Fibronectin intrabodies generated with mRNA display (FingRs) are a recently developed tool for labeling excitatory or inhibitory synapses, with the benefit of not altering endogenous synaptic protein expression levels or synaptic transmission. Here, we generated a viral vector FingR toolbox that allows for multi-color, neuron-type-specific labeling of excitatory or inhibitory synapses in multiple brain regions. We screened various fluorophores, FingR fusion configurations, and transcriptional control regulations in adeno-associated virus (AAV) and retrovirus vector designs. We report the development of a red FingR variant and demonstrated dual labeling of excitatory and inhibitory synapses in the same cells. Furthermore, we developed cre-inducible FingR AAV variants and demonstrated their utility, finding that the density of inhibitory synapses in aspiny striatal cholinergic interneurons remained unchanged in response to dopamine depletion. Finally, we generated FingR retroviral vectors, which enabled us to track the development of excitatory and inhibitory synapses in hippocampal adult-born granule cells.

通过 mRNA 展示 (FingR) 生成的纤连蛋白胞内抗体是最近开发的一种用于标记兴奋性或抑制性突触的工具，其优点是不改变内源性突触蛋白表达水平或突触传递。在这里，我们生成了一个病毒载体 FingR 工具箱，可以对多个大脑区域的兴奋性或抑制性突触进行多色、神经元类型特异性标记。我们筛选了腺相关病毒 (AAV) 和逆转录病毒载体设计中的各种荧光团、FingR 融合构型和转录控制调控。我们报告了红色 FingR 变体的开发，并证明了同一细胞中兴奋性和抑制性突触的双重标记。此外，我们开发了 cre 诱导型 FingR AAV 变体并证明了其实用性，发现无刺纹状体胆碱能中间神经元中的抑制性突触密度在响应多巴胺耗竭时保持不变。最后，我们生成了 FingR 逆转录病毒载体，这使我们能够追踪海马成年颗粒细胞中兴奋性和抑制性突触的发育。