Sugimura Kaoru, Yamamoto Misato, Niwa Ryusuke, Satoh Daisuke, Goto Satoshi, Taniguchi Misako, Hayashi Shigeo, Uemura Tadashi
Department of Molecular Genetics, The Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan.
J Neurosci. 2003 May 1;23(9):3752-60. doi: 10.1523/JNEUROSCI.23-09-03752.2003.
Little has been understood about the underlying mechanisms that generate the morphological diversity of dendritic trees. Dendritic arborization neurons in Drosophila provide an excellent model system to tackle this question, and they are classified into classes I-IV in order of increasing arbor complexity. Here we have developed transgenic green fluorescent protein markers for class I or class IV cells, which allowed time-lapse recordings of dendritic birth in the embryo, its maturation processes in the larva, and lesion-induced reactions. The two classes used distinct strategies of dendritic emergence from the cell body and branching, which contributed to differences in their basic arbor patterns. In contrast to the class I cells examined, one cell of class IV, which was a focus in this study, continued to elaborate branches throughout larval stages, and it was much more capable of responding to the severing of branches. We also investigated the cellular basis of field formation between adjacent class IV cells. Our results support the fact that class-specific inhibitory interaction is necessary and sufficient for tiling and confirmed that this intercellular communication was at work at individual dendrodendritic interfaces. Finally, this inhibitory signaling appeared to play a central role when arbors of adjacent cells started meeting midway between the cells and until the body wall became partitioned into abutting, minimal-overlapping territories.
关于产生树突状树突形态多样性的潜在机制，人们了解甚少。果蝇中的树突状分支神经元为解决这个问题提供了一个极好的模型系统，它们按照树突复杂性增加的顺序被分为I-IV类。在这里，我们开发了用于I类或IV类细胞的转基因绿色荧光蛋白标记物，这使得我们能够对胚胎中树突的产生、幼虫中树突的成熟过程以及损伤诱导反应进行延时记录。这两类细胞从细胞体出现树突和分支的策略不同，这导致了它们基本树突模式的差异。与所研究的I类细胞不同，本研究重点关注的一个IV类细胞在整个幼虫阶段持续形成分支，并且对分支切断的反应能力更强。我们还研究了相邻IV类细胞之间形成区域的细胞基础。我们的结果支持这样一个事实，即特定类别的抑制性相互作用对于平铺是必要且充分的，并证实这种细胞间通讯在单个树突-树突界面起作用。最后，当相邻细胞的树突在细胞之间的中途开始相遇，直到体壁被分隔成相邻的、最小重叠的区域时，这种抑制信号似乎起着核心作用。
