The 3D-Structures of the Pre-Pro-B and Pro-B Cell Genomes

最近的研究提供了大量证据表明，基因组不仅由线性的 结构，而是折叠成精细的模式，允许基因组之间的相互作用 由很大的基因组距离分开的元素。的精确折叠和拓扑谱 基因组还有待确定。最近的研究提供了对3D架构的洞察 免疫球蛋白重链(IgH)和β-珠蛋白基因座。这些数据表明，这些基因座是 被组织到多个隔间中，这些隔间的特征是环路捆绑，与 多环小班(MLS)模型。我们现在面临的问题是， 按照MLS模型的建议，整个基因组被折叠。为了解决这个问题，我们最近 使用甲醛交联法，允许识别全基因组网络 原B细胞中相互作用的基因组成分。我们的初步数据表明，前B细胞基因组 实际上被组织成由链接器连接的环路集群，正如MLS模型所预测的那样。 在这里，我们建议继续进行这些研究。我们将对个人进行深入的分析 并检查它们是如何组织的，以及它们与B血统特定计划的关系 基因表达。我们将识别和描述染色体内的相互作用。绝缘子和 将从生化和功能的角度确定和表征桥梁因素。 最后，我们建议确定前-前-B和前-B细胞中有丝分裂染色体的结构。这个 总体目标将是破译前PRO-B形成的构象和轨迹的光谱 以及前B细胞染色质纤维以及染色质结构与功能的关系。

Recent studies have provided substantial evidence that the genome consists not merely of linear structures but rather it is folded into elaborate patterns that permits interactions between genomic elements separated by large genomic distances. The precise folding and the spectrum of topologies of the genome remain to be determined. Recent studies have provided insight into the 3D-architectures of the immunoglobulin heavy chain (Igh) and ¿-globin loci. These data have revealed that these loci are organized into multiple compartments that are characterized by bundles of loops, consistent with the Multiple-Loop-Subcompartment (MLS) Model. We are now faced with the question as to whether the entire genome is folded as proposed by the MLS model. To address this question, we have recently employed a formaldehyde cross-linking approach that permits the identification of a genome-wide network of interacting genomic elements in pro-B cells. Our preliminary data indicates that the pro-B cell genome indeed is organized into clusters of loops that are connected by linkers as predicted by the MLS model. Here we would propose to continue these studies. We would perform an in depth analysis of individual compartments and examine how they are organized and how they relate to B-lineage specific programs of gene expression. We would identify and characterize intra-chromosomal interactions. Insulators and bridging factors would be identified and characterized both from a biochemical and functional perspective. Finally, we propose to determine the structure of mitotic chromosomes in pre-pro-B and pro-B cells. The overall goal would be to decipher the spectrum of conformations and trajectories formed by the pre-pro-B and pro-B cell chromatin fibers and how chromatin structure relates to function.