是研究人员发现了一个新的DNA序列，它直接调节启动子-增强子之间的相互作用。这里提出的研究将通过转基因和分子实验的方法专门研究这种新表征的顺式调节元件在体内的功能作用。 调节果蝇双胸复合体(BX-C)的同源同源异型(HOX)基因表达将是这一应用的重点。来自BX-C的三个编码蛋白的HOX基因的正确时空表达对于控制胚胎前后轴上的发育细胞命运至关重要。BX-C也为基因间非编码DNA在基因表达调控中的功能提供了一些最好的当前证据。提供这种精细控制的调控区域分散在定义BX-C的150 kb DNA中。总的科学目标将是阐明这些调节区实现对整个BX-C基因表达的协调控制的分子机制。主要的焦点将是定义控制BX-C中特定启动子-增强子相互作用的调控机制。这些拟议的研究将为我们理解基因组如何利用表观遗传和顺式调控机制提供对多细胞生物体发育至关重要的精确基因表达模式提供重大进展。此外，考虑到HOX基因复合体在进化过程中的显著保守性，这些发现将为所有进化顺序的发育调控提供广泛的见解。因此，这些研究将对我们理解一些与胚胎发育过程中HOX基因的错误表达有关的人类发育缺陷产生相当大的影响。

DESCRIPTION (provided by applicant): In the past decade, the genomes of many organisms have been completely sequenced. Two striking observations are that the genomes of higher eukaryotes contain significantly fewer genes than originally predicted, and that most of the genomic DNA has, as yet, no recognized function. The vastly increased biological complexity of these species must therefore be critically dependent on very tightly directed expression of gene networks during their development. Much of this complex regulation depends upon uncharacterized functions of non-protein coding intergenic regions. A central question is the molecular mechanism by which enhancers are recruited to specific gene promoters during embryonic development. An exciting recent advance is the investigators' identification of a novel DNA sequence which directly regulates promoter-enhancer interactions. The studies proposed here will specifically address the in vivo functional role of this newly characterized cis-regulatory element through transgenic and molecular experimental approaches. Regulation of homeotic (Hox) gene expression from the bithorax complex (BX-C) in Drosophila melanogaster will be the focus of this application. The correct spatial and temporal expression of the three protein-coding Hox genes from the BX-C is essential for the control of developmental cell fate along the anterior-posterior axis of the embryo. The BX-C also provides some of the best current evidence for the function of intergenic, non-coding DNA in regulation of gene expression. The regulatory regions providing this exquisite control are dispersed throughout the 150 kb of DNA that defines the BX-C. The overall scientific goal will be to elucidate the molecular mechanisms by which these regulatory regions achieve coordinated control of gene expression across the entire BX-C. The major focus will be to define regulatory mechanisms that control specific promoter-enhancer interactions in the BX-C. The proposed studies will provide major advances in our understanding of how the genome utilizes epigenetic and cis-regulatory mechanisms to provide the precise gene expression patterns critical to development in multicellular organisms. Further, given the remarkable conservation of Hox gene complexes across evolution, the findings will provide broad insights into developmental regulation across all evolutionary orders. Consequently, these studies will have a considerable impact on our comprehension of a number of human developmental defects associated with misexpression of Hox genes during embryonic development.