Nucleocytoplasmic shuttling mediates the dynamic maintenance of nuclear Dorsal levels during Drosophila embryogenesis
Nucleocytoplasmic shuttling mediates the dynamic maintenance of nuclear Dorsal levels during Drosophila embryogenesis
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DOI：
10.1242/dev.010934
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发表时间：
2007-12-01
期刊：
影响因子：
4.6
通讯作者：
Lippincott-Schwartz, Jennifer
中科院分区：
文献类型：
--
作者：
DeLotto, Robert;DeLotto, Yvonne;Lippincott-Schwartz, Jennifer
在果蝇中，NF-kappa B/REL家族转录因子Dorsal从细胞质向细胞核重新分布，在胚胎的背腹侧轴上形成浓度梯度。利用实时成像技术结合表达嵌合Dorsal- gfp的胚胎，我们证明了Dorsal从细胞质到细胞核的再分配是一个极其动态的过程。间期各核背侧浓度随时间连续变化。虽然背侧似乎主要局限于腹侧核，但它在包括背侧核在内的所有核中活跃穿梭。核输出被leptomycin B阻断，leptomycin B是一种有效的出口蛋白1 （CRM1）介导的核输出抑制剂。我们已经开发了一种新的体内实验，揭示了在背侧44个氨基酸的羧基末端存在一个功能性的富含亮氨酸的核输出信号。我们还发现，Dorsal的扩散部分局限于单个突触核周围的细胞质岛。提出了一个模型，其中背侧梯度的产生和维持是一个主动过程的结果，该过程涉及有限的远程扩散和核进口与核出口的平衡。
In Drosophila, the NF-kappa B/REL family transcription factor, Dorsal, redistributes from the cytoplasm to nuclei, forming a concentration gradient across the dorsoventral axis of the embryo. Using live imaging techniques in conjunction with embryos expressing a chimeric Dorsal-GFP, we demonstrate that the redistribution of Dorsal from cytoplasm to nucleus is an extremely dynamic process. Nuclear Dorsal concentration changes continuously over time in all nuclei during interphase. While Dorsal appears to be nuclearly localized primarily in ventral nuclei, it is actively shuttling into and out of all nuclei, including nuclei on the dorsal side. Nuclear export is blocked by leptomycin B, a potent inhibitor of Exportin 1 (CRM1)-mediated nuclear export. We have developed a novel in vivo assay revealing the presence of a functional leucine-rich nuclear export signal within the carboxyterminal 44 amino acids of Dorsal. We also find that diffusion of Dorsal is partially constrained to cytoplasmic islands surrounding individual syncitial nuclei. A model is proposed in which the generation and maintenance of the Dorsal gradient is a consequence of an active process involving both restricted long-range diffusion and the balancing of nuclear import with nuclear export.