Defining the components of olfactory singular expression

摘要 单等位基因表达是一种不寻常的基因调控形式，通常与 决定细胞类型的基因。嗅觉系统表现出一种有趣的形式， 随机单等位基因表达。老鼠鼻子里的每个感觉神经元只表达一种 超过2000种气味受体（OR）等位基因。目前的OR基因选择模型 涉及分布的增强子在染色体间聚集成单个活性超级增强子， 增强子，由转录因子Lhx 2和Ebf的共结合驱动。这个超级增强剂 复合物吸引所有OR启动子。这种组装如何选择单个OR基因启动子， 转录未知。理解这个过程需要更好地理解 OR基因启动子在这种超级增强子复合物的背景下起作用。 与OR增强子一样，启动子含有Lhx 2和Lhx 3的同源域（HD）结合位点。 Ebf转录因子的Olf 1/Ebf（O/E）结合位点。这些位点如何在OR启动子中起作用 参与选择机制尚不明确。我们提出了一系列遗传实验， 定义HD和O/E位点在OR启动子功能中的作用。为此，我们将有针对性地研究 OR转基因位于OR簇之外，提供了一个独特的工具来研究遗传和 表观遗传特征是OR表达所必需的。此外，我们还提出了一种联合遗传学 和生物化学方法来确定OR选择机制的分子组成， 原子核总的来说，这些方法试图首次阐明 OR单等位基因表达的基础。我们的研究结果将阐明 控制着哺乳动物的基因表达

Abstract Monoallelic expression is an unusual form of gene regulation that is often associated with genes that determine cell-type identity. The olfactory system exhibits an intriguing form of random monoallelic expression. Each sensory neuron in the mouse nose expresses only one out of over 2000 odorant receptor (OR) alleles. The current model for OR gene selection involves the interchromosomal aggregation of distributed enhancers into a single active super- enhancer, driven by the co-binding of transcription factors Lhx2 and Ebf. This super-enhancer complex attracts all OR promoters. How this assembly selects a single OR gene promoter for transcription is unknown. Understanding this process requires a better understanding of how OR gene promoters function in the context of this super-enhancer complex. Like OR enhancers, the promoters contain homeodomain (HD) binding sites for Lhx2 and Olf1/Ebf (O/E) binding sites for Ebf transcription factors. How these sites act in OR promoters to engage the choice mechanism is not clear. We propose a set of genetic experiments to define the role of HD and O/E sites in OR promoter function. To do this we will study targeted OR transgenes that lie outside of OR clusters, providing a unique tool to study what genetic and epigenetic features are required for OR expression. Moreover, we propose a combined genetic and biochemical approach to identify the molecular components of the OR choice mechanism in the nucleus. Taken together, these approaches seek to elucidate for the first time the molecular basis for OR monoallelic expression. Our findings will shed light on fundamental mechanisms that govern gene expression in mammals.