Exploration of a melanoma antigen (MAGE)-E3 ubiquitin ligase circuit governing circadian rhythm

所有动物，包括人类，都经历一个24小时的活动周期，如进食和睡眠。这种昼夜节律主要由外部线索（阳光）驱动，但由一组高度调节的生理和细胞过程维持。在细胞内，选定的蛋白质在24小时循环中的特定时间点产生，变得活跃或失活。这些蛋白质是昼夜节律所必需的：没有它们，睡眠和其他行为的24小时振荡就会变得异常或缺失。该研究项目调查了关键昼夜节律蛋白的调节和失活过程，以及这种形式的调节如何有助于维持昼夜节律。 许多蛋白质通过添加小分子（泛素）而失活，所述小分子充当靶向这些蛋白质以进行失活和处置的标记。添加泛素分子的蛋白质（称为E3连接酶）与其他蛋白质（称为法师蛋白）合作完成泛素化过程。有400种E3连接酶和60种法师蛋白质，细胞利用这两种蛋白质的组合来准确识别要处理的蛋白质以及何时进行这一过程。我们以前的NSERC资助的研究表明，当MAGEL 2蛋白缺失时（在基因工程小鼠中），昼夜节律被打乱。我们现在将集中精力发现MAGEL 2如何与许多在昼夜节律中很重要的E3连接酶蛋白相互作用。我们将测试MAGEL 2是否影响E3连接酶将泛素添加到关键昼夜节律蛋白的能力，以及MAGEL 2是否调节昼夜节律蛋白的稳定性和功能。该计划将阐明24小时昼夜节律的分子基础，这是动物行为最基本的特性之一。

All animals, including humans, undergo a 24-hour cycle of activities such as eating and sleeping. This circadian rhythm is primarily driven by external cues (sunlight) but is maintained by a highly regulated set of physiological and cellular processes. Inside the cell, selected proteins are produced, become active, or are inactivated at specific time points in the 24-hour cycle. These proteins are required for circadian rhythm: without them, the 24-hour oscillation of sleeping and other behaviours becomes abnormal or absent. This research program investigates the process by which key circadian rhythm proteins are regulated and inactivated, and how this form of regulation contributes to the maintenance of circadian rhythm. Many proteins are inactivated through the addition of a small molecule (ubiquitin), which serves as a flag that targets these proteins for inactivation and disposal. The proteins that add the ubiquitin molecule (called E3 ligases) cooperate with other proteins (called MAGE proteins) to complete the ubiquitylation process. There are 400 E3 ligases and 60 MAGE proteins, and combinations of these two types of proteins are used by the cell to accurately recognize which proteins to target for disposal and when to go about this process. Our previous NSERC-funded research demonstrated that when the MAGEL2 protein is absent (in a genetically engineered mouse), circadian rhythm is disrupted. We will now focus on discovering how MAGEL2 interacts with the many E3 ligase proteins that are important in circadian rhythm. We will test whether MAGEL2 affects the ability of the E3 ligases to add ubiquitin to key circadian rhythm proteins, and whether MAGEL2 regulates the stability and function of circadian rhythm proteins. This program will shed light on the molecular basis of the 24-hour circadian rhythm that is one of the most fundamental properties of animal behavior.