Molecular Mechanism of Photoperiodic Time Measurement

描述（由申请人提供）：季节性适应的失败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。尽管SAD的机制尚不清楚，但其原因是光照条件的季节性变化。为了将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白昼长度变化的机制。我们研究计划的长期目标是阐明日长测量的分子机制。虽然在许多生物中光周期现象的分子机制尚未被很好地描述，但模式植物拟南芥的光周期开花研究的最新进展已经为其提供了一些线索。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）基因的昼夜调节转录，以及光调节CO蛋白的稳定性和活性。在本研究中，我们打算通过遗传学、生物化学和基因组学的方法进一步研究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。在植物光周期中获得的知识往往促进了在其他系统中的发现。因此，本研究的发现不仅对植物研究具有重要意义，而且对更广泛地了解哺乳动物和其他系统的光周期现象也具有重要意义。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可能在所有真核生物中都是保守的，因此这一发现将有助于理解基本的转录调控机制。总之，阐明光周期开花机制不仅对理解主要的植物繁殖机制很重要，这一机制直接适用于提高作物产量（对人类健康的重要贡献，特别是在发展中国家），而且对理解生物体普遍存在的复杂的泛素化依赖转录机制也很重要。

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.