Identifying circadian rhythm genes from mouse mutants

描述(申请人提供)：在过去的十年里，我们在理解哺乳动物生物钟的分子机制方面取得了巨大的进步。昼夜节律振荡是由一组基因产生的，这些基因形成了转录自动调节反馈环路。在哺乳动物中，至少有七种不同的基因被认为是生物钟机制的“核心”昼夜节律元素。尽管取得了如此显著的进展，但很明显，仍有相当数量的调控哺乳动物昼夜节律的基因有待发现和鉴定。正向遗传筛选是发现昼夜节律基因最有效的工具，我们已经使用这种方法在西北大学功能基因组学中心的神经基因组学项目中筛选出昼夜节律突变的小鼠基因组。60多个新的昼夜节律突变被鉴定为大规模ENU突变筛选的一部分，以创造神经系统和行为表型的突变小鼠资源。我们的具体目标是：1.鉴定导致小鼠昼夜节律突变的基因。我们将测试‘加班’突变体代表一种新的昼夜节律基因的假设。2.确定我们大规模诱变筛选中分离到的20个最健壮的昼夜节律突变株的遗传图谱位置。为了给昼夜节律研究界提供一个更有价值的研究工具，我们建议定位20个新的昼夜节律突变。3.对一种新的夹带突变‘Swing-Shift’突变体进行鉴定。我们将克隆‘Swing-Shift’突变体，并测试‘Swing-Shift’小鼠在进入视交叉上核的光输入通路中存在分子或解剖损伤的假设。这些新的昼夜节律突变的特征和致病基因的鉴定应该会为哺乳动物昼夜节律的机制提供新的见解。

DESCRIPTION (provided by applicant): Over the past decade, tremendous progress has been made in our understanding of the molecular mechanism of circadian clocks in mammals. Circadian oscillations are generated by a set of genes that form a transcriptional autoregulatory feedback loop. In mammals, there are at least seven different genes that have been proposed as 'core' circadian elements of the clock mechanism. Despite this remarkable progress, it is clear that a significant number of genes that regulate circadian rhythms in mammals remain to be discovered and identified. Forward genetic screens have been the most effective tool for circadian gene discovery, and we have used this approach to screen the mouse genome for circadian rhythm mutants in the Neurogenomics Project in the Center for Functional Genomics at Northwestern University. Over 60 new circadian mutants were identified as part of a large-scale ENU mutagenesis screen to create a mutant mouse resource for nervous system and behavioral phenotypes. Our specific aims are: 1. To identify the gene responsible for the 'Overtime' circadian period mutant in mouse. We will test the hypothesis that the 'Overtime' mutant represents a novel circadian rhythm gene. 2. To determine the genetic map position of twenty of the most robust circadian mutants isolated in our large- scale mutagenesis screen. To provide a more valuable research tool for the circadian research community, we propose to map 20 new circadian mutants. 3. To characterize and identify the 'swing-shift' mutant which is a novel entrainment mutant in mice. We will clone the 'swing-shift' mutant and test the hypothesis that 'swing-shift' mice have either a molecular or an anatomical lesion in the photic input pathway into the suprachiasmatic nucleus. Characterization of these novel circadian mutants and the identification of the causative genes should provide new insight into the mechanism of the mammalian circadian clock.