Molecular Mechanisms of Prion Protein Amyloid Formation

朊病毒蛋白淀粉样蛋白形成的分子机制

• 批准号: 7964765
• 负责人: SUZETTE Alise PRIOLA
• 金额: $ 82.43万
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7964765
• 关键词: Amino Acid Motifs; Amino Acids; Amyloid; Amyloidosis; Biological Models; Bovine Spongiform Encephalopathy; Brain; Cell-Free System; Chronic Wasting Disease; Creutzfeldt-Jakob Syndrome; Data; Deer; Deposition; Diffuse; Disease; Endopeptidase K; Equine mule; Germ-Line Mutation; Great Britain; Human; In Vitro; Induced Mutation; Infection; Infectious Agent; Inherited; Modeling; Molecular; Mus; Mutation; Nature; Neurodegenerative Disorders; Pathogenesis; Pathology; Pathway interactions; Peptides; PrP; PrP amyloid; PrP gene; PrPC Proteins; PrPSc Proteins; Predisposition; Prion Diseases; Prions; Process; Production; Property; Proteins; Resistance; Scrapie; Sheep; Structure; System; Therapeutic; amyloid formation; expectation; human PrP; in vivo Model; interest

Transmissible spongiform encephalopathies (TSE) are a group of rare neurodegenerative diseases which include Creutzfeldt-Jakob disease (CJD) in humans, scrapie in sheep, bovine spongiform encephalopathy (BSE) and chronic wasting disease (CWD) in mule deer and elk. TSE infectivity can cross species barriers. The fact that BSE has infected humans in Great Britain and concerns that CWD may act similarly in the US underscores the importance of understanding TSE pathogenesis and developing effective anti-TSE therapeutics. The precise nature of the infectious agent of the TSE diseases is unknown. Susceptibility to infection can be influenced by amino acid homology between a normal host protein (PrP-sen) and the abnormal proteinase K-resistant form of this protein, PrP-res. Formation of PrP-res is closely associated with infectivity and PrP-res has been hypothesized to be the infectious agent in the TSE diseases. However, PrP-res can be deposited in the brain as either diffuse, amyloid negative deposits or as dense, amyloid positive deposits. Amyloid forms of TSE appear to be less transmissible than non-amyloid forms, suggesting that there is a fundamental difference in how they trigger disease. Furthermore, it is unclear whether or not TSE diseases where PrP-res is deposited primarily as amyloid follow the same pathogenic processes as TSE diseases where PrP-res is deposited as non-amyloid forms. We are interested in understanding the molecular mechanisms underlying PrP amyloid formation and have begun to approach this issue using both in vitro and in vivo model systems. This project focuses on: 1) understanding the pathways of PrP amyloid formation and, 2) studying how mutations in PrP influence PrP-res amyloid formation in familial forms of TSE disease. In 2009, we used PrP peptides in a cell-free system of fibrillization to examine how different regions of the PrP molecule may influence PrP amyloid formation. We have also infected mice that express human PrP-sen without the GPI anchor with different types of human TSE. Our expectation is that, if these mice develop PrP amyloid, we can utilize them as an in vivo model system for human amyloid disease. Hereditary forms of TSE disease are associated with mutations within the PrP gene. One of these mutations is the insertion of extra copies of an eight amino acid motif (octapeptide repeat) into PrP. We have used an in vitro fibrillization model of this hereditary mutation to study how the repeat region influences the formation of both PrP-res and PrP amyloid. Last year, we demonstrated that environmental conditions could change the mechanism of fibril formation which in turn altered the ultrastructural properties of the amyloid. In 2009, we have gathered data suggesting that the octapeptide repeat region can significantly influence the final structure of both PrP-res and PrP amyloid. The structural influence of the octapeptide repeat region appears to be strain specific and thus may help to explain the different pathologies associated with different types of TSE infectivity.

可传播的海绵状脑病（TSE）是一组罕见的神经退行性疾病，包括人类中的克鲁特兹菲尔特 - 贾科布病（CJD），绵羊的scrapie，牛海绵性脑病（BSE）和M子和Elk的牛皮脑病（BSE）和慢性浪费疾病（CWD）。 TSE感染性可以跨越物种障碍。 BSE在英国感染了人类，并且担心CWD可能在美国采取类似的作用强调了理解TSE发病机理和发展有效的抗TSE治疗剂的重要性。 TSE疾病的传染药的确切性质尚不清楚。对感染的敏感性可能会受到正常宿主蛋白（PRP-SEN）和该蛋白PRP-RES异常蛋白酶K耐药形式之间氨基酸同源性的影响。 PRP-RES的形成与感染性密切相关，PRP-RES已被认为是TSE疾病中的感染剂。 但是，PRP-RES可以作为扩散，淀粉样蛋白负沉积物或淀粉样蛋白阳性沉积物作为弥漫性，淀粉样蛋白负沉积物。 TSE的淀粉样蛋白形式似乎不如非淀粉样形式传播，这表明它们在触发疾病的方式上存在根本差异。 此外，目前尚不清楚PRP-RES主要沉积的TSE疾病是否主要是淀粉样蛋白遵循与TSE疾病相同的致病过程，其中PRP-RES被沉积为非淀粉样蛋白形式。 我们有兴趣了解PRP淀粉样蛋白形成的分子机制，并开始使用体外和体内模型系统来解决此问题。 该项目的重点是：1）了解PRP淀粉样蛋白形成的途径，以及2）研究PRP中的突变如何影响PRP-RES淀粉样蛋白形成TSE疾病的形式。 在2009年，我们在无细胞的原纤维系统中使用了PRP肽来检查PRP分子的不同区域如何影响PRP淀粉样蛋白的形成。 我们还感染了无带有不同类型的人类TSE的GPI锚固的人类PRP-SEN的小鼠。 我们的期望是，如果这些小鼠发展为PRP淀粉样蛋白，我们可以将它们用作人淀粉样蛋白疾病的体内模型系统。 TSE疾病的遗传形式与PRP基因内的突变有关。 这些突变之一是将八个氨基酸基序（八肽重复）的额外副本插入到PRP中。 我们已经使用了这种遗传突变的体外原纤维化模型来研究重复区域如何影响PRP-RES和PRP淀粉样蛋白的形成。 去年，我们证明了环境条件可能会改变原纤维形成的机制，从而改变了淀粉样蛋白的超微结构特性。 在2009年，我们收集了数据，表明八肽重复区域可以显着影响PRP-RES和PRP淀粉样蛋白的最终结构。 八肽重复区域的结构影响似乎是特异性的，因此可能有助于解释与不同类型的TSE感染性相关的不同病理。