The F-actin-microtubule crosslinker Shot is a platform for Krasavietz-mediated translational regulation of midline axon repulsion
The F-actin-microtubule crosslinker Shot is a platform for Krasavietz-mediated translational regulation of midline axon repulsion
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DOI：
10.1242/dev.02842
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发表时间：
2007-05-01
期刊：
影响因子：
4.6
通讯作者：
Lee, Seungbok
中科院分区：
文献类型：
--
作者：
Lee, Seongsoo;Nahm, Minyeop;Lee, Seungbok
轴突延伸和引导需要 F-肌动蛋白和微管的协调组装以及受调控的翻译。编码引导蛋白的 mRNA 的翻译如何与细胞骨架组装的速度密切相关的分子基础尚不清楚。先前的研究表明，F-肌动蛋白 - 微管交联剂短停（Shot）是果蝇胚胎中运动和感觉轴突延伸所必需的。在这里，我们提供了生化和遗传学证据，证明 Shot 与一种新型翻译抑制剂 Krasavietz（Kra，Exba）一起发挥作用，引导纵向 CNS 轴突远离中线。 Kra 直接结合 Shot 的 C 末端，这种相互作用是 Shot 活性支持中线轴突排斥所必需的。 shot 和 kra 突变导致弱的机器人表型，并协同影响中枢神经系统轴突的中线回避。我们还表明，shot 和 kra 显着提高了 split 或 robo 杂合胚胎中中线交叉的频率，并且在 kra 突变胚胎中，一些 Robo 阳性轴突异位穿过通常表达排斥性 Slit 的中线。最后，我们证明 Kra 还与翻译起始因子 eIF2 beta 相互作用并抑制体外翻译。总之，这些数据表明 Kra 介导的翻译调节在中线轴突排斥中发挥重要作用，并且 Shot 充当翻译调节和细胞骨架重组之间的直接物理联系。
Axon extension and guidance require a coordinated assembly of F-actin and microtubules as well as regulated translation. The molecular basis of how the translation of mRNAs encoding guidance proteins could be closely tied to the pace of cytoskeletal assembly is poorly understood. Previous studies have shown that the F-actin - microtubule crosslinker Short stop (Shot) is required for motor and sensory axon extension in the Drosophila embryo. Here, we provide biochemical and genetic evidence that Shot functions with a novel translation inhibitor, Krasavietz (Kra, Exba), to steer longitudinally directed CNS axons away from the midline. Kra binds directly to the C-terminus of Shot, and this interaction is required for the activity of Shot to support midline axon repulsion. shot and kra mutations lead to weak robo-like phenotypes, and synergistically affect midline avoidance of CNS axons. We also show that shot and kra dominantly enhance the frequency of midline crossovers in embryos heterozygous for slit or robo, and that in kra mutant embryos, some Robo-positive axons ectopically cross the midline that normally expresses the repellent Slit. Finally, we demonstrate that Kra also interacts with the translation initiation factor eIF2 beta and inhibits translation in vitro. Together, these data suggest that Kra-mediated translational regulation plays important roles in midline axon repulsion and that Shot functions as a direct physical link between translational regulation and cytoskeleton reorganization.