The olfactory stimulation-dependent birth of neurons that express specific odorant receptors

项目摘要/摘要 嗅觉上皮是哺乳动物神经系统中三个主要区域之一，在那里有新的神经元 在一生中不断增加。在人类中，未能维持嗅觉感觉神经发生与嗅觉有关。 功能障碍，据估计，在美国有12.4%的成年人患有这种疾病，并可能对健康和质量产生不利影响 生活的一部分。治疗嗅觉功能障碍的一个关键障碍是我们对持续嗅觉的不完全理解 感觉神经发生受到调节和维持。一个相关的缺陷在于我们对为什么神经发生 持续存在于嗅觉上皮内。终生的嗅觉感觉神经发生被推定仅起作用于 替换受损的嗅觉感觉神经元。然而，我们实验室的工作表明，出生率 表达一部分气味受体的神经元在特定气味的刺激下加速，导致 这一建议的中心假设是：嗅觉上皮内持续的神经发生在一定程度上服务于 自适应功能。我们的结果不能很容易地用目前的嗅觉感觉神经发生模型来解释， 预测表达数百个不同受体基因的神经元的相对出生率 基因组是由一个过程随机确定的，在这个过程中，每个有丝分裂后的神经前体随机地“选择” 单个气味受体基因的表达。相应地，不同嗅觉感觉神经元的相对出生率 “亚型”应该不受嗅觉经验的影响。这项提案的总体目标是确定 气味刺激如何选择性地加速特定嗅觉感觉神经元亚型的出生率。我们的工作 模型是，当受到潜在显著气味的刺激时，部分亚型具有特殊的能力 通过选择性地促进具有相同血统的有丝分裂神经前体细胞的增殖来放大自身 并倾向于同样的亚型命运。这一模式将通过三个具体目标进行测试。AIM 1将测试 有一种假设认为，选择性地促进特定神经元亚型神经发生的嗅觉刺激是离散的， 有选择性地刺激这些亚型的显著气味。这将通过选择性的单细胞鉴定来进行测试 基于测序的方法，神经元亚型的范围，其出生率被性别特有的气味加速。目标 2将检验这一假设，即某些有丝分裂神经前体细胞倾向于特定的气味受体命运 它可以通过细胞增殖选择性地放大。这将通过绘制个体的亚型命运图来进行测试 使用遗传条形码和原位测序策略的祖细胞。目标3将检验成熟嗅觉-- 保守党特定亚型的感觉神经元具有促进神经前体细胞增殖的特殊能力。 通过气味刺激依赖的信号传递相同的血统。这将通过对基因的功能分析来测试 已发现在经历刺激依赖性神经发生的神经元亚型中有选择性地表达。这个 拟议中的实验有望阐明持续嗅觉感觉神经发生的关键方面，包括 它是如何被监管的，为什么会发生，以及它可能如何被操纵来增进人类健康。

Project Summary/Abstract The olfactory epithelium is one of three major regions within the mammalian nervous system where new neurons are added throughout life. In humans, a failure to maintain olfactory sensory neurogenesis is associated with olfactory dysfunction, which afflicts an estimated 12.4 percent of adults in the U.S. and can adversely affect health and quality of life. A key barrier to treating olfactory dysfunction is our incomplete understanding of how persistent olfactory sensory neurogenesis is regulated and maintained. A related deficiency lies in our understanding of why neurogenesis persists within the olfactory epithelium. Life-long olfactory sensory neurogenesis is presumed to function solely to replace damaged olfactory sensory neurons. However, work from our laboratory has demonstrated that the birthrates of neurons that express a fraction of odorant receptors are accelerated upon stimulation by specific odors, leading to the central hypothesis of this proposal: that persistent neurogenesis within the olfactory epithelium serves, in part, an adaptive function. Our results are not readily explained by the current model of olfactory sensory neurogenesis, which predicts that the relative birthrates of neurons expressing each of the hundreds of different receptor genes encoded in the genome are determined stochastically by a process in which each post-mitotic neural precursor randomly ‘chooses’ a single odorant receptor gene for expression. Accordingly, the relative birthrates of distinct olfactory sensory neuron ‘subtypes’ are expected to be impervious to olfactory experience. The overall objective of this proposal is to determine how odor stimulation selectively accelerates the birthrates of specific olfactory sensory neuron subtypes. Our working model is that a fraction of subtypes have a special capacity, upon stimulation by odors with potential salience, to amplify themselves by selectively promoting the proliferation of mitotic neural progenitors that are of the same lineage and predisposed toward the same subtype fate. This model will be tested through three specific aims. Aim 1 will test the hypothesis that olfactory stimuli that selectively promote the neurogenesis of specific neuron subtypes are discrete, salient odors that selectively stimulate those subtypes. This will be tested by identifying, via a selective single-cell sequencing-based approach, the scope of neuron subtypes whose birthrates are accelerated by sex-specific odors. Aim 2 will test the hypothesis that some mitotic neural progenitors are predisposed toward specific odorant receptor fates that can be selectively amplified via cell proliferation. This will be tested by mapping the subtype fates of individual progenitors using genetic barcoding and in situ sequencing strategies. Aim 3 will test the hypothesis that mature olfac- tory sensory neurons of specific subtypes have a special capacity to promote the proliferation of progenitors within the same lineage via odor stimulation-dependent signaling. This will be tested through functional analyses of genes that have been found to be selectively expressed by neuron subtypes that undergo stimulation-dependent neurogenesis. The proposed experiments are expected to elucidate key aspects of persistent olfactory sensory neurogenesis, including how it is regulated, why it occurs, and how it may be manipulated to enhance human health.