Institute of Life Sciences, Key Laboratory of Developmental Genes and Human Disease, Southeast University, 2 Sipailou Road, Nanjing 210096, China.
Institute of Life Sciences, Key Laboratory of Developmental Genes and Human Disease, Southeast University, 2 Sipailou Road, Nanjing 210096, China; Co-innovation Center of Neuroregeneration, Nantong University, Nantong 226001, China.
Dev Cell. 2017 Apr 10;41(1):94-106.e4. doi: 10.1016/j.devcel.2017.03.004. Epub 2017 Mar 30.
Columnar restriction of neurites is critical for forming nonoverlapping receptive fields and preserving spatial sensory information from the periphery in both vertebrate and invertebrate nervous systems, but the underlying molecular mechanisms remain largely unknown. Here, we demonstrate that Drosophila homolog of α-neurexin (DNrx) plays an essential role in columnar restriction during L4 axon branching. Depletion of DNrx from L4 neurons resulted in misprojection of L4 axonal branches into neighboring columns due to impaired ephrin clustering. The proper ephrin clustering requires its interaction with the intracellular region of DNrx. Furthermore, we find that Drosophila neuroligin 4 (DNlg4) in Tm2 neurons binds to DNrx and initiates DNrx clustering in L4 neurons, which subsequently induces ephrin clustering. Our study demonstrates that DNrx promotes ephrin clustering and reveals that ephrin/Eph signaling from adjacent L4 neurons restricts axonal branches of L4 neurons in columns.
轴突分支的柱状限制对于形成不重叠的感受野和在脊椎动物和无脊椎动物神经系统中保留来自外围的空间感觉信息至关重要，但潜在的分子机制在很大程度上仍然未知。在这里，我们证明果蝇α-神经连接蛋白（DNrx）同源物在 L4 轴突分支过程中的柱状限制中发挥重要作用。由于 Ephrin 聚类受损，从 L4 神经元中耗尽 DNRx 会导致 L4 轴突分支错误投射到相邻的柱中。适当的 Ephrin 聚类需要其与 DNRx 的细胞内区域相互作用。此外，我们发现 Tm2 神经元中的果蝇神经连接蛋白 4（DNlg4）与 DNRx 结合，并在 L4 神经元中启动 DNRx 聚类，随后诱导 Ephrin 聚类。我们的研究表明 DNRx 促进 Ephrin 聚类，并揭示来自相邻 L4 神经元的 Ephrin/Eph 信号从柱状限制 L4 神经元的轴突分支。
