PROGRAMS OF GENE EXPRESSION IN OLFACTORY NEUROGENESIS

描述(申请人提供)：神经系统中神经元多样性的产生是一个复杂的过程，涉及到大量细胞谱系的指定和分化。连续的发育程序控制单个神经元类型的确定和增殖、细胞迁移、轴突延伸，最终控制功能性突触连接的形成。这些步骤中的大多数由特定的基因表达程序控制，例如导致神经元前体生成的细胞命运决定。然而，成熟神经元与其祖细胞分化的遗传程序在很大程度上仍不为人所知，部分原因是在其自然环境中研究神经元干细胞存在困难。 在脊椎动物嗅觉系统中，初级感觉神经元通过神经前体细胞的增殖和分化在整个成年生活中不断再生。这一特征使嗅觉系统特别适合于研究神经干细胞的特性。虽然这一谱系的某些阶段已被确定为一组有限的分子标记，但定义和调节嗅神经发生的遗传程序在很大程度上仍不清楚。这一生物学问题所固有的巨大复杂性要求对基因表达的全球观点，以便充分了解在这个发育系统中神经功能和发育的遗传网络。 在这项应用中，我们提出了一套基于DNA微阵列的技术来在全球范围内识别与嗅觉神经元谱系的不同阶段相对应的基因表达模式。我们建议(1)在胚胎发育和病变诱导的再生过程中对嗅觉上皮细胞的基因表达进行时间谱分析，以确定与这一谱系的不同阶段相关的基因和基因表达程序，包括最早的多能祖细胞阶段；以及(2)通过比较已知扰乱嗅神经发生的突变体的基因表达模式来完善这一分析，并通过RNA原位杂交验证基于微阵列的预测。 我们的方法有望提供关于嗅觉感觉神经元从其祖细胞中产生的分子和途径的非常详细的信息。此外，还将为嗅觉神经发生的不同阶段产生更广泛的分子标记。在全基因组水平上阐明这些遗传程序将为了解来自各种神经系统和非神经系统的前体干细胞的特性提供有价值的见解。

DESCRIPTION (provided by applicant): The generation of neuronal diversity in the nervous system is a complex process involving the specification and differentiation of a multitude of cellular lineages. Successive developmental programs control the determination and proliferation of individual neuronal types, cell migration, axon extension, and ultimately the formation of functional synaptic connections. Most of these steps are controlled by specific gene expression programs, such as cell fate decisions that lead to the generation of neuronal precursors. The genetic programs underlying the differentiation of mature neurons from their progenitors remain largely unknown, however, in part because of the difficulty in studying neuronal stem cells in their native environments. In the vertebrate olfactory system, primary sensory neurons are continuously regenerated throughout adult life via the proliferation and differentiation of neural progenitor cells. This feature makes the olfactory system particularly amenable for studies on the properties of neuronal stem cells. While some stages of this lineage have been identified with a limited set of molecular markers, the genetic programs that both define and regulate olfactory neurogenesis remain largely unknown. The enormous complexity inherent in this biological problem demands a global view of gene expression in order to fully understand the genetic networks underlying neural function and development in this developmental system. In this application we propose a suite of DNA microarray-based techniques to identify - on a global scale - patterns of gene expression corresponding to distinct stages of the olfactory neuron lineage. We propose (1) to perform temporal profiling of gene expression in olfactory epithelium during embryonic development and lesion-induced regeneration to identify the genes and gene expression programs associated with distinct stages of this lineage, including the earliest multipotent progenitor stage; and (2) to refine this analysis by comparing gene expression patterns in mutants known to disrupt olfactory neurogenesis, and to validate the microarray-based predictions by RNA in situ hybridizations. Our approach is expected to yield highly detailed information about the molecules and pathways responsible for the genesis of olfactory sensory neurons from their progenitor cells. In addition, a broader panel of molecular markers will be generated for distinct stages of olfactory neurogenesis. The elucidation of these, qenetic programs at the genome-wide level will provide valuable insights into the properties of progenitor stem cells from a variety of neural and non-neural systems.