Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305.
Department of Biology, Stanford University, Stanford, CA 94305.
Proc Natl Acad Sci U S A. 2017 Jul 18;114(29):7505-7512. doi: 10.1073/pnas.1706533114. Epub 2017 Jul 3.
The formation of complex but highly organized neural circuits requires interactions between neurons and glia. During the assembly of the olfactory circuit, 50 olfactory receptor neuron (ORN) classes and 50 projection neuron (PN) classes form synaptic connections in 50 glomerular compartments in the antennal lobe, each of which represents a discrete olfactory information-processing channel. Each compartment is separated from the adjacent compartments by membranous processes from ensheathing glia. Here we show that Thisbe, an FGF released from olfactory neurons, particularly from local interneurons, instructs ensheathing glia to wrap each glomerulus. The Heartless FGF receptor acts cell-autonomously in ensheathing glia to regulate process extension so as to insulate each neuropil compartment. Overexpressing Thisbe in ORNs or PNs causes overwrapping of the glomeruli their axons or dendrites target. Failure to establish the FGF-dependent glia structure disrupts precise ORN axon targeting and discrete glomerular formation.
复杂而高度组织化的神经回路的形成需要神经元和神经胶质之间的相互作用。在嗅觉回路的组装过程中，50 种嗅觉受体神经元 (ORN) 类和 50 种投射神经元 (PN) 类在触角叶的 50 个肾小球隔室中形成突触连接，每个隔室代表一个离散的嗅觉信息处理通道。每个隔室都通过鞘状胶质细胞的膜状突起与相邻隔室隔开。在这里，我们发现，嗅神经元（特别是局部中间神经元）释放的 FGF 因子 Thisbe 指导鞘状胶质细胞包裹每个肾小球。Heartless FGF 受体在鞘状胶质细胞中自主发挥作用，调节突起的延伸，从而隔离每个神经原纤维隔室。在 ORNs 或 PNs 中过度表达 Thisbe 会导致其轴突或树突靶向的肾小球过度包裹。未能建立依赖 FGF 的神经胶质结构会破坏精确的 ORN 轴突靶向和离散的肾小球形成。
