Novel level of signalling control in the JAK/STAT pathway revealed by in situ visualisation of protein-protein interaction during Drosophila development
Novel level of signalling control in the JAK/STAT pathway revealed by in situ visualisation of protein-protein interaction during Drosophila development
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DOI：
10.1242/dev.00535
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发表时间：
2003-07-01
期刊：
影响因子：
4.6
通讯作者：
Hombría, JCG
中科院分区：
文献类型：
--
作者：
Brown, S;Hu, N;Hombría, JCG
人们普遍认为，大多数信号通路的激活是由配体受体二聚化诱导的。这一观点在一些脊椎动物JAK/STAT通路的细胞因子受体中受到了挑战。在这里，我们研究了JAK/STAT通路的果蝇受体DOME是否可以二聚化，以及二聚化是否依赖于配体。为了分析DOME同质二聚化，我们应用了β -半乳糖互补技术，该技术允许原位检测蛋白质相互作用。这项技术以前曾用于细胞培养，但这是第一次应用于整个胚胎。我们表明，这种技术，我们更名为betalue-betalau技术，可用于检测发育中的果蝇胚胎中的DOME同二聚化。尽管DOME普遍表达，但二聚化是发育调控的。我们研究了在配体存在或不存在的情况下DOME二聚化的状态，并表明DOME二聚化不是配体诱导的，这表明与配体无关的细胞因子受体二聚化是整个门的保守特征。我们通过比较异位配体在受体二聚化或不二聚化的细胞中表达的影响，进一步分析了配体独立受体二聚化的功能意义。我们发现配体表达只能激活STAT下游靶标或影响受体二聚化的细胞中的胚胎发育。这些结果提示了一种模型，其中JAK/STAT受体的非配体二聚化赋予细胞在配体接受之前激活该途径的能力。因此，诱导果蝇JAK/STAT信号通路的能力可以通过在配体结合之前控制受体二聚化来调节。这些结果揭示了JAK/STAT信号调节的新水平，也可能适用于脊椎动物。
It is commonly accepted that activation of most signalling pathways is induced by ligand receptor dimerisation. This belief has been challenged for some vertebrate cytokine receptors of the JAK/STAT pathway. Here we study whether DOME, the Drosophila receptor of the JAK/STAT pathway, can dimerise and if the dimerisation is ligand-dependent. To analyse DOME homo-dimerisation, we have applied a beta-gal complementation technique that allows the detection of protein interactions in situ. This technique has been used previously in cell culture but this is the first time that it has been applied to whole embryos. We show that this technique, which we rename betalue-betalau technique, can be used to detect DOME homo-dimerisation in Drosophila developing embryos. Despite DOME being ubiquitously expressed, dimerisation is developmentally regulated. We investigate the state of DOME dimerisation in the presence or absence of ligand and show that DOME dimerisation is not ligand-induced, indicating that ligand independent cytokine receptor dimerisation is a conserved feature across phyla. We have further analysed the functional significance of ligand-independent receptor dimerisation by comparing the effects of ectopic ligand expression in cells in which the receptor is, or is not, dimerised. We show that ligand expression can only activate STAT downstream targets or affect embryo development in cells in which the receptor is dimerised. These results suggest a model in which ligand-independent dimerisation of the JAK/STAT receptor confers cells with competence to activate the pathway prior to ligand reception. Thus, competence to induce the JAK/STAT signalling pathway in Drosophila can be regulated by controlling receptor dimerisation prior to ligand binding. These results reveal a novel level of JAK/STAT signalling regulation that could also apply to vertebrates.