Long noncoding RNA expressing genomic element that control antibody diversification and chromosomal integrity in B cells

项目摘要/摘要 越来越明显的是，哺乳动物的大多数基因组都有可能 表达非编码RNA(NcRNAs)。然而，监管的功能和机制(S) 这些ncRNA才刚刚开始被探索。生物学家面临的一个挑战是 对这些ncRNA的检测，通常倾向于在转录上受到严密和快速的控制 降级了。我们最近发现了一个长的非编码(Lnc)rna表达位点，称为 LncRNA-CSR，调节B细胞免疫球蛋白重链(IgH)基因的DNA重排 细胞。使用缺乏LncRNA处理/降解活性的小鼠模型系统以及 与高通量基因组学、生物信息学和各种基于芯片序列的 实验中，我们能够预测lncRNA-CSR的长程转录增强功能 轨迹。在本申请中，我们继续将研究重点放在lncRNA-CSR的功能上 和另外三个新的lncRNA表达基因座，我们认为它们在协调DNA方面发挥了作用 生发中心常驻B细胞中的重排事件。B淋巴细胞具有独特的能力 对它们的基因组进行程序性体细胞突变(在免疫球蛋白基因座)以 产生我们的免疫系统所需的抗体的多样性，以对抗过剩的 我们可能会遇到抗原，这一过程被称为抗体多样化。然而，作为抵押品 从这种非常不寻常和有用的能力中出现的损害进行有益的躯体 突变事件是指B细胞意外地以很低的频率突变其基因组的能力 在各种不合适的地方。这些意外突变是各种B细胞的原因 恶性肿瘤，尤其是那些起源于生发中心的B细胞。有趣的是， B细胞的致癌易位发生在分化转录区域--即启动子 以及增强子--存在于超级增强子簇的拓扑域内。我们假定 LncRNA-CSR负责连接远距离调控元件(即启动子和 增强子)，以促进基因组组织、转录 控制受调控的基因，并最终促进抗体多样化机制，而不是 诱发癌症导致DNA改变。

PROJECT SUMMARY/ ABSTRACT It is becoming increasingly evident that the majority of the mammalian genome has the potential to express non-coding RNAs (ncRNAs). However, the functionality and mechanism(s) of regulation of these ncRNAs are just beginning to be explored. One challenge that biologists encounter is the detection of these ncRNAs, which often tend to be transcriptionally tightly controlled and rapidly degraded. We have recently identified a long noncoding (lnc) RNA expressing locus, known as lncRNA-CSR, that regulates DNA rearrangments in the Immunoglobulin heavy chain (IgH) locus of B cells. Using mouse model systems that lack lncRNA processing/degradation activity along with a combination with high throughput genomics, bioinformatics, and various ChIP-seq based experiments, we are able to predict long-range transcription enhancer function of the lncRNA-CSR locus. In this application, we continue to focus our investigation on the functionality of lncRNA-CSR and three other novel lncRNA expressing loci, that we propose to have a role in orchestrating DNA rearrangment events in germinal center resident B cells. B lymphocytes have the unique ability to undergo programmed somatic mutagenesis of their genomes (at immunoglobulin gene loci) to generate the diversity of antibodies required by our immune system to combat the plethora of antigens we might encounter, a process known as antibody diversification. However, as collateral damage emerging from this very unusual and useful ability to undertake beneficial somatic mutagenesis events is the ability of B cells accidently to mutate their genome at a very low frequency at various inappropriate locations. These accidental mutations are the cause of various B cell malignancies, particularly those that evolve from germinal center derived B cells. Interestingly, cancer-causing translocations in B cells occur at regions of divergent transcription—that is, promoters and enhancers—which exist inside topological domains of superenhancer clusters. We postulate that lncRNA-CSR is responsible for tethering long distant regulatory elements (i.e, promoters and enhancers) in the IgH locus superenhancer cluster to facilitate genome organization, transcription control of regulated genes, and, ultimately, to promote antibody diversification mechanisms without inducing cancer causing DNA alterations.