Amyloid ion channels to design therapeutics for neurodegenerative diseases

描述（由申请人提供）：蛋白质构象疾病，包括神经退行性疾病（阿尔茨海默病和帕金森病）、II型糖尿病和囊性纤维化，是由于蛋白质错误折叠导致其3D构象从天然（可溶）改变为非天然（不溶）折叠结构，称为淀粉样蛋白。了解这种错误折叠和由此产生的三维构象，诱导病理生理细胞活动和变性，一直是最重要的研究领域之一，但也具有挑战性。最初的想法认为，错误折叠诱导的纤维结构导致功能获得，并通过自由基氧化应激和/或非特异性膜渗漏改变细胞膜组成，从而破坏离子稳态，从而诱导病理生理。然而，最近的研究表明，球状的、非纤维状的大分子复合物足以诱导细胞病理，可能是直接通过它们的膜穿孔。事实上，据报道，小单体和寡聚肽在人工和天然细胞膜中诱导离子电导。这些假设离子通道的三维结构和配体诱导的构象变化尚不清楚。了解淀粉样蛋白肽通道的三维结构及其在细胞毒性中的作用，对于设计对抗药物和合理治疗构象疾病的策略至关重要。本提案旨在研究关于蛋白质构象疾病的假设驱动问题，并设计技术来实现目标。我们的总体假设是，蛋白质错误折叠疾病是由于它们的球状（不是纤维状）构象形成离子通道和分子造成的，其他干预措施，调节它们的结构和活动，可以用于有效的治疗。我们提出以下具体目的：1 .研究脂质膜中重组的球状淀粉样蛋白肽的三维离子通道结构；2：检查对各种药物和多肽的反应的开闭通道构象；3：使用afm -离子电导测量系统和药物将通道的开合构象与通道电导相关联。因此，我们的目标是提供一个独特而可行的模型系统，用于筛选假定的药物分子和设计治疗方法，用于广泛的由离子通道结构和活性缺陷引起的退行性疾病，即“通道病变”。

DESCRIPTION (provided by applicant): Protein conformational diseases, including neurodegenerative (Alzheimer's and Parkinson's diseases), type II diabetes and cystic fibrosis result from protein misfolding that alters their 3D conformations from native (soluble) to non-native (insoluble) folded structures, called amyloids. Understanding such misfolding and the resulting 3D conformations that induce pathophysiological cellular activity and degeneration have been one of the most important and yet challenging areas of research. The original idea suggests that misfolding-induced fibrillar structure results into a gain-of-function and induce pathophysiology by altering cell membrane composition via free radical oxidative stress and/or non-specific membrane leakage and thence destabilizing ionic homeostasis. However, recent studies show that globular, non-fibrillar macromolecular complexes are sufficient to induce cell pathology, presumably directly by their membrane poration. Indeed, small monomeric and oligomeric peptides are reported to induce ionic conductances in artificial as well as native cell membranes. 3D structure and ligand-induced conformational changes of these putative ion channels are poorly understood. An understanding of the 3-D structure of amyloidogenic peptide-channel and its role in cell toxicity is essential for designing counteracting drugs and rational strategies for treatment of conformational diseases. This proposal aims to examine hypothesis-driven questions about protein conformational diseases and also design techniques to accomplish the goals. Our overall hypothesis is that protein misfolding diseases result from their globular (not fibrillar) conformation that forms ion channels and molecules and that other interventions, to modulate their structure and activity, could be used for effective therapy. We propose the following Specific Aims: 1: examine 3D ion-channel structure of globular amyloidogenic peptides reconstituted in lipid membrane; 2: Examine open-closed channel conformations in response to various pharmacological agents and peptides; 3: correlate channel open-close conformations with channel conductance using a combined AFM-ion conductance measurement system and pharmacological agents. Thus we aim to provide a unique and feasible model system for screening putative drug molecules and designing therapeutics for a wide range of degenerative diseases that result from defects in ion channel structure and activity, the "channelopathies".