Zhu Haitao, Luo Liqun
Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA.
Neuron. 2004 Apr 8;42(1):63-75. doi: 10.1016/s0896-6273(04)00142-4.
The cadherin superfamily of cell adhesion molecules have been proposed to play important roles in determining synaptic specificity in developing nervous systems. We examine the function of N-cadherin in Drosophila second order olfactory projection neurons (PNs), each of which must selectively target their dendrites to one of approximately 50 glomeruli. Our results do not support an instructive role for N-cadherin in selecting dendritic targets; rather, N-cadherin is essential for PNs to restrict their dendrites to single glomeruli. Mosaic analyses suggest that N-cadherin mediates dendro-dendritic interactions between PNs and thus contributes to refinement of PN dendrites to single glomeruli. N-cadherin is also essential for the development of PN axon terminal arbors in two distinct central targets: regulating branch stability in the lateral horn and restricting high-order branching in the mushroom body. Although the N-cadherin locus potentially encodes eight alternatively spliced isoforms, transgenic expression of one isoform is sufficient to rescue all phenotypes.
细胞粘附分子的钙粘蛋白超家族被认为在发育中的神经系统中确定突触特异性方面发挥重要作用。我们研究了果蝇二阶嗅觉投射神经元（PNs）中N-钙粘蛋白的功能，每个投射神经元必须将其树突选择性地靶向大约50个小球体中的一个。我们的结果不支持N-钙粘蛋白在选择树突靶点方面具有指导作用；相反，N-钙粘蛋白对于投射神经元将其树突限制在单个小球体中至关重要。镶嵌分析表明，N-钙粘蛋白介导投射神经元之间的树突-树突相互作用，从而有助于将投射神经元的树突细化为单个小球体。N-钙粘蛋白对于投射神经元轴突终末分支在两个不同的中枢靶点的发育也至关重要：调节侧角的分支稳定性并限制蘑菇体中的高阶分支。尽管N-钙粘蛋白基因座可能编码八种可变剪接异构体，但一种异构体的转基因表达足以挽救所有表型。
