Nature：几种Dscams分子在脊椎动物神经联结中起作用

Dscams是免疫球蛋白超级家族的黏附分子。果蝇Dscams已被发现与神经联结的组织相关，但人们对脊椎动物中密切相关的分子的功能却知之甚少。现在，Masahito Yamagata和Joshua Sanes发现，Dscams-1和Dscams-2在鸡视网膜特定层联结的成形中能发挥一定作用。另外两种黏附分子，即Sidekick-1和Sidekick-2，以一种类似的方式发挥作用。这些分子广泛分布在神经系统中，可能是使大脑中神经联结成形的一个“黏附代码”的构成部分。关于Dscams在脊椎动物神经成形中重要性的进一步证据来自Fuerst等人，他们发现DSCAM（即“唐氏综合征细胞黏附分子”的英文首字母缩写）在小鼠视网膜神经回路的形成中发挥一定作用。

生物谷推荐英文原文：

Nature 451, 465-469 (24 January 2008) | doi:10.1038/nature06469; Received 31 August 2007; Accepted 12 November 2007

Dscam and Sidekick proteins direct lamina-specific synaptic connections in vertebrate retina

Masahito Yamagata1 & Joshua R. Sanes1

Department of Molecular and Cellular Biology and Center for Brain Science, Harvard University, Cambridge, Massachusetts 02138, USA

Correspondence to: Joshua R. Sanes1 Correspondence and requests for materials should be addressed to J.R.S. (Email: sanesj@mcb.harvard.edu).

Synaptic circuits in the retina transform visual input gathered by photoreceptors into messages that retinal ganglion cells (RGCs) send to the brain. Processes of retinal interneurons (amacrine and bipolar cells) form synapses on dendrites of RGCs in the inner plexiform layer (IPL). The IPL is divided into at least 10 parallel sublaminae; subsets of interneurons and RGCs arborize and form synapses in just one or a few of them1, 2, 3. These lamina-specific circuits determine the visual features to which RGC subtypes respond3, 4, 5. Here we show that four closely related immunoglobulin superfamily (IgSF) adhesion molecules—Dscam (Down's syndrome cell adhesion molecule), DscamL (refs 6–9), Sidekick-1 and Sidekick-2 (ref. 10)—are expressed in chick by non-overlapping subsets of interneurons and RGCs that form synapses in distinct IPL sublaminae. Moreover, each protein is concentrated within the appropriate sublaminae and each mediates homophilic adhesion. Loss- and gain-of-function studies in vivo indicate that these IgSF members participate in determining the IPL sublaminae in which synaptic partners arborize and connect. Thus, vertebrate Dscams, like Drosophila Dscams11, 12, 13, 14, 15, 16, 17, 18, 19, play roles in neural connectivity. Together, our results on Dscams and Sidekicks suggest the existence of an IgSF code for laminar specificity in retina and, by implication, in other parts of the central nervous system.