Dissection of synapse induction by neuroligins -: Effect of a neuroligin mutation associated with autism
Dissection of synapse induction by neuroligins -: Effect of a neuroligin mutation associated with autism
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DOI：
10.1074/jbc.m410723200
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发表时间：
2005-06-10
影响因子：
4.8
通讯作者：
Südhof, TC
中科院分区：
文献类型：
--
作者：
Chubykin, AA;Liu, XR;Südhof, TC
为了研究神经胶质素对突触形成的影响，我们将海马神经元与表达野生型和突变型神经胶质素的COS细胞共培养。COS细胞的大尺寸使得测试神经脂素在扩大表面积上的作用成为可能。我们发现，在细胞表面显示的野生型神经素的均匀草坪触发了数百个均匀大小的单个突触接触的形成，这些突触接触被标记为神经素抗体。电子显微镜显示，这些人工突触包含一个突触前活跃区，其中有停靠的囊泡，并且通常具有突触后密度。神经素1、2和3在该实验中有活性。神经胶质素1的两个表面环的突变破坏了神经胶质素与神经素1 β的结合，神经素1 β是突触后神经胶质素的突触前结合伙伴，并阻断了突触的形成。一项对突变的神经脂素的分析表明，氨基酸替代与自闭症患者中描述的突变相对应，证实了先前的报道，即这些突变的神经脂素转运到细胞表面的能力受到损害。然而，到达细胞表面的一小部分突变的神经脂素仍然诱导了突触的形成。综上所述，我们的数据表明，神经胶质素通常以一种与β -神经素结合相关的方式促进人工突触的形成，并导致形态学上分化良好的突触，并且在自闭症谱系障碍中发现的神经胶质素突变会损害细胞表面运输，但不会完全消除突触形成活性。
To study synapse formation by neuroligins, we cocultured hippocampal neurons with COS cells expressing wild type and mutant neuroligins. The large size of COS cells makes it possible to test the effect of neuroligins presented over an extended surface area. We found that a uniform lawn of wild type neuroligins displayed on the cell surface triggers the formation of hundreds of uniformly sized, individual synaptic contacts that are labeled with neurexin antibodies. Electron microscopy revealed that these artificial synapses contain a presynaptic active zone with docked vesicles and often feature a postsynaptic density. Neuroligins 1, 2, and 3 were active in this assay. Mutations in two surface loops of neuroligin 1 abolished neuroligin binding to neurexin 1 beta, a presumptive presynaptic binding partner for postsynaptic neuroligins, and blocked synapse formation. An analysis of mutant neuroligins with an amino acid substitution that corresponds to a mutation described in patients with an autistic syndrome confirmed previous reports that these mutant neuroligins have a compromised capacity to be transported to the cell surface. Nevertheless, the small percentage of mutant neuroligins that reached the cell surface still induced synapse formation. Viewed together, our data suggest that neuroligins generally promote artificial synapse formation in a manner that is associated with beta-neurexin binding and results in morphologically well differentiated synapses and that a neuroligin mutation found in autism spectrum disorders impairs cell-surface transport but does not completely abolish synapse formation activity.