Cell-cell communications in neural circuit assembly

项目摘要 神经生物学中的一个关键问题是单个神经元如何精确地与每个神经元连接。 另一个在开发过程中形成功能电路。了解的机制 哺乳动物大脑中的神经回路组装可以提供对 人类大脑紊乱在哺乳动物的大脑中，平均每个神经元 与成千上万的其他神经元连接。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。 在此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）和病毒遗传操作， 使我们能够标记和遗传操纵特定的神经元细胞类型， 个体神经元，并研究在树突形态发生中起关键作用的基因， 轴突的靶向选择。具体来说，我们最近发现了两种细胞表面 表达于细胞中的蛋白质Teneurin-3（Ten 3）和Latrophilin-2（Lphn 2） 海马网络的互连节点中的互补模式， “Ten 3 → Ten 3，Lphn 2 → Lphn 2”连通性规则。我们已经证明，Lphn 2作为一个 Ten 3作为亲异性排斥配体，Ten 3作为亲同性吸引配体， Ten 3+近端CA 1轴突选择性靶向远端下托;同时， Ten 3作为一个排斥配体直接Lphn 2+轴突近端下托。我们有 我还开发了一种方法，使我们能够用精致的蛋白质组来描绘细胞表面蛋白质组。 灵敏度和时空控制。 在本提案中，我们将扩展这两项最新进展。具体来说，我们将 研究Ten 3和Lphn 2是否指示多个节点中的布线特异性。 扩展的海马网络和其他大脑区域，Ten 3-Lphn 2如何相互作用 导致轴突排斥，以及G蛋白信号是否对Lphn 2的作用至关重要 作为受体或配体。作为对Ten 3和Lphn 2深入研究的补充，我们 将使用我们的细胞表面蛋白质组学分析方法，广泛调查细胞的变化， 从发育到成熟的神经元，并确定新的细胞表面蛋白质组， 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.