NGL-3-induced presynaptic differentiation of hippocampal neurons in an afadin-dependent, nectin-1-independent manner
NGL-3-induced presynaptic differentiation of hippocampal neurons in an afadin-dependent, nectin-1-independent manner
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DOI：
10.1111/gtc.12510
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发表时间：
2017-08-01
期刊：
影响因子：
2.1
通讯作者：
Takai, Yoshimi
中科院分区：
文献类型：
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作者：
Maruo, Tomohiko;Mandai, Kenji;Takai, Yoshimi
海马苔藓纤维突触与学习和记忆有关，具有复杂的结构。我们之前已经使用 afadin 缺陷小鼠证明，afadin 在该突触的结构和功能分化中发挥着多种作用。我们在这里使用培养的海马神经元和表达突触细胞粘附分子（CAM）的非神经元 COS-7 细胞的共培养系统研究了 afadin 是否参与海马突触的突触前分化。突触后 CAM NGL-3（别名，Lrrc4b 基因产物）和 Neuroligin 通过与其各自的突触前结合 CAM LAR（别名，Ptprf 基因产物）和 neurexin 反式相互作用诱导突触前分化。 NGL-3（而不是 Neuroligin）的这种活性依赖于 afadin，但不依赖于 afadin 结合的突触前 CAM nectin-1。结合 afadin 的突触后 CAM nectin-3 不诱导突触前分化。免疫荧光和免疫电子显微镜分析表明，afadin 主要位于苔藓纤维突触的粘附点连接处，但部分位于突触连接处。已知与 LAR 结合的 β-连环蛋白和 γ-连环蛋白与来自小鼠脑裂解物的阿法丁进行免疫共沉淀。这些结果表明，afadin 以不依赖 nectin-1 的方式与 β-catenin 和 γ-catenin 协同参与 NGL-3-LAR 系统诱导的海马神经元突触前分化。
A hippocampal mossy fiber synapse, which is implicated in learning and memory, has a complex structure. We have previously shown using afadin-deficient mice that afadin plays multiple roles in the structural and functional differentiations of this synapse. We investigated here using a co-culture system with cultured hippocampal neurons and non-neuronal COS-7 cells expressing synaptogenic cell adhesion molecules (CAMs) whether afadin is involved in the presynaptic differentiation of hippocampal synapses. Postsynaptic CAMs NGL-3 (alias, a Lrrc4b gene product) and neuroligin induced presynaptic differentiation by trans-interacting with their respective presynaptic binding CAMs LAR (alias, a Ptprf gene product) and neurexin. This activity of NGL-3, but not neuroligin, was dependent on afadin, but not the afadin-binding presynaptic CAM nectin-1. The afadin-binding postsynaptic CAM nectin-3 did not induce presynaptic differentiation. Immunofluorescence and immunoelectron microscopy analyses showed that afadin was localized mainly at puncta adherentia junctions, but partly at synaptic junctions, of the mossy fiber synapse. beta-Catenin and gamma-catenin known to bind to LAR were co-immunoprecipitated with afadin from the lysate of mouse brain. These results suggest that afadin is involved in the NGL-3-LAR system-induced presynaptic differentiation of hippocampal neurons cooperatively with beta-catenin and gamma-catenin in a nectin-1-independent manner.