Chemical Targeting of Sensors and Pharmacological Probes in the Brain

总结 大脑中传感器和药理学探针的化学靶向 不存在能够监测和/或调节哺乳动物中的特定回路和细胞的通用工具。 大脑通过纯化学手段。我们最近公开了一种聚合物平台，用于电压的化学传递， 敏感染料（VSD）对脑中特定细胞类型（单胺能神经元及其延伸）的作用，作为第一个 非遗传系统的一个例子，能够在脑组织中靶向递送高度亲脂性分子。我们有 表明葡聚糖，一种细菌多糖，可以作为一种极性聚合物载体， 包封亲脂性VSD，使其通过脑组织，并将其部署在特定的感兴趣的细胞类型， 归巢配体的方式。拟议的研究旨在建立在这个概念验证的例子，并开发 一种用于将亲脂性传感器和致动器/药物递送到大脑中特定细胞类型的通用平台。在Aim中 1A我们将开发基于配体导向的酰基咪唑化学的无痕共价标记技术，以a） 能够实现细胞类型特异性靶向，而不会因药物的药理学作用而长期干扰系统。 配体，和B）在离子转运蛋白（AMPA受体）附近共价结合的电压传感器 和多巴胺转运蛋白）来测量膜电位的局部变化。在目标1B中，我们将利用 通过将平台扩展到双药物靶向， 多巴胺受体D2激动剂特异性地作用于表达D2的中型棘神经元（D2-MSNs），但不 纹状体中的多巴胺能轴突，通过腺苷受体A2 A拮抗剂（D2-MSN标记物）。 这将为细胞选择性药理学提供一个平台，具有治疗神经退行性疾病（例如， 帕金森氏病）和精神疾病。在目标2中，我们专注于a）优化荧光VSD，用于高 使用葡聚糖平台的灵敏度和可靶向性;和B）将靶向平台扩展到电压传感器 能够实现包括短波红外荧光显微镜和光声 显像在目标3中，我们将通过调整聚合物分子， 权重和替代模式。我们还将探索其他糖基聚合物作为递送系统， 脑中的亲脂性货物，包括环糊精和聚（苯乙烯-醚-海藻糖）。这五年的成果 该计划承诺提供一个通用和优化的平台，用于提供亲脂性传感器和致动器， 大脑中的特定细胞类型。化学靶向方法消除了对基因操作的需要， 因此，从长远来看，它将适用于人类和其他生物体， 适应基因操作。

SUMMARY Chemical Targeting of Sensors and Pharmacological Probes in the Brain There are no general tools that enable monitoring and/or modulation of specific circuits and cells in the mammalian brain by purely chemical means. We have recently disclosed a polymer platform for chemical delivery of voltage sensitive dyes (VSDs) to specific cell types in the brain (monoaminergic neurons and their extensions), as a first example of a non-genetic system enabling targeted delivery of highly lipophilic molecules in brain tissue. We have shown that dextran, a bacterial polysaccharide, can function as a polar polymer carrier which dynamically encapsulates the lipophilic VSD to carry it through brain tissue and deploy it at a specific cell type of interest by the means of a homing ligand. The proposed research aims to build on this proof-of-concept example and develop a general platform for delivery of lipophilic sensors and actuators/drugs to specific cell types in the brain. In Aim 1A we will develop traceless covalent labeling techniques based on ligand-directed acyl imidazole chemistry to a) enable cell-type specific targeting without long-term perturbation of the system by pharmacological effects of the ligand, and b) covalently immobilize voltage sensors in the vicinity of ion transporting proteins (AMPA receptor and dopamine transporter) to measure local changes of membrane potential. In Aim 1B, we will leverage the pharmacological effects of the ligands by extending the platform to dual-drug targeting which will enable delivery of dopamine receptor D2 agonists specifically to D2-expressing medium spiny neurons (D2-MSNs), but not dopaminergic axons in the striatum, by the means of an adenosine receptor A2A antagonist (a D2-MSN marker). This will provide a platform for cell selective pharmacology with therapeutic potential for neurodegenerative (e.g. Parkinson’s disease) and psychiatric disorders. In Aim 2 we focus on a) optimization of fluorescent VSDs for high sensitivity and targetability using the dextran platform; and b) extension of the targeting platform to voltage sensors enabling novel imaging modalities including short wave infrared fluorescence microscopy and photoacoustic imaging. In Aim 3 we will systematically optimize the dextran delivery platform by tuning the polymer molecular weight and substitution pattern. We will also explore other saccharide-based polymers as delivery systems for lipophilic cargo in the brain, including cyclodextrins and poly(styrene-ether-trehalose). The outcome of this 5-year program promises to provide a general and optimized platform for delivery of lipophilic sensor and actuators to specific cell types in the brain. The chemical targeting approach eliminates the need for genetic manipulation of the brain and thus will be, in a long-term perspective, applicable to humans and other organisms not readily adaptable for genetic manipulations.