Seasonal Adaptation of a Circadian Clock

昼夜节律钟的季节适应

• 批准号: 8288134
• 负责人: ISAAC EDERY
• 金额: $ 33.23万
• 依托单位: RUTGERS, THE STATE UNIV OF N.J.
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-07-15 至 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8288134
• 关键词: 3' Splice Site; 3' Untranslated Regions; Alternative Splicing; Animals; Arousal; Behavior; Binding Sites; Biochemical; Biological Models; Brain; Calibration; Cell Culture System; Cell Culture Techniques; Cells; Circadian Rhythms; Climate; Comparative Study; Complex; Desiccation; Drosophila genus; Ensure; Environment; Event; Exhibits; Foundations; Gene Expression; Gene Expression Profile; Genetic Polymorphism; Goals; Heating; High temperature of physical object; Hour; Human; Introns; Life; Ligand Binding Domain; Light; Link; Maps; Mediating; Messenger RNA; Molecular; Natural Selections; Neurons; Nuclear; Organism; Pacemakers; Pattern; Phenotype; Phosphatidylinositols; Phospholipase C; Play; Population; Progress Reports; Proteins; RNA; RNA Sequences; RNA Splicing; Reading; Regulation; Relative (related person); Risk; Role; Signal Pathway; Signal Transduction; Site; Sleep; Sleep Wake Cycle; System; Technology; Temperature; Testing; Time; Trans-Activators; Variant; Work; base; circadian pacemaker; cis acting element; cold temperature; fly; genetic manipulation; genome-wide; in vivo; insight; loss of function; mRNA Precursor; mutant; neural circuit; novel; phospholipase C beta; preference; programs; public health relevance; response; tissue culture

DESCRIPTION (provided by applicant): In this proposal we will use Drosophila as a model system to understand how circadian (E24 hr) systems adapt to seasonal changes in environmental conditions, with an emphasis on the relatively uncharacterized role of temperature. A major foundation is based on our long-standing work showing that in D. melanogaster the temperature-dependent splicing of the 3'-terminal intron (called dmpi8) from the critical clock component period (per) is a prominent "thermosensor" that adjusts the distribution of daily wake-sleep cycles, eliciting seasonably appropriate responses. For example, on warm days splicing of the dmpi8 intron is inefficient leading to decreases in per RNA levels, events that prolong midday siesta and likely minimize the risks associated with desiccation during the hot midday hours. Recent progress indicates that multiple suboptimal splicing signals [i.e., 5' and 3' splice sites (ss)] are the basis for the thermosensitivity in the splicing efficiency of dmpi8, and endow D. melanogaster with the ability to prolong its midday siesta into the mid-to-late afternoon, presumably facilitating its adaptation to temperate climates where warm days are typically associated with extended periods of heat. Indeed, temperature-dependent changes in per 3'-terminal splicing efficiency and adjustments in daily wake-activity profiles are absent in several species of Drosophila that are naturally restricted to Afro- equatorial localities, wherein temperature and daylength undergo little fluctuation throughout the year. Consistent with our hypothesis, these non-thermal responsive species have strong 5' and 3'ss on their per 3'- terminal introns. Low temperatures likely stabilize the interaction of splicing factors with suboptimal splicing signals, providing a basis for thermal calibration. We will undertake a multi-faceted experimental strategy that includes biochemical, molecular, cell-culture and whole animal approaches to understand the cis- and trans- acting factors regulating the splicing efficiency of per 3'- terminal introns and how they modulate wake-sleep profiles in Drosophila. Newly identified natural polymorphisms in per that differentially regulate dmpi8 splicing and might vary geographically will be characterized. We will also determine whether the effects of dmpi8 splicing are preferentially mediated from the per-expressing morning or evening brain pacemaker centers and/or the more recently described arousal/sleep neurons. This analysis should provide further insights into our recent discovery that dmpi8 splicing regulates daytime sleep, suggesting novel non-circadian roles for per in modulating wake-sleep states. By undertaking comparative studies using a wide variety of natural populations and Drosophila species, this proposal offers a unique opportunity to integrate studies on gene expression and neural circuits controlling complex behaviors with ecological and evolutionary implications. On a broader perspective, our work suggests that natural selection operating at the level of splicing signals plays an important role in the thermal adaptation of life forms, raising broad implications for alternative splicing programs and transcriptome regulation, issues we will explore using massive-RNA sequencing technology. PUBLIC HEALTH RELEVANCE: Like all animals, human's exhibit daily wake-sleep cycles that are controlled by a network of specialized cells called circadian clocks. The circadian system is not only involved in daily timing but also eliciting seasonably appropriate responses. This proposal will investigate how circadian clocks respond to seasonal changes in temperature, critical for the adaptation of life forms to temperate climates.

描述（由申请人提供）：在本提案中，我们将使用果蝇作为模型系统，以了解昼夜节律（E24 hr）系统如何适应环境条件的季节性变化，重点是温度的相对未表征的作用。一个主要的基础是基于我们长期的工作表明，在D。黑腹果蝇3 ′-末端内含子（称为DMPI 8）从关键时钟成分周期（PER）的温度依赖性剪接是一种显著的“温度传感器”，其调节每日清醒-睡眠周期的分布，引起季节性的适当反应。例如，在温暖的日子里，dmpi 8内含子的剪接是低效的，导致每RNA水平的降低，延长中午午睡的事件，并可能最大限度地减少与炎热的中午时间期间干燥相关的风险。最近的进展表明，多个次优剪接信号[即，5'和3'剪接位点（ss）]是dmpi 8剪接效率热敏性的基础，并赋予D.黑腹果蝇具有将中午午睡延长到下午中后期的能力，这可能有助于其适应温带气候，在温带气候中，温暖的日子通常与长时间的炎热有关。事实上，在自然地局限于非洲赤道地区的几种果蝇中，每3 '末端剪接效率的温度依赖性变化和每日唤醒活动曲线的调整是不存在的，其中温度和日照长度全年几乎没有波动。与我们的假设一致，这些非热响应物种在其每3 '-末端内含子上具有强5'和3 'ss。低温可能稳定剪接因子与次优剪接信号的相互作用，为热校准提供基础。我们将采取多方面的实验策略，包括生物化学，分子，细胞培养和整个动物的方法来了解顺式和反式作用因子调节每3 '-末端内含子的剪接效率，以及它们如何调节果蝇的觉醒-睡眠模式。新发现的天然多态性per差异调节dmpi 8剪接和可能不同的地理特征。我们还将确定dmpi 8剪接的影响是否优先从预表达的早晨或晚上大脑起搏中心和/或最近描述的觉醒/睡眠神经元介导。这项分析应该为我们最近发现的dmpi 8剪接调节白天睡眠提供进一步的见解，这表明per在调节觉醒-睡眠状态中的新的非昼夜节律作用。通过使用各种自然种群和果蝇物种进行比较研究，该提案提供了一个独特的机会，将基因表达和控制复杂行为的神经回路的研究与生态和进化的影响相结合。从更广泛的角度来看，我们的工作表明，自然选择在剪接信号的水平上发挥着重要作用，在生命形式的热适应，提高了广泛的影响，选择性剪接程序和转录组调控，我们将探讨问题，使用RNA测序技术。 公共卫生相关性：像所有动物一样，人类每天都有清醒-睡眠周期，这是由一个称为生物钟的专门细胞网络控制的。昼夜节律系统不仅涉及日常时间，而且还引起季节性的适当反应。这项提案将调查生物钟如何对温度的季节性变化做出反应，这对生命形式适应温带气候至关重要。