Biogenesis of Small Ribonucleoproteins

描述(申请人提供)：小核糖核蛋白(RNPs)是所有真核细胞的基本成分。作为剪接体的核心元件，小的RNPs是信使前RNA剪接所必需的。剪接的基本机制已经被很好地理解，然而，执行这一过程的小核(Sn)RNPs的生物发生相对不清楚。这项建议的长期目标是了解支配SNRNPs生物发生和亚细胞定位的分子机制。简而言之，我们试图揭示SNRNPs被包装、运输和运送到其行动地点的过程。在SnRNA转录本的核输出之后，SnRNP生物发生的初始阶段开始于细胞质。组装成稳定的颗粒被认为是由运动神经元存活(SMN)蛋白复合体和精氨酸甲基转移酶5(PRMT5)复合体共同介导的。随后，这些小的RNP被输入回细胞核。Sm类小RNPs组装缺陷与一种称为脊髓性肌萎缩症(SMA)的疾病有关。SMA患者通常在儿童早期死亡。虽然在患者来源的细胞中SnRNP的生物发生受到影响，但SMA表型的潜在原因尚不清楚。其他SNRNP生物发生基因的突变可能表现为SMA。因此，详细了解SnRNP的代谢不仅对RNA加工的研究至关重要，而且对开发神经肌肉疾病的治疗方法也很重要。为了深入了解这些过程，我们开发了一个果蝇模型系统。该建议的具体目的是：(1)表征SMN复合体在SnRNP生物发生和神经肌肉发育中的功能；(2)了解SnRNA转运体phax在神经肌肉系统发育中所起的作用，并分析phax和SMN突变对SnRNP功能的影响；(3)研究PRMT5复合体在一类潜在的新的Sm-RNPs生物发生中的活性。摘要：脊髓性肌萎缩症(SMA)是一种常见的遗传性疾病，发病于幼儿；他们中的大多数人在两岁之前死亡。导致这种疾病的基因已经确定，但该基因在细胞中如何发挥作用的潜在基础尚不清楚。为了最终开发出一种治疗方法，我们首先需要了解疾病基因及其伴侣基因的正常功能(S)。

DESCRIPTION (provided by applicant): Small ribonucleoproteins (RNPs) are essential components of all eukaryotic cells. As the core elements of the spliceosome, small RNPs are required for pre-messenger RNA splicing. The basic mechanics of splicing are fairly well-understood, however, the biogenesis of the small nuclear (sn)RNPs that carry out this process is relatively unclear. The long-term goal of this proposal is to understand the molecular mechanisms that govern the biogenesis and subcellular localization of snRNPs. In short, we seek to uncover the process by which snRNPs are packaged, transported and delivered to their sites of action. The initial phases of snRNP biogenesis begin in the cytoplasm, following nuclear export of the snRNA transcript. Assembly into stable particles is thought to be mediated by the Survival of Motor Neurons (SMN) protein complex in collaboration with the Protein Arginine Methyltransferase 5 (PRMT5) complex. Subsequently, these small RNPs are imported back into the nucleus. Defects in the assembly of Sm-class small RNPs are associated with a disorder called Spinal Muscular Atrophy (SMA). Patients with SMA typically die in early childhood. Although snRNP biogenesis is compromised in patient-derived cells, the underlying cause of the SMA phenotype is not understood. Mutations in other snRNP biogenesis genes may phenocopy SMA. Thus a detailed understanding of snRNP metabolism is essential not only to the study of RNA processing, but will also be important in developing treatments for neuromuscular disease. To gain insight into these processes, we have developed a Drosophila model system. Specific Aims of this proposal are: (1) to characterize the function of the SMN complex in snRNP biogenesis and neuromuscular development, (2) to understand the role played by the snRNA transporter, PHAX, in development of the neuromuscular system and to assay the consequences of mutations in phax and smn on snRNP function, and (3) to investigate the activity of the PRMT5 complex in the biogenesis of a potentially novel class of Sm-RNPs. Lay Summary: Spinal Muscular Atrophy (SMA) is a common genetic disease that strikes young children; most of them die before reaching the age of two years. The gene responsible for this disease has been identified, but the underlying basis for how the gene functions in the cell is not known. To ultimately develop a treatment, we first need to understand the normal function(s) of the disease gene and its partner genes.