Promoter-Enhancer Interactions at the Drosophila Bithorax Complex

描述（由申请人提供）：在过去的十年中，许多生物的基因组已经完全测序。两个惊人的观察结果是：高等真核生物的基因组所包含的基因比最初预测的要少得多；大多数基因组DNA迄今为止还没有公认的功能。因此，这些物种急剧增加的生物复杂性必须严重依赖于它们发育过程中基因网络的非常严格的定向表达。这种复杂的调控很大程度上依赖于非蛋白质编码基因间区未被表征的功能。一个核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。最近一项令人兴奋的进展是研究人员发现了一种新的DNA序列，它直接调节启动子-增强子的相互作用。本文提出的研究将通过转基因和分子实验的方法来具体探讨这种新发现的顺式调控元件在体内的功能作用。

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.