Nervous system function relies on precise synaptic connections. A number of widely-conserved cell adhesion proteins are implicated in cell recognition between synaptic partners, but how these proteins act as a group to specify a complex neural network is poorly understood. Taking advantage of known connectivity in C. elegans, we identified and studied cell adhesion genes expressed in three interacting neurons in the mating circuits of the adult male. Two interacting pairs of cell surface proteins independently promote fasciculation between sensory neuron HOA and its postsynaptic target interneuron AVG: BAM-2/neurexin-related in HOA binds to CASY-1/calsyntenin in AVG; SAX-7/L1CAM in sensory neuron PHC binds to RIG-6/contactin in AVG. A third, basal pathway results in considerable HOA-AVG fasciculation and synapse formation in the absence of the other two. The features of this multiplexed mechanism help to explain how complex connectivity is encoded and robustly established during nervous system development.

中文翻译：

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多种保守的细胞粘附蛋白相互作用介导了秀丽隐杆线虫感觉回路的神经布线

神经系统功能依赖于精确的突触连接。许多广泛保守的细胞粘附蛋白与突触伙伴之间的细胞识别有关，但这些蛋白质如何作为一个群体来指定复杂的神经网络却知之甚少。利用线虫中已知的连接性，我们鉴定并研究了在成年雄性交配回路中三个相互作用的神经元中表达的细胞粘附基因。两对相互作用的细胞表面蛋白独立促进感觉神经元 HOA 与其突触后靶中间神经元 AVG 之间的成束：HOA 中 BAM-2/neurexin 相关与 AVG 中的 CASY-1/calsyntenin 结合；感觉神经元 PHC 中的 SAX-7/L1CAM 与 AVG 中的 RIG-6/contactin 结合。三分之一，基础通路导致相当大的 HOA-AVG 肌束颤动和突触形成，而其他两个通路不存在。这种多路复用机制的特征有助于解释在神经系统发育过程中复杂的连接是如何编码和稳健建立的。