Prakash Saurabh, Caldwell Jason C, Eberl Daniel F, Clandinin Thomas R
Department of Neurobiology, 299 W. Campus Drive, Stanford University, Stanford, California 94305, USA.
Nat Neurosci. 2005 Apr;8(4):443-50. doi: 10.1038/nn1415. Epub 2005 Feb 27.
Classical cadherins have been proposed to mediate interactions between pre- and postsynaptic cells that are necessary for synapse formation. We provide the first direct, genetic evidence in favor of this model by examining the role of N-cadherin in controlling the pattern of synaptic connections made by photoreceptor axons in Drosophila. N-cadherin is required in both individual photoreceptors and their target neurons for photoreceptor axon extension. Cell-by-cell reconstruction of wild-type photoreceptor axons extending within mosaic patches of mutant target cells shows that N-cadherin mediates attractive interactions between photoreceptors and their targets. This interaction is not limited to those cells that will become the synaptic partners of photoreceptors. Multiple N-cadherin isoforms are produced, but single isoforms can substitute for endogenous N-cadherin activity. We propose that N-cadherin mediates a homophilic, attractive interaction between photoreceptor growth cones and their targets that precedes synaptic partner choice.
经典钙黏蛋白被认为可介导突触前和突触后细胞之间的相互作用，而这种相互作用对于突触形成是必需的。我们通过研究N-钙黏蛋白在控制果蝇光感受器轴突形成突触连接模式中的作用，首次提供了支持该模型的直接遗传学证据。在单个光感受器及其靶神经元中，N-钙黏蛋白对于光感受器轴突的延伸都是必需的。对在突变靶细胞镶嵌斑块内延伸的野生型光感受器轴突进行逐个细胞重建显示，N-钙黏蛋白介导了光感受器与其靶标之间的吸引性相互作用。这种相互作用并不局限于那些将成为光感受器突触伙伴的细胞。虽然会产生多种N-钙黏蛋白异构体，但单一异构体可替代内源性N-钙黏蛋白的活性。我们提出，N-钙黏蛋白介导了光感受器生长锥与其靶标之间在突触伙伴选择之前的一种嗜同性、吸引性相互作用。
