Wan H I, DiAntonio A, Fetter R D, Bergstrom K, Strauss R, Goodman C S
Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley 94720, USA.
Neuron. 2000 May;26(2):313-29. doi: 10.1016/s0896-6273(00)81166-6.
The formation, stabilization, and growth of synaptic connections are dynamic and highly regulated processes. The glutamatergic neuromuscular junction (NMJ) in Drosophila grows new boutons and branches throughout larval development. A primary walking behavior screen followed by a secondary anatomical screen led to the identification of the highwire (hiw) gene. In hiw mutants, the specificity of motor axon pathfinding and synapse formation appears normal. However, NMJ synapses grow exuberantly and are greatly expanded in both the number of boutons and the extent and length of branches. These synapses appear normal ultrastructurally but have reduced quantal content physiologically. hiw encodes a large protein found at presynaptic terminals. Within presynaptic terminals, HIW is localized to the periactive zone surrounding active zones; Fasciclin II (Fas II), which also controls synaptic growth, is found at the same location.
突触连接的形成、稳定和生长是动态且受到高度调控的过程。果蝇中的谷氨酸能神经肌肉接头（NMJ）在整个幼虫发育过程中会生长出新的突触小体和分支。通过一次主要的行走行为筛选以及随后的二次解剖学筛选，鉴定出了高丝氨酸（hiw）基因。在hiw突变体中，运动轴突寻路和突触形成的特异性看起来是正常的。然而，NMJ突触过度生长，并且在突触小体数量以及分支的范围和长度方面都大幅扩展。这些突触在超微结构上看起来正常，但在生理上量子含量减少。hiw编码一种存在于突触前末端的大蛋白。在突触前末端内，HIW定位于围绕活性区的活性区周围区域；同样控制突触生长的 fasciclin II（Fas II）也位于同一位置。
