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

最近的研究提供了大量的证据表明，基因组不仅由线性的 它被折叠成精细的模式，允许基因组之间的相互作用， 大基因组距离分离的元件。的精确折叠和拓扑谱 基因组仍有待确定。最近的研究提供了对3D架构的深入了解， 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 组织成多个隔间，其特征是成束的循环，与 多环亚室（MLS）模型。我们现在面临的问题是， 如MLS模型所提出的，整个基因组被折叠。为了解决这个问题，我们最近 采用甲醛交联方法，允许识别全基因组网络 前B细胞中相互作用的基因组元件。我们的初步数据表明前B细胞基因组 事实上，如MLS模型所预测的那样，被组织成由连接器连接的环簇。 在此，我们建议继续进行这些研究。我们将对个人进行深入分析， 隔室，并检查它们是如何组织的，以及它们如何与B系特定的程序， 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 桥接因子将从生物化学和功能的角度被鉴定和表征。 最后，我们建议，以确定有丝分裂染色体的结构，在前原B和原B细胞。的 总的目标是破译由前原B形成的构象和轨迹谱 和前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.