Pack-Chung Eunju, Kurshan Peri T, Dickman Dion K, Schwarz Thomas L
Program in Neurobiology, Children's Hospital, 300 Longwood Avenue, Boston, Massachusetts 02115, USA.
Nat Neurosci. 2007 Aug;10(8):980-9. doi: 10.1038/nn1936. Epub 2007 Jul 22.
The morphological transition of growth cones to synaptic boutons characterizes synaptogenesis. Here we have isolated mutations in immaculate connections (imac; CG8566), a previously uncharacterized Drosophila gene encoding a member of the Kinesin-3 family. Whereas earlier studies in Drosophila implicated Kinesin-1 in transporting synaptic vesicle precursors, we find that Imac is essential for this transport. An unexpected feature of imac mutants is the failure of synaptic boutons to form. Motor neurons lacking imac properly target to muscles but remain within target fields as thin processes, a structure that is distinct from either growth cones or mature terminals. Few active zones form at these endings. We show that the arrest of synaptogenesis is not a secondary consequence of the absence of transmission. Our data thus indicate that Imac transports components required for synaptic maturation and provide insight into presynaptic maturation as a process that can be differentiated from axon outgrowth and targeting.
生长锥向突触小体的形态转变是突触形成的特征。在这里，我们分离出了“完美连接”（imac；CG8566）基因的突变，该基因是果蝇中一个此前未被鉴定的基因，编码驱动蛋白-3家族的一个成员。虽然此前在果蝇中的研究表明驱动蛋白-1参与突触小泡前体的运输，但我们发现Imac对于这种运输至关重要。imac突变体的一个意外特征是突触小体无法形成。缺乏imac的运动神经元能够正确地靶向肌肉，但作为细的突起保留在靶区域内，这种结构既不同于生长锥也不同于成熟的终末。在这些末端几乎没有活性区形成。我们表明突触形成的停滞不是缺乏传递的次要后果。因此，我们的数据表明Imac运输突触成熟所需的成分，并为突触前成熟这一可与轴突生长和靶向区分开来的过程提供了见解。
