In the Drosophila brain, neurons form genetically specified synaptic connections with defined neuronal targets. It is proposed that each central nervous system neuron expresses specific cell surface proteins, which act as identification tags. Through an RNAi screen of cell surface molecules in the Drosophila visual system, we found that the cell adhesion molecule Klingon (Klg) plays an important role in repressing the ectopic formation of extended axons, preventing the formation of excessive synapses. Cell-specific manipulation of klg showed that Klg is required in both photoreceptors and the glia, suggesting that the balanced homophilic interaction between photoreceptor axons and the glia is required for normal synapse formation. Previous studies suggested that Klg binds to cDIP and our genetic analyses indicate that cDIP is required in glia for ectopic synaptic repression. These data suggest that Klg play a critical role together with cDIP in refining synaptic specificity and preventing unnecessary connections in the brain.

中文翻译：

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细胞表面分子Klingon介导果蝇视觉系统中突触特异性的细化。

在果蝇的大脑中，神经元与指定的神经元靶标形成遗传指定的突触连接。提出每个中枢神经系统神经元表达特定的细胞表面蛋白，其充当识别标签。通过果蝇视觉系统中细胞表面分子的RNAi筛选，我们发现细胞粘附分子Klingon（Klg）在抑制延长轴突的异位形成，防止过度突触形成中起重要作用。Klg的细胞特异性操作表明，感光细胞和神经胶质细胞都需要Klg，这表明正常突触形成需要感光细胞轴突和神经胶质之间的平衡同质相互作用。先前的研究表明，Klg与cDIP结合，而我们的遗传分析表明，神经胶质中cDIP是异位突触抑制所必需的。这些数据表明，Klg与cDIP一起在完善突触特异性和预防大脑中不必要的连接中起着至关重要的作用。