Chemical Probes for Amyloid Oligomers

有了这个奖项，化学部的生命过程化学项目资助了加州大学欧文分校的James Nowick博士，研究一类染料分子和与淀粉样蛋白疾病（如阿尔茨海默病）相关的肽分子小聚集体之间的相互作用。这些聚集体被称为“低聚物”，被认为是造成与该疾病相关的神经变性的破坏性物质。染料长期以来被用作化学探针来观察和监测淀粉样蛋白纤维的形成，最近被证明在成像中以非侵入方式监测大脑中的淀粉样蛋白纤维是有价值的。淀粉样蛋白低聚物的可比小分子探针是缺乏的。淀粉样蛋白低聚物的化学探针提供了在体外、生物组织和活细胞中监测和可视化淀粉样蛋白低聚物的希望。目前的项目将导致更好地理解染料分子和低聚物之间的相互作用，并将开发染料作为研究淀粉样蛋白低聚物的有用工具。这种追求将允许研究生获得博士学位，并以熟练的科学家的身份进入美国劳动力市场，本科生接受研究培训，进入研究生院或以学士学位化学家的身份进入劳动力市场。通过对高中学生的培训和K-12的推广，将产生额外的影响。目前的项目依赖于首席研究员实验室的两项发现。第一个发现是源自β -淀粉样肽的大环β -发夹肽组装形成具有明确定义的三重对称的三聚体。第二个发现是，三苯基甲烷染料，如结晶紫，以低微摩尔亲和力与三聚体结合。染料对低聚物有明显的反应，从紫色变成蓝色，变成荧光。淀粉样蛋白低聚物反应的这些光谱变化也可以用分光光度法或荧光显微镜观察到。由于这些原因，三苯基甲烷染料作为淀粉样蛋白低聚物的化学探针提供了希望。将实现两个目标。第一个目的是更好地了解三苯基甲烷染料与大环-发夹肽三聚体的结合。这一目标将通过对三聚体和染料的结构进行修饰的结构-活性-关系研究来实现。第二个目标是开发三苯基甲烷染料作为全长β -淀粉样肽的合成和生物低聚物的化学探针。一组研究将集中于开发具有光反应官能团的三苯甲烷染料，作为β -淀粉样肽低聚物的光亲和标记。第二组实验将集中于开发固定化三苯甲烷染料，以允许基于亲和的纯化组织中的β -淀粉样蛋白低聚物。其他的实验将集中在使用三苯基甲烷染料来发现淀粉样蛋白低聚物的新配体。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With this award, the Chemistry of Life Processes program in the Chemistry Division is funding Dr. James Nowick from the University of California Irvine to investigate interactions between a class of dye molecules and small aggregates of peptide molecules that are associated with amyloid diseases, such as Alzheimer's disease. These aggregates, termed "oligomers," are thought to be the damaging species responsible for neurodegeneration associated with the disease. Dyes have long been used as chemical probes to visualize and monitor amyloid fibril formation and recently have proven valuable in imaging to monitor amyloid fibrils in the brain in a non-invasive fashion. Comparable small molecule probes for amyloid oligomers are lacking. Chemical probes for amyloid oligomers offer the promise of monitoring and visualizing amyloid oligomers in vitro, in biological tissues, and in living cells. The current project will lead to a better understanding of the interactions between the dye molecules and the oligomers and will develop the dyes as useful tools with which to study amyloid oligomers. This pursuit will allow graduate students to earn Ph.D. degrees and enter the US work force as skilled scientists and undergraduate students to receive training in research and go to graduate school or enter the work force as a B.S. Chemists. Additional impact will be achieved through the training of high school students and through K-12 outreach.The current project relies on two discoveries in the laboratory of the Principal Investigator. The first discovery is that macrocyclic beta-hairpin peptides derived from the beta-amyloid peptide assemble to form trimers with well-defined three-fold symmetry. The second discovery is that triphenylmethane dyes such as crystal violet bind to the trimers with low-micromolar affinities. The dyes provide a visible response to the oligomers, changing color from violet to blue and becoming fluorescent. These spectral changes in response to amyloid oligomers can also be measured spectrophotometrically or observed in fluorescence microscopy. For these reasons, triphenylmethane dyes offer promise as chemical probes for amyloid oligomers. Two aims will be achieved. The first aim is to better understand the binding of triphenylmethane dyes to trimers of macrocyclic beta-hairpin peptides. This goal will be achieved through structure-activity-relationship studies in which the structures of the trimers and the dyes are modified. The second aim is to develop triphenylmethane dyes as chemical probes for synthetic and biogenic oligomers of the full-length beta-amyloid peptide. One set of studies will focus on developing triphenylmethane dyes bearing photo-reactive functional groups as photoaffinity labels for oligomers of the beta-amyloid peptide. A second set of experiments will focus on developing immobilized triphenylmethane dyes to allow affinity-based purification of beta-amyloid oligomers from tissue. Additional experiments will focus on using triphenylmethane dyes to discover novel ligands for amyloid oligomers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.