Lattemann Marc, Zierau Ariane, Schulte Claus, Seidl Sascha, Kuhlmann Britta, Hummel Thomas
Institut für Neurobiologie, Universität Münster, Badestrasse 9, D-48149 Münster, Germany.
Neuron. 2007 Jan 18;53(2):169-84. doi: 10.1016/j.neuron.2006.12.024.
In the olfactory system of Drosophila, 50 functional classes of sensory receptor neurons (ORNs) project in a highly organized fashion into the CNS, where they sort out from one another and converge into distinct synaptic glomeruli. We identified the transmembrane molecule Semaphorin-1a (Sema-1a) as an essential component to ensure glomerulus-specific axon segregation. Removal of sema-1a in ORNs does not affect the pathfinding toward their target area but disrupts local axonal convergence into a single glomerulus, resulting in two distinct targeting phenotypes: axons either intermingle with adjacent ORN classes or segregate according to their odorant receptor identity into ectopic sites. Differential Sema-1a expression can be detected among neighboring glomeruli, and mosaic analyses show that sema-1a functions nonautonomously in ORN axon sorting. These findings provide insights into the mechanism by which afferent interactions lead to synaptic specificity in the olfactory system.
在果蝇的嗅觉系统中，50种功能类别的感觉受体神经元（ORN）以高度有组织的方式投射到中枢神经系统（CNS），在那里它们相互分离并汇聚到不同的突触小球中。我们确定跨膜分子信号素-1a（Sema-1a）是确保小球特异性轴突分离的关键成分。在ORN中去除sema-1a不会影响其向目标区域的路径寻找，但会破坏局部轴突汇聚到单个小球中，从而产生两种不同的靶向表型：轴突要么与相邻的ORN类别相互混合，要么根据其气味受体身份分离到异位位点。在相邻的小球之间可以检测到Sema-1a的差异表达，并且镶嵌分析表明sema-1a在ORN轴突分选过程中发挥非自主功能。这些发现为传入相互作用导致嗅觉系统中突触特异性的机制提供了见解。
