Chitinase-related Growth Factors in Drosophila

彼得·布莱恩特 本论文将利用分子和遗传学方法研究果蝇中一个新发现的椎间盘生长因子家族的功能。这些因子是在来自胚盘培养物的条件培养基中发现的，并且已被证明与几丁质酶有关，而不是与先前已知的生长因子有关。它们与胰岛素协同作用，刺激体外培养的椎间盘细胞的增殖、极化和运动。第一个目标是通过分离和表征编码这些蛋白质的基因中的突变和缺陷来鉴定IDGF在体内的功能。将使用P元件诱变和辐射诱变来产生IDGF基因的功能缺失突变和缺陷，并将分析由单个和多个缺失产生的突变体表型。遗传方法也将用于确定个体IDGF是否可以补偿家族其他成员的损失，并测试这些蛋白质由脂肪体分泌到血液中的假设。第二个目标是测试每种IDGF和IDGF的组合（有和没有胰岛素）对细胞系和幼虫组织中的细胞增殖和极化的影响。每种IDGF将在杆状病毒表达系统中产生。将研究IDGF与细胞和蛋白质的结合，以确定这些蛋白质是否与细胞表面受体相互作用，并测试它们直接与胰岛素相互作用的可能性。还将测试IDGF的几丁质酶活性。第三个目标是检验IDGF基因的表达是在已知的转录因子serpent的控制下的假设，该转录因子serpent具有适当的表达模式和DNA结合特性。这些蛋白质的发现为果蝇的生长控制问题开辟了多种新途径。

Peter J. Bryant Molecular and genetic methods will be used to investigate the functions of a newly discovered family of Imaginal Disc Growth Factors (IDGFs) from Drosophila. The factors were discovered in conditioned medium from imaginal disc cultures, and have been shown to be related to chitinases rather than to previously known growth factors. They cooperate with insulin to stimulate the proliferation, polarization and motility of imaginal disc cells in vitro. The first goal is to identify the functions of IDGFs in vivo by isolating and characterizing mutations and deficiencies in the genes encoding these proteins. P-element mutagenesis and radiation mutagenesis will be used to produce loss-of-function mutations and deficiencies of the IDGF genes, and the mutant phenotypes produced by single and multiple losses will be analyzed. Genetic methods will also be used to determine whether individual IDGFs can compensate for loss of other members of the family, and to test the hypothesis that these proteins are secreted by the fat body into the blood. The second goal is to test the effects of each IDGF and of combinations of IDGFs, with and without insulin, on cell proliferation and polarization both in cell lines and in larval tissues. Each IDGF will be produced in a baculoviral expression system. The binding of IDGFs to cells and to proteins will be studied in order to determine whether these proteins interact with a cell-surface receptor, and the possibility that they interact directly with insulin will be tested. The IDGFs will also be tested for chitinase activity. The third goal is to test the hypothesis that the expression of IDGF genes is under the control of the known transcription factor serpent, which has an appropriate expression pattern and DNA-binding properties. The discovery of these proteins opens up a variety of new approaches to the problem of growth control in Drosophila.