DETERMINANTS OF GLOMERULAR ORGANIZATION

肾小球组织的决定因素

• 批准号: 6323344
• 负责人: Charles A Greer
• 金额: $ 23.39万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-07-01 至 2001-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6323344
• 关键词: axon; brain mapping; chemoreceptors; gene expression; genetically modified animals; innervation; laboratory mouse; neuroanatomy; neuronal guidance; olfactions; olfactory lobe; receptor expression

Multiple lines of evidence support the notion that the axons from olfactory receptor neurons expressing the same odor receptor (OR) largely converge onto only 2 or a few glomeruli in the olfactory bulb. To accomplish this there is an extraordinary reorganization of axons that occurs between the olfactory epithelium and the olfactory bulb. The pathfinding exhibited by axons during reorganization as well as their targeting of specific glomeruli appears to be influenced, at least in part, by the unique OR expressed by any single olfactory receptor neuron. Thus, ORS constitute a unique set of molecular tags/determinants that provide an exciting opportunity to study further the organization of the glomerulus and its role in odor processing. . Moreover, because of recent advances in protein tracking technology, the opportunity is presented to investigate the spatio-temporal proteins of ORS in olfactory receptor neurons in order to understand if their intracellular distribution is consistent with a determinant role in axon guidance. Three specific aims are proposed: 1) Does one specific gene, coding an OR sequence, uniquely define all of the afferent axons projecting to one glomerulus? Using Lac-Z constructs, the synaptic organization of axons expressing specific ORS will be studied. 2) What is the distribution of mitral cells whose apical dendrites innervate a specific glomerulus? While some evidence suggests that the somata of these mitral cells should be contiguous, the hypothesis has not been addressed. Green Fluorescent Protein constructs can be employed to identify the afferent axons converging on specific glomeruli. Identified glomeruli will be infected with fluorescent or light-dense tracers to map the distribution of mitral cells whose dendrites are innervating the identified glomerulus. 3) What is the intracellular distribution of OR protein? While the evidence favoring multiple roles for ORS is compelling, it is not evident in which intracellular compartments OR protein is found. Using Green Fluorescent Protein coding sequence fusions with OR coding sequences, the spatio- temporal characteristics of OR protein products will be assessed to address this significant gap in our knowledge. Collectively, these studies will shed new light on the organization of primary olfactory projections, the role of the glomerulus in odor processing, the topography of higher order projections emerging from glomeruli and finally, the mechanisms that may govern the intracellular distribution of OR proteins. These results may be significant for people suffering from anosmia and hyposmia, Kalman's Syndrome and related diseases of axon guidance.

多种证据支持这一观点，即表达相同气味受体 (OR) 的嗅觉受体神经元的轴突大部分集中到嗅球中的 2 个或几个肾小球上。为了实现这一目标，嗅觉上皮和嗅球之间发生了轴突的非凡重组。轴突在重组过程中表现出的寻路以及它们对特定肾小球的靶向似乎至少部分地受到任何单个嗅觉受体神经元表达的独特 OR 的影响。因此，ORS 构成了一组独特的分子标签/决定因素，为进一步研究肾小球的组织及其在气味处理中的作用提供了令人兴奋的机会。 。此外，由于蛋白质追踪技术的最新进展，我们有机会研究嗅觉受体神经元中 ORS 的时空蛋白质，以了解它们的细胞内分布是否与轴突引导中的决定性作用一致。提出了三个具体目标：1）是否有一个编码 OR 序列的特定基因唯一地定义了投射到一个肾小球的所有传入轴突？使用 Lac-Z 构建体，将研究表达特定 ORS 的轴突的突触组织。 2）其顶端树突支配特定肾小球的二尖瓣细胞的分布是什么？虽然一些证据表明这些二尖瓣细胞的体细胞应该是连续的，但这一假设尚未得到解决。绿色荧光蛋白构建体可用于识别会聚在特定肾小球上的传入轴突。识别出的肾小球将被荧光或光密示踪剂感染，以绘制其树突支配识别出的肾小球的二尖瓣细胞的分布图。 3）OR蛋白的细胞内分布是怎样的？虽然支持 ORS 多种作用的证据令人信服，但在哪个细胞内区室中发现 OR 蛋白尚不清楚。使用绿色荧光蛋白编码序列与 OR 编码序列融合，将评估 OR 蛋白产物的时空特征，以解决我们知识中的这一重大差距。总的来说，这些研究将为初级嗅觉投射的组织、肾小球在气味处理中的作用、肾小球出现的高阶投射的拓扑结构以及最终可能控制 OR 蛋白细胞内分布的机制提供新的线索。这些结果对于患有嗅觉缺失和嗅觉减退、卡尔曼综合症和轴突引导相关疾病的人可能具有重要意义。