Genetic regions that interact with loss- and gain-of-function phenotypes of deltex implicate novel genes in Drosophila Notch signaling
Genetic regions that interact with loss- and gain-of-function phenotypes of deltex implicate novel genes in Drosophila Notch signaling
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DOI：
10.1007/s00438-004-1098-1
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发表时间：
2005-01
影响因子：
3.1
通讯作者：
Kazuya Hori;Takashi J. Fuwa;T. Seki;K. Matsuno
中科院分区：
文献类型：
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作者：
Kazuya Hori;Takashi J. Fuwa;T. Seki;K. Matsuno
Notch信号通路是一种进化保守的机制，它调节许多细胞的命运决定。deltex（dx）基因编码e3 -泛素连接酶，该连接酶与Notch蛋白的细胞内结构域结合，并以积极的方式调节Notch信号传导。然而，目前尚不清楚Dx是如何做到这一点的。我们产生了一个转基因系，GMR-dx，它在发育中的果蝇眼盘中过度表达。gmr -dxline显示糙眼表型，感光细胞（R3到R4）的特异性转化，以及小眼的旋转缺陷。这种表型在与adxloss-of-function突变体结合时被抑制，表明这是由于adxgain-of-function引起的。我们之前报道过Dx的过表达导致Notch在晚期核内体的稳定。在这里，我们发现Dx上的三个基序，一个与Notch结合的区域，一个富含脯氨酸的基序和一个RING-H2指，是这种稳定所必需的，尽管在这个实验中这些变异的相对活性并不总是与糙眼表型的严重程度相对应。为了鉴定Notch通路的新基因，我们测试了大量的染色体缺陷，以改变gmr -dxline的眼睛表型。鉴定出12个增强gmr -dx粗眼表型的基因组片段。为了评估这些相互作用的特异性，我们随后确定了这些缺失是否也与与dx，dx24的功能丧失突变相关的翅膀表型相互作用。基于全基因组信息的分析使我们得出结论，我们已经确定了两个新的基因座，其中可能包括参与dx介导的Notch信号传导的未表征基因。
The Notch signaling pathway is an evolutionarily conserved mechanism that regulates many cell fate decisions. Thedeltex(dx) gene encodes an E3-ubiquitin ligase that binds to the intracellular domain of the Notch protein and regulates Notch signaling in a positive manner. However, it is still not clear how Dx does this. We generated a transgenic line,GMR-dx, which overexpressesdxin the developingDrosophilaeye disc. TheGMR-dxline showed a rough-eye phenotype, specific transformation of a photoreceptor cell (R3 to R4), and a rotation defect in the ommatidia. This phenotype was suppressed in combination with adxloss-of-function mutant, indicating that it was due to adxgain-of-function. We previously reported that overexpression of Dx results in the stabilization of Notch in late endosomes. Here, we found that three motifs in Dx, a region that binds to Notch, a proline-rich motif and a RING-H2 finger, were required for this stabilization, although the relative activity of these variants in this assay did not always correspond to the severity of the rough-eye phenotype. In an attempt to identify novel genes of the Notch pathway, we tested a large collection of chromosomal deficiencies for the ability to modify the eye phenotypes of theGMR-dxline. Twelve genomic segments that enhanced the rough-eye phenotype ofGMR-dxwere identified. To evaluate the specificity of these interactions, we then determined whether the deletions also interacted with the wing phenotypes associated with a loss-of-function mutation ofdx,dx24. Analyses based on whole-genome information allowed us to conclude that we have identified two novel loci that probably include uncharacterized genes involved in Dx-mediated Notch signaling.