Target Specificity in the Drosophila Olfactory System

果蝇嗅觉系统的目标特异性

• 批准号: 6710540
• 负责人: S. Lawrence Zipursky
• 金额: $ 27.11万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-12-08 至 2008-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6710540
• 关键词: Drosophilidae; cell adhesion molecules; chemoreceptors; developmental neurobiology; gene mutation; gene targeting; genetically modified animals; olfactions; olfactory nerve; protein isoforms; protein structure function; synapses

DESCRIPTION (provided by applicant): The olfactory system in Drosophila melanogaster provides a unique opportunity to explore the mechanisms by which neurons form connections during development. Olfactory receptor neurons (ORNs) that express the same odorant receptors connect to the same neurons in the antennal lobe, while neurons that express different odorant receptors connect to different neurons. The studies proposed here are directed towards understanding the molecular basis of this specificity. Genetic studies have revealed that different neurons use different constellations of cell surface proteins to control specificity including Dscam, N-cadherin, Lar receptor tyrosine phosphatase and the novel cadherin, Flamingo. Of particular interest is the requirement for Dscam. Dscam is alternatively spliced and comes in many different forms (approximately 38,000) that may contribute to recognition specificity. In this proposal, the role of different forms of Dscam in controlling the specificity of neuronal connections in the olfactory system will be tested. Three sets of experiments are proposed to critically assess the importance of alternative forms of Dscam in ORN targeting. First, a set of deletions has been isolated that remove many different forms of Dscam. The effect of these mutations on a set of three different ORNs will be assessed in these mutants. Additional mutants lacking other forms will be isolated and their affects on ORN targeting will be explored. Second, homologous recombination will be used to introduce a single extracellular domain containing form of Dscam into the endogenous Dscam locus. This will reduce diversity from approximately 38,000 to 2 forms. The phenotypes in three sets of olfactory neurons will be assessed. And finally, single forms of Dscam will be expressed under heterologous promoters in both wild type and mutant backgrounds. Dominant phenotypes induced by these forms will be assessed. Forms that do not induce dominant phenotypes will be assessed for the ability to rescue the complete loss of function Dscam mutations. A better understanding of how neuronal connections are formed during development will provide insight into the mechanisms that may be disrupted in various neurological and psychiatric diseases.

描述（由申请人提供）：果蝇中的嗅觉系统为探索神经元在发育过程中形成连接的机制提供了独特的机会。表达相同气味受体的嗅觉受体神经元（ORN）连接到触角叶中的相同神经元，而表达不同气味受体的神经元与不同的神经元连接。这里提出的研究是针对理解这种特异性的分子基础的。遗传研究表明，不同的神经元使用不同的细胞表面蛋白星座来控制特异性，包括DSCAM，N-钙粘着蛋白，LAR受体酪氨酸磷酸酶和新型钙粘蛋白Flamingo。特别有趣的是对DSCAM的要求。 DSCAM是剪接的，并且有许多不同的形式（约38,000）可能有助于识别特异性。在此提案中，将测试不同形式的DSCAM在控制嗅觉系统中神经元连接的特异性中的作用。提出了三组实验，以严格评估ORN靶向中DSCAM替代形式的重要性。首先，已经隔离了一组删除，以消除许多不同形式的DSCAM。这些突变对这些突变体中的三个不同ORN的影响。将隔离缺乏其他形式的其他突变体，并将探讨它们对ORN靶向的影响。其次，同源重组将用于将包含DSCAM形式的单个细胞外域引入内源性DSCAM基因座。这将减少大约38,000形式的多样性。将评估三组嗅觉神经元中的表型。最后，DSCAM的单一形式将在野生型和突变背景的异源启动子下表达。这些形式引起的主要表型将被评估。将评估不诱导主导表型的形式，以挽救功能DSCAM突变的完全丧失的能力。更好地理解在开发过程中如何形成神经元联系，将为可能在各种神经和精神病中破坏的机制提供洞察力。