Role of Prion Protein in Manganese Neurotoxicity

朊病毒蛋白在锰神经毒性中的作用

基本信息

批准号：
8494047
负责人：
Anumantha Gounder Kanthasamy
金额：
$ 67.27万
依托单位：
IOWA STATE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-07-09 至 2015-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8494047
关键词：
Address Affinity Animal Model Animals Antioxidants Apoptosis Apoptotic Attenuated Basal Ganglia Binding Binding Proteins Binding Sites Biological Assay Blood Bovine Spongiform Encephalopathy Brain Brain Diseases Brain region Cell Adhesion Cell Adhesion Molecules Cell Culture Techniques Cell Death Cell physiology Cells Chronic Chronic Wasting Disease Copper Data Deer Digestion Disease Divalent Cations Dose Endopeptidase K Environmental Exposure Etiology Exposure to Figs - dietary Genetic Transcription Heat shock proteins Homeostasis Human Infection Investigation Knockout Mice Link Mammals Manganese Metalloproteins Metals Mitochondria Modeling Mus Nerve Degeneration Neurodegenerative Disorders Neurologic Neurons Organism Oxidative Stress Pathogenesis Pathologic Processes Peptide Hydrolases Play PrP PrPSc Proteins Prion Diseases Prions Protein Region Proteins Reporting Research Resistance Role Scrapie Seeds Severities Signal Transduction Slice Staging Stress Structure Testing Time Transducers Transgenic Animals Transgenic Mice Transgenic Model Transition Elements Up-Regulation Zinc conformational conversion divalent metal insight mitochondrial dysfunction mouse model mutant neurochemistry neurotoxicity novel overexpression oxidative damage particle protein aggregation protein function protein misfolding cyclic amplification public health relevance response stress protein

项目摘要

DESCRIPTION (provided by applicant): Environmental exposure to transition metals is linked to pathological processes of various neurodegenerative conditions since metal neurotoxicity often augments key degenerative changes including ionic imbalance, oxidative stress and protein aggregation. Several metal binding proteins regulate intracellular metal homeostasis and thereby maintain normal cellular function. Emerging evidence indicates that prion proteins are metal binding proteins that can efficiently bind to certain divalent cations including copper and manganese at the octapeptide repeat regions of the protein. Therefore, dysregulation of metal homeostasis has been suggested to play a role in the pathogenesis of prion diseases. Recent observations of elevated manganese (Mn) levels in the brain and blood of humans and animals afflicted with prion diseases suggest that manganese neurotoxicity may play a role in the etiology of prion diseases. Recently, we demonstrated that normal prion protein effectively attenuates manganese transport into neuronal cells and protects against manganese-induced oxidative stress, mitochondrial dysfunction, cellular antioxidant depletion, and apoptosis. While investigating these mechanisms, we unexpectedly found that manganese treatment upregulates cellular prion levels independent of transcription. Furthermore, we found manganese increases stability, suggesting that prion protein may promote the conversion of normal prion protein (PrPC) to the pathological form of prion (PrPSc), which results in the loss of normal prion protein's protective function against manganese neurotoxicity. Thus, the central hypothesis of this proposal is that manganese binds to the octapeptide (PHGGGWGQ) domain of cellular prion protein to increase the stability and accumulation of the protein. Manganese-induced stabilization of prion protein accelerates conformational conversion of PrPC to proteinase-resistant prion protein (PrPSc) aggregates and thereby induces neurotoxicity. This novel hypothesis will be tested through a systematic investigation of the following specific aims: i) to determine whether chronic exposure to manganese increases prion protein accumulation in animal models, ii) to determine the role of octapeptide repeat sequences in the manganese-induced stabilization of prion protein, iii) to determine whether chronic manganese exposure accelerates the accumulation and aggregation of the scrapie form of prion protein (PrPSc) and causes increased neuronal damage in a mouse model of prion disease, iv) to compare the effect of manganese on the accumulation and aggregation of PrPSc and on neuronal damage in mouse scrapie-infected prion overexpressing and octapeptide deletion transgenic animals (Tg20 and TgPrPDOR transgenic mice). Together, results from the proposed studies will not only provide new insights into the role of prion protein in manganese neurotoxicity but also will advance understanding of the role of metals in the pathogenesis of prion diseases.

描述（由申请人提供）：过渡金属的环境暴露与各种神经退行性疾病的病理过程有关，因为金属神经毒性通常会加剧关键的退行性变化，包括离子失衡、氧化应激和蛋白质聚集。几种金属结合蛋白调节细胞内金属稳态，从而维持正常的细胞功能。新的证据表明，朊病毒蛋白是金属结合蛋白，可以有效地与蛋白质八肽重复区域的某些二价阳离子（包括铜和锰）结合。因此，金属稳态失调被认为在朊病毒疾病的发病机制中发挥作用。最近对患有朊病毒疾病的人类和动物的大脑和血液中锰（Mn）水平升高的观察表明，锰的神经毒性可能在朊病毒疾病的病因学中发挥作用。最近，我们证明正常的朊病毒蛋白可有效减弱锰向神经元细胞的转运，并防止锰诱导的氧化应激、线粒体功能障碍、细胞抗氧化剂耗竭和细胞凋亡。在研究这些机制时，我们意外地发现锰处理可上调细胞朊病毒水平，而与转录无关。此外，我们发现锰增加了稳定性，表明朊病毒蛋白可能促进正常朊病毒蛋白（PrPC）转化为病理形式的朊病毒（PrPSc），从而导致正常朊病毒蛋白丧失针对锰神经毒性的保护功能。因此，该提议的中心假设是锰与细胞朊病毒蛋白的八肽（PHGGGWGQ）结构域结合，以增加蛋白质的稳定性和积累。锰诱导的朊病毒蛋白稳定化加速了 PrPC 向耐蛋白酶朊病毒蛋白 (PrPSc) 聚集体的构象转化，从而诱导神经毒性。这一新假设将通过对以下具体目标的系统研究进行检验：i）确定长期接触锰是否会增加动物模型中朊病毒蛋白的积累，ii）确定八肽重复序列在锰诱导的朊病毒蛋白稳定中的作用朊病毒蛋白，iii) 确定长期接触锰是否会加速朊病毒蛋白 (PrPSc) 的瘙痒病形式的积累和聚集，并导致朊病毒病小鼠模型的神经元损伤增加，iv)比较锰对感染瘙痒病的朊病毒过表达和八肽缺失转基因动物（Tg20 和 TgPrPDOR 转基因小鼠）中 PrPSc 积累和聚集以及神经元损伤的影响。总之，拟议研究的结果不仅将为朊病毒蛋白在锰神经毒性中的作用提供新的见解，而且还将促进对金属在朊病毒疾病发病机制中作用的理解。