How Substrate Dosage Drives Prion Disease Kinetics

项目摘要 朊病毒病是一种独特的快速，普遍致命的进行性神经退行性疾病的人类和其他 哺乳动物它起源于一种单一的蛋白质，即天然朊病毒蛋白（PrP），它能够在感染后 错误折叠成自我模板化的致命“朊病毒”概念的遗传学和药理学证明 越来越多地确定PrP剂量作为理解的关键，并最终拦截这种致病性 级联。在PrP基因水平改变的小鼠中，较低的PrP水平导致朊病毒感染后存活时间延长 感染，而过量的PrP加速疾病。PrP降低反义寡核苷酸（ASO）现在显示 作为一种潜在的治疗策略。然而，有效的执行将取决于更深层次的 了解PrP水平如何控制朊病毒成核、复制和神经毒性的速率，以及 这种控制可以跨越疾病的时间点、物种和菌株。尽管几乎所有的人类朊病毒疾病 起源于大脑，降低PrP的干预措施尚未在自发性，而不是 接种的朊病毒模型同时，50%的遗传PrP减少所传达的保护程度可以 模型系统之间存在差异;朊病毒复制减慢和神经毒性减慢的相对贡献 在不同物种和朊病毒株中观察到的存活益处仍有待解开。最后，PrP降低 必须在患者来源的人类朊病毒的背景下进行研究，以评估上述学习如何外推到 公共健康利益的菌株。我们将通过评估以下内容来填补这些空白。1)自发反应动力学 朊病毒形成使用一种新的自发性朊病毒疾病的小鼠模型，我们将跟踪自发性朊病毒疾病， 通过一系列分子测量神经元损伤和朊病毒播种活性来研究疾病过程。 通过在不同的时间点给予降低PrP的工具化合物，我们将解开PrP 剂量调节朊病毒形成、扩增、神经毒性和症状进展。2)快速和 慢朊病毒亚型与PrP剂量的函数关系。使用新设计的PrP敲除仓鼠和大鼠 模型，我们将描述相对于疾病发作和终末的病理生物标志物升高的动力学特征 疾病作为PrP表达水平函数在典型快速（仓鼠）和更缓慢进展中 (rat)朊病毒疾病系统。3)PrP降低对人朊病毒的影响。用一系列的小说 在六种不同剂量水平下表达人PrP的“人源化”小鼠系， 对多种临床相关的人朊病毒株敏感，我们将描述病理学、症状 发病和晚期疾病。PrP水平也将通过基因操作在终身基础上变化 如通过出生后，精确定时的干预与PrP降低工具化合物。综上所述各项 研究将阐明PrP在朊病毒疾病模式中对疾病动力学的控制， 建立科学基础，指导未来降低PrP治疗的发展。

PROJECT SUMMARY Prion disease is a uniquely rapid, universally fatal progressive neurodegenerative disease of humans and other mammals. It arises from a single protein, the native prion protein (PrP), which is capable of post-translationally misfolding into a self-templating and deadly “prion.” Genetic and pharmacological proofs of concept increasingly identify PrP dosage as the key to understanding, and ultimately intercepting this pathogenic cascade. In mice with genetically altered PrP levels, lower PrP levels lead to longer survival following prion infection, while excess PrP hastens disease. PrP-lowering antisense oligonucleotides (ASOs) now show promise as a potential therapeutic strategy. However, effective implementation will hinge on a deeper understanding of how PrP level controls the rates of prion nucleation, replication and neurotoxicity, and how this control translates across disease timepoints, species and strains. Though almost all human prion disease originates in the brain, PrP-lowering interventions have not yet been tested in spontaneous, rather than inoculated, prion models. Meanwhile, the magnitude of protection conveyed by 50% genetic PrP reduction can vary between model systems; the relative contributions of slowed prion replication and slowed neurotoxicity to observed survival benefit in different species and prion strains remain to be disentangled. Finally, PrP lowering must be studied in the context of patient-derived human prions, to assess how above learnings extrapolate to strains of public health interest. We will fill these gaps by assessing the following. 1) Kinetics of spontaneous prion formation. Using a new mouse model of spontaneous prion disease, we will track the spontaneously disease process through serial molecular measurements of neuronal damage and prion seeding activity. Through PrP-lowering tool compounds administered at different timepoints, we will disentangle how PrP dosage modulates prion formation, amplification, neurotoxicity and symptomatic progression. 2) Rapid and slow prion subtypes as a function of PrP dosage. Using newly engineered PrP knockout hamster and rat models, we will characterize the kinetics of pathological biomarker rise relative to disease onset and terminal illness as a function of PrP expression level in both canonically rapid (hamster) and more slowly progressive (rat) prion disease systems. 3) Impact of PrP lowering on human prions. Using a series of novel “humanized” mouse lines expressing human PrP at six different dosage levels, that have been shown susceptible to multiple clinically relevant human prion strains, we will characterize time to pathology, symptom onset, and terminal illness. PrP level will be varied on a lifelong basis through genetically manipulation, as well as through postnatal, precisely timed intervention with PrP-lowering tool compounds. Taken together, these studies will illuminate PrP’s control of disease kinetics across a spectrum of prion disease paradigms, while building a scientific foundation to guide future development of PrP-lowering therapeutics.