A novel Dlg isoform and identification of its proteins

描述(申请人提供)：果蝇是研究动物发育和癌症形成的极佳模式生物，因为所涉及的关键蛋白质在所有动物中都是保守的，而果蝇提供了巨大的实验优势。Discs-Large(DLG)蛋白家族最初被鉴定为果蝇的肿瘤抑制因子，后来又鉴定出多种哺乳动物的DLG同源物。目前已知它们在果蝇顶端-基底细胞极性的建立、细胞-细胞接触的形成以及在细胞膜表面组装大的蛋白质复合体方面发挥着关键作用。在哺乳动物中，DLG同源物之一hDlg的截断会导致头面部畸形发育和围产儿死亡。然而，DLG的潜在机制在很大程度上仍不清楚。 苍蝇基因组序列的完成和许多新的DLG cDNA的恢复最近揭示了以前未被注意到的多种DLG亚型的存在。首席研究人员发现，其中一个DLG亚型，DLG-75，可能执行之前分配给原型DLG-A的许多DLG功能。为了了解DLG-75的功能，她将使用两种方法寻找DLG-75的相互作用蛋白质。首先，将进行一系列强大的基因筛查，以选择调节DLG-75活性或水平的基因。其次，能够与DLG-75物理相互作用的蛋白质将通过双杂交筛选进行鉴定。这两种筛查都简单有效，执行时间相对较短。 考虑到DLG-75相互作用蛋白STBM对小鼠神经管的形成是必不可少的，从这些筛选中识别DLG-75相互作用蛋白将极大地有助于理解DLG和STBM在苍蝇和人类的生长控制、细胞极性和发育中的作用机制。

DESCRIPTION (provided by applicant): Drosophila melanogaster is an excellent model organism to study animal development as well as formation of cancer because the critical proteins involved are conserved in all animals, and flies offer tremendous experimental advantages. The Discs-Large (Dlg) family of proteins was originally identified as a tumor suppressor in flies, and multiple mammalian Dlg homologs were subsequently identified. They are now known to play critical roles in establishing apical-basal cell polarity, formation of cell-cell contacts, and assembly of large protein complexes on the cytoplasmic faces of membranes in flies. In mammals, truncation in one of Dlg homologs, hDlg, results in craniofacial dysmorphogenesis and perinatal death. However, the underlying mechanism of Dlg is still largely unknown. Completion of fly genome sequence and the recovery of many new dlg cDNAs recently revealed the presence of multiple Dlg isoforms that were previously unnoticed. The principal investigator discovered that one of those multiple Dlg isoforms, Dlg-75, may carry out many of Dlg functions previously assigned to the prototype Dlg-A. To understand the function of Dlg-75, she will search for the interacting proteins of Dlg-75 using two approaches. First, a set of powerful genetic screens will be carried out to select for the genes modulating the activity or level of Dlg-75. Second, proteins that are capable of physically interacting with Dlg-75 will be identified with two-hybrid screen. Both screens are simple and effective and take relatively short time to carry out. Considering that Strabismus (Stbm), a Dlg-75-interacting protein, is essential for neural tube formation of mice, identification of Dlg-75-interacting proteins from these screens will greatly facilitate understanding on the mechanism of Dlg and Stbm in growth control, cell polarity, and development in both flies and humans.