MICA Cryo-chronobiology: how do cold-inducible chaperones maintain neural clock function under brain temperature fluctuation?

MICA 冷冻时间生物学：冷诱导伴侣如何在脑温度波动下维持神经时钟功能？

基本信息

批准号：
MC_EX_MR/S022023/1
负责人：
Nina Rzechorzek
金额：
$ 67.95万
依托单位：
MRC Laboratory of Molecular Biology
依托单位国家：
英国
项目类别：
Fellowship
财政年份：
2019
资助国家：
英国
起止时间：
2019 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=MC_EX_MR%2FS022023%2F1
关键词：
MICA Cryo chronobiology how do

项目摘要

Biological clocks are fundamental to life, adapting us to predictable changes in our environment. Disruption of these clocks occurs in several brain disorders including dementia - a leading cause of death in the UK. Understanding how clocks work means that we can control them; a fresh strategy to tackle some of our most complex global health challenges.At the molecular level, feedback loops support daily 'circadian' rhythms in cell function throughout the body. The 24-hour cycle of these rhythms is resistant to temperature variation, ensuring that cellular clocks do not speed up or slow down at different body temperatures. Remarkably however, cellular clocks synchronize to daily changes in body temperature, which means they must sense and respond to temperature shift. This 'temperature paradox' of the clockwork remains unexplained, especially for the brain where nerve cell activity produces rapid changes in brain temperature. What then keeps our brain cell clocks ticking robustly as brain temperature changes?Circadian rhythms and responses to cold are critical cellular functions that have been retained throughout evolution. Cold-inducible chaperones (CICs) are highly active proteins at cold temperatures; they safeguard the manufacture of key cellular proteins under conditions that would normally halt protein production. CICs do this by binding to messages transcribed from the DNA in each of our cells so that these messages can be translated into proteins that are critical for cell survival, including components of the clockwork. CIC activity also cycles in a circadian manner, responding to daily changes in body temperature. I propose that CIC-clock protein interactions are critical to timekeeping in brain cells. I will test whether these interactions are required to maintain brain cell clock function as brain temperature changes.Data from patients with brain injury show that, like body temperature, human brain temperature cycles with a 24-hour rhythm. However, brain and body temperature are not the same, and we need to know what happens in the healthy brain. In collaboration with Edinburgh Imaging, I will use a non-invasive MRI scan technique to map brain temperature in healthy volunteers at different times of the day. In parallel, I will monitor brain temperature cycles in mice remotely using radio transmitters. These experiments will establish normal human brain temperature ranges, and separate the effects of circadian and sleep-wake cycles on brain temperature rhythms.Experiments in Cambridge will then determine the impact of CIC versus clock protein disruption on brain cell circadian rhythms under simulated brain temperature cycles. The brain cell clock will be characterized 'in a dish' by tagging CIC and clock proteins with luminescent reporters in brain cells grown from human stem cells. This will make it possible to monitor the cyclic abundance of CIC and clock proteins in real time over several days at different temperatures, and during transitions between them. CIC and clock proteins will then be manipulated so that they are trapped in different parts of the cell and can no longer interact with each other. This 'trapping' will be entirely reversible such that CIC-clock interactions can be switched on or off during temperature shifts, to see what effect this has on clock function. Finally, radio transmitter experiments will be repeated in mice carrying genetic mutations in CIC and clock proteins. This work will establish a basis for modulating CIC-clock interactions in human cellular models of dementia and other chronic brain disorders. I predict that boosting CIC activity will protect and restore clock function in vulnerable brain cells. The results could ultimately lead to new treatments for a range of disorders in which circadian rhythms are disrupted, and also new ways to manage our 'circadian health' in the modern world.

生物钟是生命的基础，它使我们适应环境中可预测的变化。这些生物钟的紊乱会导致多种脑部疾病，包括痴呆症——这是英国的一个主要原因。了解时钟的工作原理意味着我们可以控制它们；解决一些最复杂的全球健康挑战的新策略。在分子水平上，反馈循环支持全身细胞功能的日常“昼夜节律”节律。这些节律的 24 小时周期不受温度变化的影响，确保细胞时钟在不同体温下不会加快或减慢。然而值得注意的是，细胞时钟与体温的日常变化同步，这意味着它们必须感知温度变化并做出反应。这种发条装置的“温度悖论”仍然无法解释，特别是对于神经细胞活动导致大脑温度快速变化的大脑而言。那么，当大脑温度发生变化时，是什么让我们的脑细胞时钟保持强劲运转呢？昼夜节律和对寒冷的反应是在整个进化过程中一直保留的关键细胞功能。冷诱导伴侣 (CIC) 是在低温下高度活跃的蛋白质；它们在通常会停止蛋白质生产的条件下保护关键细胞蛋白质的制造。 CIC 通过与每个细胞中 DNA 转录的信息结合来实现这一点，以便这些信息可以转化为对细胞生存至关重要的蛋白质，包括发条机构的成分。 CIC 活动也以昼夜节律方式循环，对体温的每日变化做出反应。我认为 CIC 与时钟蛋白的相互作用对于脑细胞的计时至关重要。我将测试当大脑温度发生变化时，这些相互作用是否是维持脑细胞时钟功能所必需的。脑损伤患者的数据表明，与体温一样，人类大脑温度也以 24 小时节律循环。然而，大脑和体温并不相同，我们需要知道健康的大脑会发生什么。我将与爱丁堡成像公司合作，使用非侵入性 MRI 扫描技术来绘制健康志愿者在一天中不同时间的大脑温度图。与此同时，我将使用无线电发射器远程监测小鼠的大脑温度周期。这些实验将建立正常的人类大脑温度范围，并区分昼夜节律和睡眠-觉醒周期对大脑温度节律的影响。剑桥的实验将确定在模拟大脑温度循环下，CIC 与时钟蛋白破坏对脑细胞昼夜节律的影响。脑细胞时钟将在“培养皿中”进行表征，方法是用人类干细胞生长的脑细胞中的发光报告基因标记 CIC 和时钟蛋白。这将使在不同温度下以及在它们之间的转换期间实时监测 CIC 和时钟蛋白的循环丰度成为可能。然后，CIC 和时钟蛋白将被操纵，使它们被困在细胞的不同部分，并且不能再相互作用。这种“捕获”将是完全可逆的，以便在温度变化期间可以打开或关闭 CIC 时钟相互作用，以了解这对时钟功能有何影响。最后，将在携带 CIC 和时钟蛋白基因突变的小鼠中重复无线电发射器实验。这项工作将为调节痴呆症和其他慢性脑部疾病的人类细胞模型中的 CIC 时钟相互作用奠定基础。我预测，增强 CIC 活动将保护和恢复脆弱脑细胞的时钟功能。研究结果最终可能会带来针对一系列昼夜节律被扰乱的疾病的新疗法，以及管理现代世界“昼夜节律健康”的新方法。