Mechanisms of neuronal network dysfunction in juvenile neuronal ceroid lipofuscinosis

项目总结 大多数代谢性疾病，包括三分之二的溶酶体储存障碍(LSD)影响大脑。对许多人来说， 包括幼年神经元性蜡样脂褐素沉着症(JNCL)，目前尚不清楚生化缺陷是如何诱导的 中枢神经系统功能障碍。研究主要集中在细胞水平的病理学上，很少有研究。 代谢缺陷是如何扰乱神经元功能回路的。最终，大脑网络的破坏会导致 这些症状，如癫痫发作和神经认知衰退，对患者是毁灭性的。 JNCL是由CLN3双等位基因突变引起的。CLN3蛋白丢失如何扰乱神经功能 不清楚。在前期工作中，我已经证明了JNCL小鼠和人类患者一样，有异常的 脑电图，表明小鼠是电路水平研究的合适模型。关于尸检，JNCL 大脑表现为神经变性和溶酶体储存堆积；尤其是海马体 很脆弱。在我对JNCL小鼠海马区的初步电压敏感染料成像(VSDI)研究中，我 发现了兴奋性的渐进性变化。此外，最近对晚期JNCL的研究表明，突触 小鼠海马体功能障碍。然而，在对晚期疾病的研究中，不可能分析 这些变化是由于CLN3蛋白的原发丢失还是继发于广泛的神经病理。 基因和/或酶替代疗法正在为许多LSD开发。虽然这很令人兴奋，但移动到 在我们知道替代治疗是否能治愈患者之前，基于基因的治疗是有问题的。何时何地 救援蛋白的表达尚不清楚。一个主要的悬而未决的问题是，生化缺陷的纠正 潜在的代谢性疾病将挽救神经元网络的功能，并改善症状。 我的中心假设是，在JNCL中，海马回路的病理是由突触功能障碍引起的 通过CLN3蛋白的丢失。由于发展异常的网络动态，易受攻击的窗口 可能存在单细胞生化纠正不能纠正功能缺陷。我会评估 这是通过：1)在两个JNCL模型中使用VSDI定义电路级病理；2)探索突触和 细胞变化驱动网络变化，以及3)评估CLN3在不同阶段的表达是否被挽救 疾病可以挽救回路和突触动力学。这项工作对今后的研究具有重要的意义 CLN3蛋白的基础科学与JNCL的新疗法。 作为一名医学博士，我热衷于将基础科学发现转化为我的病人的新疗法 患有神经代谢障碍。我的导师埃里克·马什博士，一位内科科学家，神经遗传学家和 电生理学家和溶酶体储存疾病专家贝弗利·戴维森博士致力于他们的职业生涯 为了这个目标。在他们的指导下，我将利用这5年的经验来学习应用我的电生理技能 为大脑研究做准备，并准备成为一名由R01资助的独立翻译研究人员。

PROJECT SUMMARY Most metabolic diseases, including two-thirds of lysosomal storage disorders (LSD) affect the brain. For many, including Juvenile Neuronal Ceroid Lipofuscinosis (JNCL), it is not known how the biochemical defect induces central nervous system dysfunction. Studies have focused on cellular-level pathology, with few investigations of how metabolic defects disrupt functional neuronal circuits. Ultimately, disruption of brain networks leads to the symptoms, such as seizures and neurocognitive regression, that are devastating to patients. JNCL results from biallelic mutations in CLN3. How loss of CLN3 protein disrupts neurologic function is unclear. In preliminary work, I have demonstrated that JNCL mice, like human patients, have abnormal electroencephalograms, suggesting mice are a suitable model for circuit-level studies. On autopsy, JNCL brains show neurodegeneration and lysosomal storage accumulation; the hippocampus is especially vulnerable. In my preliminary voltage-sensitive dye imaging (VSDI) studies of the JNCL mouse hippocampus, I have found progressive changes in excitability. Also, recent studies of late-stage JNCL show synaptic dysfunction in the mouse hippocampus. However, in studies of late-stage disease it is impossible to parse which changes are due to the primary loss of CLN3 protein or secondary to widespread neuropathology. Gene and/or enzyme replacement therapy is being developed for many LSDs. While this is exciting, moving to gene-based treatment before we know if replacement will fix the patients is problematic. Where and when to rescue protein expression is unclear. A major unanswered question is if correction of the biochemical defect underlying a metabolic disease will rescue the function of neuronal networks and improve symptoms. My central hypothesis is that in JNCL, hippocampal circuit pathology arises from synaptic dysfunction induced by loss of CLN3 protein. Because of the development of abnormal network dynamics, a vulnerable window may exist beyond which correction of single cell biochemistry will not correct functional defects. I will evaluate this by: 1) defining circuit level pathology using VSDI in two JNCL models; 2) exploring the synaptic and cellular changes driving network changes, and 3) assessing if rescue of CLN3 expression at different stages of disease can rescue circuit and synaptic dynamics. This work has important implications for future studies of the basic science of the CLN3 protein and novel therapies for JNCL. As an MD/PhD, I am passionate about translating basic science discoveries into new therapies for my patients with neurometabolic disorders. My mentors Dr. Eric Marsh, a physician-scientist neurogeneticist and electrophysiologist, and Dr. Beverly Davidson, a lysosomal storage disease expert, have devoted their careers to this goal. Under their guidance, I will use this 5-year experience to learn to apply my electrophysiology skills to studies of the brain and to prepare for a career as an independent R01-funded translational researcher.