高含量的成像检测方法的肉毒毒素抑制剂的鉴定
Summary
Botulinum neurotoxin is one of the most potent toxins among Category-A biothreat agents, yet a post-exposure therapeutic is not available. The high content imaging approach is a powerful methodology for identifying novel inhibitors as it enables multiparameter screening using biologically relevant motor neurons, the primary target of this toxin.
Abstract
Synaptosomal-associated protein-25 (SNAP-25) is a component of the soluble NSF attachment protein receptor (SNARE) complex that is essential for synaptic neurotransmitter release. Botulinum neurotoxin serotype A (BoNT/A) is a zinc metalloprotease that blocks exocytosis of neurotransmitter by cleaving the SNAP-25 component of the SNARE complex. Currently there are no licensed medicines to treat BoNT/A poisoning after internalization of the toxin by motor neurons. The development of effective therapeutic measures to counter BoNT/A intoxication has been limited, due in part to the lack of robust high-throughput assays for screening small molecule libraries. Here we describe a high content imaging (HCI) assay with utility for identification of BoNT/A inhibitors. Initial optimization efforts focused on improving the reproducibility of inter-plate results across multiple, independent experiments. Automation of immunostaining, image acquisition, and image analysis were found to increase assay consistency and minimize variability while enabling the multiparameter evaluation of experimental compounds in a murine motor neuron system.
Introduction
细菌肉毒梭菌产生的肉毒杆菌神经毒素，对人类已知1是最有效的生物毒素之一。有7个不同的血清型肉毒毒素（肉毒毒素/ AG）。肉毒毒素/ A-胆引起麻痹的神经肌肉接头处由于SNARE复合体蛋白水解2,3。 SNARE蛋白水解阻止神经递质囊泡膜融合，从而阻止神经递质胞吐4。具体的SNARE目标取决于所涉及的中毒过程中的特殊肉毒毒素血清型。肉毒毒素/ A和肉毒毒素/ E切割SNAP-25，而肉毒毒素/ C切割两种SNAP-25和突触5。剩下的血清型切割突触（也称为囊泡相关膜蛋白（VAMP）。肉毒毒素/ A被选为试验发展，因为它是负责自然发生的肉毒杆菌中毒的比例很高，并具有行动6。发展小分子的最长期限治疗对肉毒毒素/ A是主要目标我们的药物研发项目，并利用传统的基于目标的方法来确定活性位点的蛋白水解酶抑制剂7，8-10。然而，创建活性位点抑制剂具有抗多种血清型和后曝光功效广谱活性的将可能是具有挑战性的。
因此，我们已经实现了一个创新的，表型的药物发现，使用肉毒毒素SNAP-25的切割作为一个功能的端点，以确定小分子，可以阻止肉毒毒素介导的运动神经中毒的方法。 SNAP-25所需的神经递质的释放，如SNAP-25的降解是预测性麻痹和致死的体内 。例如，基于细胞的筛选可能导致发现的负责毒素失活或抑制毒素途径的靶细胞内的细胞因子的新调节剂。在表型检测发展的一个重要因素是生理上相关的生物模型的选择。 W¯¯e和其他人描述了小鼠胚胎干（ES）细胞衍生的运动神经元概括初级运动神经元的免疫学性质，包括SNAP-25 -11- 13的表达。重要的是，这些蜂窝系统到的BoNT / A中毒高度敏感和演示的SNAP-25的剂量依赖性裂解响应于增加毒素11,12的浓度。在分化的运动神经元也产生在量，足以适用于高通量板为基础的分析，并允许细胞试验的阵列的设计。
表型分析是利用两种不同的抗体，肉毒毒素/鼠标运动神经元文化的陶醉在量化内源性表达的全长SNAP-25的裂解免疫荧光法。羧基末端肉毒毒素/ A裂解敏感（BACS）抗体只识别全长SNAP-25允许SNAP-25的肉毒毒素/ A介导的蛋白水解的评价在小鼠运动神经元表达10。的盐酸法的示意图示于图1。
Protocol
Representative Results
Discussion
肉毒杆菌神经毒素，相对缓解他们的武器化的高效力，导致其分类为A类（最高优先级）生物威胁剂由美国疾病控制和预防。不幸的是，没有FDA批准的治疗剂来对抗的BoNT中毒后的毒素已被内化的运动神经元。促进从肉毒毒素中毒的神经元恢复任何成药机制可能会导致对潜在疗法的发展对这种生物的威胁，以保护双方的军种和公众。在这篇文章中，我们提出了一个详细的分析HCI协议进行筛选的致命?…
Declarações
The authors have nothing to disclose.
Acknowledgements
Funding was provided by the Joint Science and Technology Office – Chemical Biological Defense (JSTO-CBD) Defense Threat Reduction Agency (DTRA) under sponsor project number CCAR# CB3675 and National Institutes of Health (1 R21 AI101387-01 and 5 U01AI082051-05).
Materials
| Name of Reagent/ Equipment | Company | Catalog Number | Comments/Description |
| Botulinum neurotoxin A | Metabiologics | NA | No catalog number |
| Microtitre plates | Greiner | 655946 | Poly-D-Lysine 96-well plates |
| BACs antibody | Lampire Biological | NA | |
| Microchem | National | 0255 | |
| Methanol | Thermo Scientific | A412-20 | |
| Formaldehyde | Thermo Scientific | 28908 | |
| Horse serum | Invitrogen | 16050 | |
| PE JANUS MDT Mini Automated Workstation | Perkin Elmer | AJMDT01 | |
| Opera | Perkin Elmer | OP-QEHS-01 | |
| Triton X 100 | Sigma-Aldrich | 9002-93-1 | |
| BIII tubulin antibody | R&D Systems | BAM1195 | |
| Tween 20 | Sigma | P1379-1L | |
| Hoechst 33342dye | Invitrogen | 3570 | |
| Antimouse IgG | Invitrogen | A21236 | |
| Anti rabbit IgG | Invitrogen | A10042 | |
| Columbus Image analysis software | Perkin Elmer | Ver 2.4 | |
| Spotfire | Perkin Elmer | Ver 5.5 | |
| Clorox bleach | Fisher Scientific | 18-861-284 | |
| PlateStack |
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