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

所有的动物，包括人类，都会经历一个24小时的活动周期，比如吃饭和睡觉。这种昼夜节律主要由外部信号(阳光)驱动，但由一套高度调控的生理和细胞过程维持。在细胞内，选定的蛋白质在24小时周期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消失。这项研究计划调查关键的昼夜节律蛋白被调节和失活的过程，以及这种调节形式如何有助于维持昼夜节律。**许多蛋白质是通过添加一个小分子(泛素)来灭活的，泛素是针对这些蛋白质进行灭活和处理的标志。添加泛素分子的蛋白质(称为E3连接酶)与其他蛋白质(称为MAGE蛋白)合作，完成泛素化过程。有400个E3连接酶和60个MAGE蛋白质，这两种蛋白质的组合被细胞用来准确地识别哪些蛋白质是处理的目标，以及何时开始这一过程。我们之前由NSERC资助的研究表明，当MAGEL2蛋白缺失时(在基因工程小鼠中)，昼夜节律被打乱。我们现在将专注于发现MAGEL2如何与许多在昼夜节律中起重要作用的E3连接酶蛋白相互作用。我们将测试MAGEL2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MAGEL2是否调节昼夜节律蛋白的稳定性和功能。这个节目将阐明24小时昼夜节律的分子基础，这是动物行为的最基本特性之一。

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.