The Dscam family of immunoglobulin cell surface proteins mediates recognition events between neurons that play an essential role in the establishment of neural circuits. The Drosophila Dscam1 locus encodes tens of thousands of cell surface proteins via alternative splicing. These isoforms exhibit exquisite isoform-specific binding in vitro that mediates homophilic repulsion in vivo. These properties provide the molecular basis for self-avoidance, an essential developmental mechanism that allows axonal and dendritic processes to uniformly cover their synaptic fields. In a mechanistically similar fashion, homophilic repulsion mediated by Drosophila Dscam2 prevents processes from the same class of cells from occupying overlapping synaptic fields through a process called tiling. Genetic studies in the mouse visual system support the view that vertebrate DSCAM also promotes both self-avoidance and tiling. By contrast, DSCAM and DSCAM-L promote layer-specific targeting in the chick visual system, presumably through promoting homophilic adhesion. The fly and mouse studies underscore the importance of homophilic repulsion in regulating neural circuit assembly, whereas the chick studies suggest that DSCAM proteins may mediate a variety of different recognition events during wiring in a context-dependent fashion.

中文翻译：

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Dscam 介导的细胞识别调节神经回路形成。

免疫球蛋白细胞表面蛋白的 Dscam 家族介导神经元之间的识别事件，这些神经元在神经回路的建立中起着至关重要的作用。果蝇 Dscam1 基因座通过选择性剪接编码数以万计的细胞表面蛋白。这些同种型在体外表现出精致的同种型特异性结合，可介导体内嗜同性排斥。这些特性为自我回避提供了分子基础，自我回避是一种基本的发育机制，允许轴突和树突过程均匀地覆盖它们的突触区域。以机械相似的方式，由果蝇 Dscam2 介导的嗜同性排斥可防止来自同一类细胞的过程通过称为平铺的过程占据重叠的突触场。小鼠视觉系统的遗传研究支持脊椎动物 DSCAM 也促进自我回避和平铺的观点。相比之下，DSCAM 和 DSCAM-L 促进小鸡视觉系统中的层特异性靶向，大概是通过促进嗜同性粘附。果蝇和小鼠研究强调了嗜同性排斥在调节神经回路组装中的重要性，而小鸡研究表明 DSCAM 蛋白可能在布线过程中以上下文相关的方式介导各种不同的识别事件。