Molecular Genetics of Segment Identity

描述（由申请人提供）：本项目的长期目标是了解同源结构域转录因子Hox家族如何在体内调节其靶基因。Hox蛋白是动物发育的重要调节因子。它们也是许多人类疾病的基础。先前的工作表明，这些DNA结合蛋白使用至少两个辅因子，外齿和同胸，以选择正确的靶基因在体内。牙外体和同胸也是同源结构域蛋白，并且也与各种白血病有关。一旦与DNA结合，则认为额外的因子被募集到Hox/外齿/同胸复合体以控制靶基因表达。这些复合物可用于基因激活和基因抑制。 使用果蝇作为实验系统，这里提出的实验部分旨在识别这些额外的因素。其中一些预期是DNA结合蛋白，而另一些预期是共阻遏物或共激活物或具有募集这些转录调节因子的能力的蛋白。一组实验集中在Hox抑制的靶基因Distalless上，旨在测试最近在初步实验中发现的两种蛋白质的作用，这两种蛋白质似乎与Hox/Extradenticle/Homothorax复合物合作抑制转录。第二组实验建议使用生物化学方法来识别并最终表征Hox/Extradenticle/Homothorax复合体用于影响基因调控的因素。第三个目标是解决如何Hox蛋白实现DNA结合特异性的细胞外牙体和Homothorax不能作为辅因子。假设其他蛋白质在这些细胞中充当Hox辅因子，并设计实验来鉴定和测试这些推定的辅因子在体内的功能。

DESCRIPTION (provided by applicant): The long-term goal of this project is to understand how the Hox family of homeodomain transcription factors regulate their target genes in vivo. Hox proteins are critical regulators of animal development. They also underlie many human diseases. Prior work suggests that these DNA binding proteins use at least two cofactors, Extradenticle and Homothorax, to select the correct sets of target genes in vivo. Extradenticle and Homothorax are also homeodomain proteins and are also implicated in various leukemias. Once bound to DNA, additional factors are then thought to be recruited to Hox/Extradenticle/Homothorax complexes to control target gene expression. These complexes can be used for both gene activation and gene repression. Using Drosophila melanogaster as the experimental system, the experiments proposed here are in part aimed at identifying these additional factors. Some of these are expected to be DNA binding proteins whereas others are expected to be co-repressors or co-activators or proteins that have the capacity to recruit these transcriptional regulators. One set of experiments focus on the Hox-repressed target gene Distalless and are aimed at testing the role of two proteins, recently identified in preliminary experiments, that appear to collaborate with Hox/Extradenticle/Homothorax complexes to repress transcription. A second set of experiments propose to use a biochemical approach to identify and ultimately characterize factors used by Hox/Extradenticle/Homothorax complexes to effect gene regulation. A third aim addresses how Hox proteins achieve DNA-binding specificity in cells where Extradenticle and Homothorax are not available to act as cofactors. Other proteins are hypothesized to act as Hox cofactors in these cells, and experiments are designed to identify and test the function of these putative cofactors in vivo.