Institut für Genetik, Heinrich-Heine-Universität Düsseldorf, Universitätsstrasse1, 40225, Düsseldorf, Germany.
J Cell Sci. 2012 Feb 1;125(Pt 3):763-76. doi: 10.1242/jcs.097261.
Recent work indicates that defects in late phases of the endosomal pathway caused by loss of function of the tumour suppressor gene lethal (2) giant discs (lgd) or the function of the ESCRT complexes I-III result in the ligand-independent activation of the Notch pathway in all imaginal disc cells in Drosophila melanogaster. lgd encodes a member of an uncharacterised protein family, whose members contain one C2 domain and four repeats of the DM14 domain. The function of the DM14 domain is unknown. We here report a detailed structure-function analysis of Lgd protein, which reveals that the DM14 domains are essential for the function of Lgd and act in a redundant manner. Moreover, our analysis indicates that the DM14 domain provides the specific function, whereas the C2 domain is required for the subcellular location of Lgd. We found that Lgd interacts directly with the ESCRT-III subunit Shrub through the DM14 domains. The interaction is required for the function of Shrub, indicating that Lgd contributes to the function of the ESCRT-III complex. Furthermore, our genetic studies indicate that the activation of Notch in ESCRT and lgd mutant cells occurs in a different manner and that the activity of Shrub and other ESCRT components are required for the activation of Notch in lgd mutant cells.
最近的研究工作表明，肿瘤抑制基因 lethal (2) giant discs (lgd) 或 ESCRT 复合物 I-III 的功能丧失导致内体途径晚期阶段的缺陷，从而导致果蝇所有 imaginal disc 细胞中配体非依赖性的 Notch 途径激活。lgd 编码一个未被表征的蛋白家族的成员，其成员包含一个 C2 结构域和四个 DM14 结构域的重复。DM14 结构域的功能未知。我们在这里报告了 Lgd 蛋白的详细结构-功能分析，结果表明 DM14 结构域对于 Lgd 的功能是必需的，并且以冗余的方式发挥作用。此外，我们的分析表明，DM14 结构域提供了特定的功能，而 C2 结构域是 Lgd 亚细胞定位所必需的。我们发现 Lgd 通过 DM14 结构域直接与 ESCRT-III 亚基 Shrub 相互作用。这种相互作用是 Shrub 功能所必需的，表明 Lgd 有助于 ESCRT-III 复合物的功能。此外，我们的遗传研究表明，ESCRT 和 lgd 突变细胞中 Notch 的激活以不同的方式发生，并且 Shrub 和其他 ESCRT 成分的活性对于 lgd 突变细胞中 Notch 的激活是必需的。
