Functional domains and sub-cellular distribution of the Hedgehog transducing protein Smoothened in Drosophila
Functional domains and sub-cellular distribution of the Hedgehog transducing protein Smoothened in Drosophila
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DOI：
10.1016/j.mod.2004.04.015
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发表时间：
2004-06-01
影响因子：
2.6
通讯作者：
Ingham, PW
中科院分区：
文献类型：
--
作者：
Nakano, Y;Nystedt, S;Ingham, PW
刺猬信号通路在正常动物发育过程中反复部署，其不适当的活动与人类各种肿瘤有关。蛇形蛋白平滑（Smo）是细胞响应Hedeghog （Hh）信号所必需的；致癌形式的Smo已从人基底细胞癌中分离出来。尽管与配体结合的g蛋白偶联受体有相似之处，Smo活性的分子基础及其调控尚不清楚。在无应答的细胞中，Smo被另一种多通膜跨越蛋白Ptc的活性抑制，该蛋白作为Hh受体。在果蝇中，Hh与Ptc的结合已被证明会导致Smo蛋白磷酸化的积累，并伴随Ci转录因子激活形式的稳定。在这里，我们确定了Smo活性所必需的结构域，并研究了野生型蛋白在体内的亚细胞分布。我们发现，蛋白质的氨基端和羧基端近膜区域的缺失导致正常Smo活性的丧失。利用绿色荧光蛋白（GFP）和辣根过氧化物酶融合蛋白，我们发现Smo在Re活性被Hh消除的细胞的质膜中积累，但在Re活性的细胞中，Smo被靶向降解途径。我们进一步证明Smo积累可能是Hh信号转导的原因，而不是结果。2004爱思唯尔爱尔兰有限公司版权所有。
The Hedgehog signalling pathway is deployed repeatedly during normal animal development and its inappropriate activity is associated with various tumours in human. The serpentine protein Smoothened (Smo) is essential for cells to respond to the Hedeghog (Hh) signal; oncogenic forms of Smo have been isolated from human basal cell carcinomas. Despite similarities with ligand binding G-protein coupled receptors, the molecular basis of Smo activity and its regulation remains unclear. In non-responding cells, Smo is suppressed by the activity of another multipass membrane spanning protein Ptc, which acts as the Hh receptor. In Drosophila, binding of Hh to Ptc has been shown to cause an accumulation of phosphorylated Smo protein and a concomitant stabilisation of the activated form of the Ci transcription factor. Here, we identify domains essential for Smo activity and investigate the sub-cellular distribution of the wild type protein in vivo. We find that deletion of the amino terminus and the juxtamembrane region of the carboxy terminus of the protein result in the loss of normal Smo activity. Using Green Fluorescent Protein (GFP) and horseradish peroxidase fusion proteins we show that Smo accumulates in the plasma membrane of cells in which Re activity is abrogated by Hh but is targeted to the degradative pathway in cells where Re is active. We further demonstrate that Smo accumulation is likely to be a cause, rather than a consequence, of Hh signal transduction. (C) 2004 Elsevier Ireland Ltd. All rights reserved.