Hierarchical axon targeting of Drosophila olfactory receptor neurons specified by the proneural transcription factors Atonal and Amos
Hierarchical axon targeting of Drosophila olfactory receptor neurons specified by the proneural transcription factors Atonal and Amos
复制标题
原神经转录因子 Atonal 和 Amos 指定的果蝇嗅觉受体神经元的分层轴突靶向
作者：
Okumura;M.;Kato;T.;Miura;M. and Chihara;T.
感觉信息在大脑中以空间形式呈现，形成神经地图。有人认为轴突-轴突的相互作用对神经图谱的形成很重要；然而，其潜在机制尚未完全了解。我们使用果蝇的触角叶，大脑中的第一个嗅觉中心，作为研究神经图谱形成的模型。嗅觉受体神经元（orn）表达相同的气味受体，其轴突指向触角叶约50个肾小球中的一个肾小球。先前的研究表明，Atonal orn的轴突，由基本螺旋-环-螺旋（bHLH）转录因子Atonal指定，先锋天线瓣形成；然而，细节仍有待阐明。在这里，我们发现基因消融Atonal ORN会影响Amos ORN的天线叶结构和轴突靶向，Amos ORN是bHLH转录因子Amos指定的另一种ORN。在发育过程中，非国家性神经元先于阿莫斯神经元到达触角叶并形成轴突连接。我们还发现，特异性的n‐cadherin敲低会破坏整个触角叶的肾小球边界。我们的研究结果表明，非调性轴突具有先锋轴突的功能。因此，正确的轴突定位对于整个触角叶的形成至关重要。
Sensory information is spatially represented in the brain to form a neural map. It has been suggested that axon–axon interactions are important for neural map formation; however, the underlying mechanisms are not fully understood. We used theDrosophilaantennal lobe, the first olfactory center in the brain, as a model for studying neural map formation. Olfactory receptor neurons (ORNs) expressing the same odorant receptor target their axons to a single glomerulus out of approximately 50 glomeruli in the antennal lobe. Previous studies have showed that the axons of Atonal ORNs, specified by Atonal, a basic helix‐loop‐helix (bHLH) transcription factor, pioneer antennal lobe formation; however, the details remain to be elucidated. Here, we show that genetic ablation of Atonal ORNs affects antennal lobe structure and axon targeting of Amos ORNs, another type of ORN specified by the bHLH transcription factor Amos. During development, Atonal ORNs reach the antennal lobe and form the axon commissure before Amos ORNs. We also found thatN‐cadherinknockdown specifically in Atonal ORNs disrupts the glomerular boundary in the whole antennal lobe. Our results suggest that Atonal ORNs function as pioneer axons. Thus, correct axon targeting of Atonal ORNs is essential for formation of the whole antennal lobe.