Regulation of Neuron Development by a Nuclear Receptor

在神经系统发育过程中，神经元由胚胎前体细胞产生。随后，神经元彼此分化，产生无数的神经元细胞类型，每种细胞都具有不同的身份。例如，涉及嗅觉的神经元与那些调节呼吸的神经元非常不同。因此，神经元在生理学、神经递质表达、轴突形态和突触连接方面彼此不同。具体的神经元身份的机制还不清楚，但已知涉及“打开”和“关闭”其他基因的蛋白质的活性。 本研究的目的是通过研究线虫线虫的fax-1基因，增加对神经元身份特化过程的理解。fax-1编码一种核激素受体蛋白质，这种蛋白质开启和关闭其他基因。当fax-1基因突变时，一些神经元不能正常形成。线虫是一个很好的模型系统，在其中研究神经系统发育的机制，凭借其良好的特征302细胞神经系统和其几乎完全测序的基因组。在无脊椎动物神经系统发育中起作用的其他分子已被证明在脊椎动物中执行类似的功能。与fax-1相关的人核激素受体已被鉴定并显示在人感光细胞中特异性表达。因此，对C.秀丽线虫可能提供人类神经系统特异性基因的功能。本研究将通过鉴定一些受fax-1调控的基因来研究神经元身份特异性的分子机制。首先，将定义与FAX-1蛋白结合的DNA序列。第二，fax-1调控的基因将通过两种主要的实验方法进行鉴定。在一种方法中，在基于酵母的系统中鉴定与FAX-1蛋白结合的特异性DNA片段。在第二种方法中，使用最先进的DNA微阵列技术来识别响应fax-1而打开或关闭的基因。这项研究将推进我们对不同神经元细胞类型如何被指定的基本生物学问题的认识，并可能定义一种新的发育机制，这种机制从线虫到人类都是保守的。另一个主要目标是通过让学生在涉及“经典”重组DNA和当前基因组技术的分子遗传学研究项目中发挥主要作用来推进本科教育。

During nervous system development, neurons are generated from embryonic precursor cells. Subsequently, neurons diverge from each other to create myriad neuronal cell types, each with distinct identities. For example, neurons involved in smell are quite different from those that function in regulation of breathing. Thus neurons come to differ from each other in terms of physiology, neurotransmitter expression, axonal morphology, and synaptic connectivity. The mechanisms by which individual neuron identities are specified are not well understood, but are known to involve the activity of proteins that "turn on" and "off" other genes. The objective of this research is to increase understanding of the process of specification of neuron identity by studying the fax-1 gene of the nematode Caenorhabditis elegans. fax-1 encodes a nuclear hormone receptor protein, the type of protein that turns on and off other genes. When the fax-1 gene is mutated, some neurons don't form properly. The nematode is an excellent model system in which to study the mechanisms of nervous system development by virtue of its well-characterized 302-cell nervous system and its virtually completely-sequenced genome. Other molecules that function in invertebrate nervous system development have been shown to perform similar functions in vertebrates. A human nuclear hormone receptor related to fax-1 has been identified and shown to be expressed specifically in human photoreceptor cells. Therefore, a study of fax-1 in C. elegans may inform on the function of a human nervous system-specific gene. This study will investigate the molecular mechanism of specification of neuron identity by identifying some of the genes that are regulated by fax-1. First, the DNA sequence to which the FAX-1 protein binds will be defined. Second, the genes that are regulated by fax-1 will be identified through two major experimental approaches. In one approach specific DNA fragments to which the FAX-1 protein binds are identified in a yeast-based system. In a second approach, genes that are turned on or off in response to fax-1 are identified using state-of-the-art DNA microarray technology. This research will advance our knowledge about the basic biological question of how different neuronal cell types are specified and may define a new developmental mechanism that is conserved from nematodes to humans. An additional major goal is to advance undergraduate education by giving students primary roles in a molecular genetic research project that involves both "classical" recombinant DNA and current genomic technologies.