Elucidating the mechanism and consequences of aberrant cyclin D1 gene expression

摘要 一些基因采取极端措施迫使它们异常表达。例如，细胞周期蛋白D1基因 在血癌外套细胞淋巴瘤中表达的是B细胞淋巴细胞中正常不存在的 (MCL)。MCL是所有B细胞恶性肿瘤中最具侵袭性的，也是一种染色体易位事件， 在疾病发生前，激活细胞周期蛋白D1启动子是启动病变转化的正常 B细胞。一旦表达，转录的细胞周期蛋白D1信息(Pre-mRNAs)将经过进一步的处理 这使得它能够缩短它的3‘非翻译区(3’UTR)，从而增加转录本的半衰期。 细胞周期蛋白D1在MCL中的表达促进了高增殖表型，并增加了遗传性 B细胞的不稳定性和染色体异常。在我们之前的工作中，我们发现了一个新的融合基因 MCL细胞系和患者样本中，细胞周期蛋白D1连接到另一个基因，从而导致截短 3‘非编码区。这个项目的目标是确定驱动细胞缩短的分子机制。 细胞周期蛋白D_1的3‘非翻译区以及细胞周期蛋白D_1引起的染色体易位事件的影响。在这 建议我们将确定在细胞周期蛋白D1的前信使核糖核酸中发现的序列以及蛋白质 参与3‘末端加工对细胞周期蛋白D1在MCL中的表达起着优化作用(目标1)。我们会 也系统地识别由染色体易位事件引起的融合基因，使用第三种方法 世代测序技术，使我们能够获得全长基因转录本(目标2)。虽然 已知的染色体易位在MCL中发生的频率很高，除了 在个别案例研究中的偶然发现，几乎没有努力在一种 全球范围的研究使这类研究具有创新性。此外，我们的研究将确定分子 异常3‘端形成的基础将回答该领域的一个基本问题。这将产生积极的影响 通过建立对致病基因的更好理解，基因在人类细胞中表达，并将使 寻找更有效的检测和治疗疾病的策略。

ABSTRACT Some genes take drastic measures to force their aberrant expression. As an example, the gene cyclin D1 which is not normally present in B-cell lymphocytes is expressed in the blood cancer Mantle Cell Lymphoma (MCL). MCL is the most aggressive of all B-cell malignancies and a chromosomal translocation event, that pre-dates the disease, activates the cyclin D1 promoter is the initiating lesion in the transformation of normal B-cells. Once expressed, the transcribed cyclin D1 message (pre-mRNA) undergoes further processing which enables it to shorten it's 3'untraslated region (3'UTR) thus increasing the half-life of the transcript. The expression of cyclin D1 in MCL facilitates a hyper-proliferative phenotype and increases the genetic instability and chromosomal abnormalities of B-cells. In our prior work we identified a novel fusion gene in MCL cell lines and patient samples where cyclin D1 is joined to another gene thus resulting in a truncated 3'UTR. The goal of this project is to determine the molecular mechanisms that drive the shortening of the 3'UTR of cyclin D1 as well as the effects of the cyclin D1 driven chromosomal translocation events. In this proposal we will determine how the sequences found in the pre-mRNA of cyclin D1 as well as proteins involved in 3'end processing play a role in optimizing the expression of cyclin D1 in MCL (Aim 1). We will also systematically identify fusion genes, which result from chromosomal translocation events, using third generation sequencing technology which allows us to get full length gene transcripts (Aim 2). Although chromosomal translocations are known to occur with a high degree of frequency in MCL, apart from serendipity discovery in individual case studies, little effort has been put into identifying fusion genes on a global scale making this type of research innovative. Furthermore, our study will determine the molecular basis of abnormal 3'end formation will answer a basic question in the field. This will have a positive impact by establishing better understanding of disease causing genes are expressed in human cells and will allow for more effective strategies to detect and treat disease.