The mouse visual system serves as an accessible model to understand mammalian circuit wiring. Despite rich knowledge in retinal circuits, the long-range connectivity map from distinct retinal ganglion cell (RGC) types to diverse brain neuron types remains unknown. In this study, we developed an integrated approach, called Trans-Seq, to map RGCs to superior collicular (SC) circuits. Trans-Seq combines a fluorescent anterograde trans-synaptic tracer, consisting of codon-optimized wheat germ agglutinin fused to mCherry, with single-cell RNA sequencing. We used Trans-Seq to classify SC neuron types innervated by genetically defined RGC types and predicted a neuronal pair from αRGCs to Nephronectin-positive wide-field neurons (NPWFs). We validated this connection using genetic labeling, electrophysiology and retrograde tracing. We then used transcriptomic data from Trans-Seq to identify Nephronectin as a determinant for selective synaptic choice from αRGC to NPWFs via binding to Integrin α8β1. The Trans-Seq approach can be broadly applied for post-synaptic circuit discovery from genetically defined pre-synaptic neurons.

小鼠视觉系统是了解哺乳动物电路布线的可访问模型。尽管我们对视网膜回路有丰富的了解，但从不同的视网膜神经节细胞（RGC）类型到不同的脑神经元类型的远程连接图仍然未知。在这项研究中，我们开发了一种称为 Trans-Seq 的集成方法，将 RGC 映射到上丘 (SC) 回路。 Trans-Seq 将荧光顺行突触示踪剂（由与 mCherry 融合的密码子优化的小麦胚芽凝集素组成）与单细胞 RNA 测序相结合。我们使用 Trans-Seq 对由遗传定义的 RGC 类型支配的 SC 神经元类型进行分类，并预测从 αRGC 到肾连蛋白阳性广域神经元 (NPWF) 的神经元对。我们使用基因标记、电生理学和逆行追踪验证了这种联系。然后，我们使用 Trans-Seq 的转录组数据来鉴定肾连蛋白通过与整合素 α8β1 结合，作为从 αRGC 到 NPWF 的选择性突触选择的决定因素。 Trans-Seq 方法可广泛应用于从基因定义的突触前神经元发现突触后回路。