DETERMINANTS OF GLOMERULAR ORGANIZATION

肾小球组织的决定因素

• 批准号: 6344774
• 负责人: Charles A Greer
• 金额: $ 7.44万
• 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: 2000-08-01 至 2001-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6344774
• 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.

多条证据支持这样的观点，即来自表达相同气味受体（OR）的嗅觉受体神经元的轴突在很大程度上仅会聚到嗅球中的2个或几个肾小球上。为了实现这一点，在嗅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构成了一套独特的分子标签/决定因素，提供了一个令人兴奋的机会，进一步研究组织的肾小球及其在气味处理的作用。.此外，由于蛋白质跟踪技术的最新进展，有机会调查ORS在嗅觉受体神经元中的时空蛋白，以了解它们的细胞内分布是否与轴突指导中的决定性作用一致。提出了三个具体的目标：1）一个特定的基因，编码一个OR序列，唯一地定义所有的传入轴突投射到一个肾小球？使用Lac-Z构建体，将研究表达特异性ORS的轴突的突触组织。2)其顶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，这些二尖瓣细胞的胞体应该是连续的，这一假设尚未得到解决。绿色荧光蛋白构建体可用于鉴定会聚在特定肾小球上的传入轴突。已识别的肾小球将被荧光或光密度示踪剂感染，以绘制其树突支配已识别的肾小球的二尖瓣细胞的分布。3)OR蛋白的细胞内分布是什么？虽然支持ORS的多重作用的证据是令人信服的，但在细胞内隔室中发现OR蛋白并不明显。使用绿色荧光蛋白编码序列与OR编码序列的融合，OR蛋白产物的时空特征将被评估以解决我们知识中的这一重大空白。总的来说，这些研究将揭示新的光组织的初级嗅觉投射，肾小球在气味处理中的作用，从肾小球出现的高阶投影的地形，最后，可能支配OR蛋白的细胞内分布的机制。这些结果对于嗅觉丧失、嗅觉减退、卡尔曼综合征及相关轴突导向疾病的诊断具有重要意义。