Characterization of the lethal (1)discs large-1 Oncogene of Drosophila

布莱恩特博士建议继续他对果蝇致死的大1号椎间盘(L(1)d.lg-1)基因和癌基因的分析。该基因的突变会导致图像组织的肿瘤性转化，从而延长幼虫的寿命，并阻碍幼虫的羽化。其他等位基因允许正常的想象生长，但在变态过程中干扰分化。他对该基因座的初步遗传和分子特征表明，L(1)d.lg-1转录本至少存在三个互补基团和复杂的表达模式。对部分cDNA的测序表明，该基因座至少编码两种不同的多肽，其中一种似乎是跨膜的。数据库同源性搜索表明，预测的L(1)d.lg-1蛋白含有src同源区3或A-box。这个氨基酸基序在一些脊椎动物的致癌基因中被发现，并可以调节这些蛋白质的转化能力。布莱恩特博士计划分离L(1)d.lg-1转录本的全长cDNA，以确定整个蛋白质的序列。他还将使用这些cDNA来构建微型基因转换结构，以将遗传和分子结果关联起来。他将针对每一种预测的多肽制造抗体，用于定位和生化表征。最后，他将尝试通过对L(1)d.lg-1原有等位基因的这一区域进行测序，并通过使用体外突变在该区域产生特定的改变来分析A-box的功能。这些实验的结果应该会揭示L(1)d.lg-1癌基因的突变是如何导致肿瘤转化的，并应该有助于阐明该基因与脊椎动物癌基因的关系。%这项研究将提供有关果蝇发育过程中参与生长控制的基因调控的信息。该基因与哺乳动物参与转化为恶性生长的基因具有同源性。

Dr. Bryant proposes to continue his analysis of the lethal(1)discs large-1 (l(1)d.lg-1) locus, and oncogene of Drosophila melanogaster. Mutations in this locus cause neoplastic transformation of the imaginal tissue leading to an extended larval life and a block in pupariation. Other alleles allow normal imaginal growth but interfere with differentiation during metamorphosis. His initial genetic and molecular characterization of the locus has revealed the presence of at least three complementation groups and a complex pattern of expression of the l(1)d.lg-1 transcripts. Sequencing of partial cDNAs indicates that the locus encodes at least two different peptides, one of which appears to be transmembrane. Database homology searches have shown that the predicted l(1)d.lg-1 proteins contain the src homology region 3 or A-box. This amino acid motif has been found in several of the vertebrate oncogenes and can regulate the transforming ability of these proteins. Dr. Bryant plans to isolate full length cDNAs for the l(1)d.lg-1 transcripts to determine the sequence of the entire protein. He will also use these cDNAs to make minigene transformation constructs to correlate the genetic and molecular results. He will make antibodies to each of the predicted peptides to use for localization and biochemical characterization. Finally he will attempt to analyze the function of the A-box by sequencing this region from the pre-existing alleles of l(1)d.lg-1 and by creating specific alterations in this domain using in vitro mutagenesis. The results from these experiments should reveal how mutations in the l(1)d.lg-1 oncogene can cause neoplastic transformation and should help clarify the relationship of this gene to the vertebrate oncogenes. %%% This study will yield information about the regulation of a gene involved in growth control during development in Drosophila. This gene has homologies to mammalian genes involved in the transformation to malignant growth.