Cell-cell communications in neural circuit assembly

项目总结 神经生物学中的一个关键问题是单个神经元如何准确地与 其他在发育过程中形成功能电路。了解以下机制： 哺乳动物大脑中的神经回路组装可能为揭示脑血管疾病的病因提供线索。 人类大脑紊乱。在哺乳动物的大脑中，每个神经元平均形成 与数以千计的其他神经元连接。这些复杂电路的组装 在神经发育的许多步骤中依赖于细胞间的通讯。 在这笔赠款的前三个周期中，我们开发了MADM等方法 (双标记镶嵌分析)和对小鼠的病毒遗传操作 允许我们标记和遗传操作特定的神经细胞类型，下至 单个神经元，并研究在树突形态发生和发育中起关键作用的基因。 轴突的靶点选择。具体地说，我们最近确定了两个细胞表面 Teneurin-3(Ten3)和LatroPhilin-2(Lphn2)，这些蛋白质在 海马网相互连接的节点中的互补模式如下 “Ten3→Ten3，Lphn2→Lphn2”连通性规则。我们已经证明了Lphn2作为一个 异亲排斥配体和Ten3作为亲异吸引配体直接 Ten3+近端CA1轴突选择性靶向远侧下丘脑；同时， Ten3作为排斥配体将Lphn2+轴突导向近侧下丘脑底。我们有 还开发了一种方法，使我们能够精确地描绘细胞表面蛋白质组 敏感度和时空控制。 在这项提案中，我们将对这两个最新进展进行扩展。具体来说，我们将 研究Ten3和Lphn2是否指示多个节点的连接特异性 扩展的海马网和其他脑区，Ten3-Lphn2如何相互作用 导致轴突排斥，以及G蛋白信号是否对Lphn2的S作用是必需的 作为受体或配体。作为对Ten3和Lphn2深入研究的补充，我们 将使用我们的细胞表面蛋白质组图谱方法来广泛调查细胞的变化- 从发育中的神经元到成熟神经元的表面蛋白质组，并鉴定新的细胞表面 调节树突形态发生和神经回路组装的蛋白质。

PROJECT SUMMARY A key question in neurobiology is how individual neurons precisely connect with each other to form functional circuits during development. Understanding the mechanisms of neural circuit assembly in the mammalian brain may provide insights into the etiology of human brain disorders. In the mammalian brain, each neuron on average forms connection with thousands of other neurons. The assembly of these complex circuits depends on cell-cell communication during many steps of neural development. In the previous three cycles of this grant, we have developed methods such as MADM (Mosaic Analysis with Double Markers) and viral-genetic manipulations in mice that allowed us to label and genetically manipulate specific neuron cell types, down to individual neurons, and study genes that play key roles in dendrite morphogenesis and target selection of axons. Specifically, we have recently identified two cell-surface proteins, Teneurin-3 (Ten3) and Latrophilin-2 (Lphn2), that are expressed in complementary patterns in the interconnected nodes of hippocampal network, following a “Ten3→Ten3, Lphn2→Lphn2” connectivity rule . We have shown that Lphn2 acts as a heterophilic repulsive ligand and Ten3 acts as a homophilic attractive ligand to direct Ten3+ proximal CA1 axons to selectively target to distal subiculum; at the same time, Ten3 acts as a repulsive ligand to direct Lphn2+ axons to proximal subiculum. We have also developed a method that allows us to profile cell-surface proteomes with exquisite sensitivity and spatiotemporal control. In this proposal, we will expand on both of these recent advances. Specifically, we will investigate whether Ten3 and Lphn2 instruct wiring specificity in multiple nodes of the extended hippocampal network and in other brain regions, how Ten3-Lphn2 interaction leads to axon repulsion, and whether G protein signaling is essential for Lphn2’s action as a receptor or a ligand. Complementary to the in-depth studies of Ten3 and Lphn2, we will use our cell-surface proteomic profiling methods to broadly survey changes of cell- surface proteomes from developing to mature neurons, and to identify new cell-surface proteins that regulate dendrite morphogenesis and neural circuit assembly.