Department of Biology, Indiana University, Bloomington, IN 47405, United States.
Department of Biology, Indiana University, Bloomington, IN 47405, United States.
Dev Biol. 2014 Jun 15;390(2):170-80. doi: 10.1016/j.ydbio.2014.03.012. Epub 2014 Mar 29.
Sine Oculis (So), the founding member of the SIX family of homeobox transcription factors, binds to sequence specific DNA elements and regulates transcription of downstream target genes. It does so, in part, through the formation of distinct biochemical complexes with Eyes Absent (Eya) and Groucho (Gro). While these complexes play significant roles during development, they do not account for all So-dependent activities in Drosophila. It is thought that additional So-containing complexes make important contributions as well. This contention is supported by the identification of nearly two-dozen additional proteins that complex with So. However, very little is known about the roles that these additional complexes play in development. In this report we have used yeast two-hybrid screens and co-immunoprecipitation assays from Kc167 cells to identify a biochemical complex consisting of So and Fl(2)d, the Drosophila homolog of human Wilms׳ Tumor 1-Associating Protein (WTAP). We show that Fl(2)d protein is distributed throughout the entire eye-antennal imaginal disc and that loss-of-function mutations lead to perturbations in retinal development. The eye defects are manifested behind the morphogenetic furrow and result in part from increased levels of the pan-neuronal RNA binding protein Embryonic Lethal Abnormal Vision (Elav) and the RUNX class transcription factor Lozenge (Lz). We also provide evidence that So and Fl(2)d interact genetically in the developing eye. Wilms׳ tumor-1 (WT1), a binding partner of WTAP, is required for normal eye formation in mammals and loss-of-function mutations are associated with some versions of retinoblastoma. In contrast, WTAP and its homologs have not been implicated in eye development. To our knowledge, the results presented in this report are the first description of a role for WTAP in the retina of any seeing animal.
Sine Oculis（So）是 SIX 家族同源盒转录因子的创始成员之一，它与序列特异性 DNA 元件结合，并调节下游靶基因的转录。它通过与 Eyes Absent（Eya）和 Groucho（Gro）形成独特的生化复合物来实现这一点。虽然这些复合物在发育过程中发挥着重要作用，但它们并不能解释果蝇中所有依赖 So 的活性。人们认为，额外的含有 So 的复合物也做出了重要贡献。这一论点得到了近二十几种与 So 相互作用的额外蛋白质的鉴定的支持。然而，人们对这些额外复合物在发育中的作用知之甚少。在本报告中，我们使用酵母双杂交筛选和 Kc167 细胞的共免疫沉淀测定，鉴定了一个由 So 和果蝇同源物 Fl(2)d 组成的生化复合物，Fl(2)d 是人类 Wilms' Tumor 1-Associating Protein（WTAP）的同源物。我们表明，Fl(2)d 蛋白分布在整个眼-触角 imaginal 盘，并且功能丧失突变导致视网膜发育异常。眼部缺陷出现在形态发生褶皱后面，部分原因是 pan-neuronal RNA 结合蛋白 Embryonic Lethal Abnormal Vision（Elav）和 RUNX 类转录因子 Lozenge（Lz）的水平升高。我们还提供了证据表明 So 和 Fl(2)d 在发育中的眼睛中存在遗传相互作用。WT1 是 WTAP 的结合伴侣，它在哺乳动物中是正常眼睛形成所必需的，功能丧失突变与某些类型的视网膜母细胞瘤有关。相比之下，WTAP 及其同源物尚未被牵连到眼睛发育中。据我们所知，本报告中提出的结果是 WTAP 在任何有视力的动物视网膜中的作用的第一个描述。
