Localized FGF-receptor signaling controls differentiation of wrapping glial cells of Drosophila

有效的神经传导需要神经胶质细胞过程对轴突的绝缘。无脊椎动物，如果蝇，表现出轴突周围神经胶质膜的相对简单的延伸，类似于哺乳动物外周神经系统中由许旺细胞形成的Remak纤维。在tthis applicaction的框架下，我们希望解开神经胶质细胞分化的分子途径，使用发育中的果蝇视觉系统作为模型。在这里，包裹的胶质细胞首先沿着光感受器轴突束形成薄突起，然后包裹整个轴突束。这种分化是由成纤维细胞生长因子（FGF）信号传导控制的。FGF受体在神经元-神经胶质界面沿着感光轴突束的整个长度表达，并被轴突分泌的FGF激活。这表明FGF受体的局部活性对于触发轴突束周围的神经胶质膜生长是重要的。初步数据表明，额外的跨膜蛋白是需要正常分化的包裹神经胶质细胞。我们将确定这些因素，并解决的分子机制，直接神经胶质细胞生长周围的轴突。

Efficient neuronal conductance requires insulation of axons by glial cell processes. Inver-tebrates, such as Drosophila, show a relatively simple extension of glial membranes around the axons, resembling Remak fibers formed by Schwann cells in the mammalian peripheral nervous system. In the framework of tthis appliaction we want to unravel the molecular pathways underlying glial differentiation using the developing Drosophila visual system as a model. Here the wrapping glial cells first form thin processes along photore-ceptor axon fascicles to then ensheath the entire axon bundle. This differentiation is con-trolled by fibroblast growth factor (FGF)-signaling. The FGF-receptor is expressed at the neuron-glia interface along the entire length of the photoreceptor axon fascicle and is acti-vated by axonally secreted FGF. This suggests that localized activity of the FGF-receptor is important to trigger glial membrane growth around the axonal fascicle. Preliminary data suggest that additional transmembrane proteins are required for normal differentiation of the wrapping glia. We will identify these factors and address the molecular mechanisms that direct glial growth around the axon.