Regulation of mammalian odorant receptor gene expression

描述（由申请人提供）：用于神经元多样性的实验上易处理的系统是嗅觉系统，其利用1000个（OR）基因的库，每个基因在嗅觉感觉神经元（OSN）的子集中表达。给定的OSN表达来自一个等位基因的单个OR基因。OSN投射单个轴突，其支配嗅球中的特定肾小球，并且这种选择部分地由所表达的OR的特异性决定。因此，嗅觉系统功能的中心是OR基因表达的过程。然而，在OR基因发现12年后，OR表达的调控仍然是个谜;出版物少之又少，而且相互矛盾。 在初步研究中，已经开发了模型系统。短转基因赋予OR基因表达的许多复杂特征。这显示了两个OR基因（MOR 23和M71），它们彼此之间几乎没有序列同源性，并且位于不同的染色体上。MOR 23转基因表达需要395个碱基对区域。如果没有Lhx 2同源结构域蛋白，OSN不会在终末分化，并且M71不表达。 要测试的假设是，OR基因的表达（以及类似地，犁鼻受体基因的表达，另外两种类型的化学感受器基因）是由短启动子控制的，所述短启动子包含正常表达模式所必需的基序，并且可能被DNA重排改变。该方法是对小鼠的遗传操作：转基因和靶向诱变。 具体目标是：一曰：测试同源域基序在M0 R 23内源性基因表达中的功能，并确定Lhx 2缺陷是否可以通过M71表达来挽救。2.将短启动子的概念推广到其他气味受体基因。3：确定犁鼻受体基因的短转基因是否表达。4.寻找气味受体基因中的DNA重排。 试验数据、工具、试剂、技术、专门知识和人员在实验室中已得到很好的建立。由于哺乳动物的脑功能依赖于大量的神经元细胞类型，这项研究将有助于我们了解神经发育和功能。

DESCRIPTION (provided by applicant): An experimentally tractable system for neuronal diversity is the olfactory system, which utilizes a repertoire of 1000 (OR) genes each expressed in a subset of olfactory sensory neurons (OSNs). A given OSN expresses a single OR gene, from one allele. An OSN projects a single axon that innervates a specific glomerulus in the olfactory bulb, and this choice is determined in part by the specificity of the expressed OR. Thus, central to the function of the olfactory system is the process of OR gene expression. However, twelve years after the discovery of OR genes, regulation of OR expression remains enigmatic; publications are far and few between, and are contradictory. In preliminary studies, model systems have been developed. Short transgenes impart many of the intricate features of OR gene expression. This was shown for two OR genes (MOR23 and M71) that have little sequence homology to each other and are located on different chromosomes. A 395 basepair region is required for MOR23 transgene expression. Without the Lhx2 homeodomain protein, OSNs do not differentiate terminally and M71 is not expressed. The hypothesis to be tested is that OR gene expression (and similarly, expression of vomeronasal receptor genes, two other types of chemosensory receptor genes) is controlled by short promoters that contain motifs essential for normal patterns of expression, and that are possibly altered by DNA rearrangements. The approach is genetic manipulation of the mouse: transgenesis and targeted mutagenesis. The Specific Aims are: 1: To test the function of the homeodomain motif in expression of the MOR23 endogenous gene, and to determine if Lhx2 deficiency can be rescued by M71 expression. 2: To generalize the concept of short promoters to other odorant receptor genes. 3: To determine if short transgenes of vomeronasal receptor genes are expressed. 4: To search for DNA rearrangements in odorant receptor genes. Pilot data, tools, reagents, techniques, expertise and personnel are well established in the laboratory. As mammalian brain function relies on a great many neuronal cell types, this research will contribute to our understanding of neural development and function.