Molecular Mechanism of Photoperiodic Time Measurement

描述(由申请人提供)：季节性适应的失败可能会对生物体的生存和繁殖成功产生关键影响。在人类中，季节性情感障碍(SAD)就是一个例子。虽然SAD的发病机制仍不清楚，但其原因是光照条件的季节性变化。为了将有关季节变化的信息整合到它们的发育中，许多生物进化出了感知日长变化的机制。我们研究计划的长期目标是阐明日长测量的分子机制。虽然光周期调控的分子机制在许多生物中还没有得到很好的描述，但模式植物拟南芥的光周期开花研究的最新进展已经为它们提供了一些线索。在拟南芥中，光周期时间测量机制的核心是花激活因子Constans(CO)基因的昼夜调控转录，以及光调控CO蛋白的稳定性和活性。在这项建议中，我们打算通过遗传、生化和基因组方法重点研究FKF1 E3泛素连接酶的功能，从而进一步表征这些核心分子机制。从植物光周期学中获得的知识往往有助于在其他系统中的发现。因此，这项研究的发现不仅对于植物研究，而且对于更广泛地理解哺乳动物和其他系统中的光周期也是重要的。此外，这些发现甚至可能为理解SAD的机制提供一些概念性线索。此外，这种类型的转录调控很可能在所有真核生物中都是保守的，因此这些发现将有助于理解基本的转录调控机制。总而言之，阐明光周期开花机制不仅对于理解主要的植物繁殖机制非常重要，这种机制直接适用于提高作物产量(对人类健康，特别是在发展中国家来说是一个重要的贡献者)，而且对于理解在生物体中普遍存在的复杂的泛素化依赖的转录机制也是重要的。

DESCRIPTION (provided by applicant): The failure of seasonal adaptations can have a critical impact on an organism's survival and reproductive success. In people, one example of this is Seasonal Affective Disorder (SAD). Although the mechanisms of SAD remain elusive, its cause is seasonal variation in light conditions. In order to integrate information about seasonal change into their development, many organisms have evolved mechanisms to sense changes in day length. The long-term goal of our research program is to elucidate the molecular mechanisms of day- length measurement. Although the molecular mechanisms of photoperiodism have not yet been well described in many organisms, recent advances in the study of photoperiodic flowering in the model plant Arabidopsis have shed some light on them. In Arabidopsis, the core of photoperiodic time-measurement mechanisms is circadian regulated transcription of the floral activator CONSTANS (CO) gene, and light regulated CO protein stability and activity. In this proposal, we intend to further characterize these core molecular mechanisms by focusing on the functions of FKF1 E3 ubiquitin ligase through genetic, biochemical, and genomic approaches. The knowledge obtained in plant photoperiodism has often facilitated discoveries in other systems. Therefore, findings made in this proposal will be important not only for plant research, but also for broader understanding of photoperiodism in mammals and other systems. In addition, the findings may even provide some conceptional cues to understanding the mechanisms of SAD. Moreover, this type of transcriptional regulation is likely conserved in all eukaryotes, thus the findings will contribute to the understanding of a fundamental transcriptional regulation mechanism. In conclusion, elucidating the photoperiodic flowering mechanism is important not only for understanding a major plant reproduction mechanism, one that is directly applicable for an improvement of crop yield (an important contributor to human health, especially in developing countries) but also in understanding a sophisticated ubiquitination-dependent transcriptional mechanism that is universal among organisms.