Spinal muscular atrophy therapy using recombinant SMN proteins

描述（由申请人提供）：脊髓性肌萎缩症（SMA）是一种运动神经元神经退行性疾病，由运动神经元存活基因（SMN 1）缺失或突变引起。SMN 1编码运动神经元存活（SMN）蛋白，该蛋白对小核核糖核蛋白颗粒的生物发生很重要，而小核核糖核蛋白颗粒对前体mRNA剪接很重要，但SMA发病机制中涉及的剪接靶点仍不清楚。人类含有第二个部分功能性SMN 2，与SMN 1相比，其外显子7中含有一个核苷酸差异，导致大多数SMN 2转录物和截短的SMN蛋白中外显子7跳跃。从SMN 2表达有限量的功能性全长SMN蛋白，但其通常不能补偿SMN 1的损失。SMN蛋白的丢失会导致肌无力、呼吸窘迫，严重时会导致死亡。SMA的发生频率为6，000至10，000例活产婴儿中的1例，是美国婴儿死亡的主要遗传原因。目前没有治疗方法 或预防疾病，尽管已经广泛研究了许多方法作为潜在的治疗方法。这些方法包括基因治疗以递送SMN 1基因，以及使用反义寡核苷酸或小分子剪接调节SMN 2以增加全长SMN蛋白的表达。在这个项目中，我们提出了一种新的方法来弥补损失的SMN使用重组SMN蛋白缀合到细胞穿透肽（CPP）。CPP是短的（10-30个氨基酸长度）和高度带正电荷的肽，其可以将其共价结合的分子货物（包括DNA、RNA、肽和蛋白质）带入几乎所有细胞类型。在本提案中，我们将评估使用CPP-SMN偶联物进行SMA治疗的可能性。

DESCRIPTION (provided by applicant): Spinal muscular atrophy (SMA) is a neurodegenerative disease of the motor neuron that is caused by deletion or mutation of the survival motor neuron gene (SMN1). SMN1 encodes the survival motor neuron (SMN) protein that is important for the biogenesis of small nuclear ribonucleoprotein particles that are important for pre-mRNA splicing, but the splicing target involved in SMA pathogenesis remains unclear. Humans contain a second and partially functional SMN2, which contains one nucleotide difference in exon 7 compared to SMN1, leading to the skipping of exon 7 in most SMN2 transcripts and truncated SMN proteins. Limited amount of functional full-length SMN protein is expressed from SMN2 but it typically cannot compensate for the loss of SMN1. The loss of SMN protein causes debilitating muscle weakness, respiratory distress, and death in severe cases. SMA occurs at a frequency of one in 6,000 to one in 10,000 live births and it is the leading genetic cause of infant mortality in the United States. There is currently no treatment or prevention of the disease, although a number of approaches have been extensively researched as potential therapeutics. These approaches include gene therapy to deliver the SMN1 gene, and splicing modulation of SMN2 using anti-sense oligo or small molecules to increase the expression of full-length SMN proteins. In this project, we propose a new approach to compensate for the loss of SMN using recombinant SMN protein conjugated to a cell penetrating peptide (CPP). CPP are short (10-30 amino acids in length) and highly positively charged peptides that can bring its covalently conjugated molecular cargos (including DNA, RNA, peptide, and protein) into almost all cell types. In this proposal, we will evaluate the possibility of using CPP-SMN conjugate for SMA therapy.