Semaphorin 2a secreted by oenocytes signals through plexin B and plexin A to guide sensory axons in the Drosophila embryo
Semaphorin 2a secreted by oenocytes signals through plexin B and plexin A to guide sensory axons in the Drosophila embryo
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DOI：
10.1016/j.ydbio.2006.10.015
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发表时间：
2007-02-15
影响因子：
2.7
通讯作者：
Whitington, Paul M.
中科院分区：
文献类型：
--
作者：
Bates, Karen E.;Whitington, Paul M.
信号蛋白基因家族已被证明在脊椎动物和无脊椎动物的轴突引导中发挥重要作用。在果蝇中存在跨膜（Sema1a, Sema1b, Sema5c）和分泌（Sema2a, Sema2b）形式的信号蛋白。两个Sema受体，丛蛋白（Plex） A和B，也已被确定。关于分泌信号素的轴突引导功能，包括其受体的身份，仍然存在许多问题。我们利用果蝇胚胎的良好特征的感觉系统来解决这些问题。我们在sema2a功能丧失突变体中发现了新的感觉轴突缺陷，其中特定轴突错误投射并遵循不适当的途径进入中枢神经系统。plexB功能丧失突变体表现出与sema2a突变体相似的表型，sema2a与plexB基因相互作用，支持sema2a通过plexB受体发出信号的假设。Sema2a蛋白由卵母细胞表达，卵母细胞是胚胎外侧区域的一群分泌细胞，通过在这些细胞中驱动Sema2a可以挽救Sema2a突变表型。卵巢细胞消融导致感觉轴突缺陷，类似sema2a突变表型。这些数据支持一个模型，即Sema2a虽然从卵泡细胞分泌，但以高度局部的方式起作用：它抑制感觉神经元细胞体的轴突延伸，但仅在与卵泡细胞直接接触的区域。英国皇家版权所有(c) 2006出版的爱思唯尔公司。版权所有。
The semaphorin gene family has been shown to play important roles in axonal guidance in both vertebrates and invertebrates. Both transmembrane (Sema1a, Sema1b, Sema5c) and secreted (Sema2a, Sema2b) forms of semaphorins exist in Drosophila. Two Sema receptors, plexins (Plex) A and B, have also been identified. Many questions remain concerning the axon guidance functions of the secreted semaphorins, including the identity of their receptors. We have used the well-characterized sensory system of the Drosophila embryo to address these problems. We find novel sensory axon defects in sema2a loss-of-function mutants in which particular axons misproject and follow inappropriate pathways to the CNS. plexB loss-of-function mutants show similar phenotypes to sema2a mutants and sema2a interacts genetically with plexB, supporting the hypothesis that Sema2a, signals through PlexB receptors. Sema2a protein is expressed by larval oenocytes, a cluster of secretory cells in the lateral region of the embryo and the sema2a mutant phenotype can be rescued by driving Sema2a in these cells. Ablation of oenocytes results in sensory axon defects similar to the sema2a mutant phenotype. These data support a model in which Sema2a, while being secreted from oenocytes, acts in a highly localized fashion: It represses axon extension from the sensory neuron cell body, but only in regions in direct contact with oenocytes. Crown Copyright (c) 2006 Published by Elsevier Inc. All rights reserved.