Investigating the fundamental mechanisms underlying the phenotypic diversity observed in RYR1-associated Malignant Hyperthermia.

钙是所有细胞正常功能的关键调节器，但在骨骼肌中，它在允许肌肉收缩方面有额外的作用。因此，肌肉细胞（肌细胞）已经进化出独特的结构和途径来调节它们内部的钙水平。这些系统的正常功能尚不完全清楚，它们在疾病中如何失效的细节也不完全清楚。骨骼肌钙失调的一个最引人注目的例子是对全身麻醉（GA）的潜在致命反应，称为恶性热疗（MH）。具有MH遗传风险的人在暴露于强麻醉气体之前，表面上是健康的，然后导致迅速进展和危及生命的（恶性）发热增加（热疗）。MH反应是由于钙调节失调引起的肌肉过度活动。即使没有麻醉暴露，MH的这些遗传变化也会导致持续的钙失调。这会导致肌细胞内的长期适应，导致肌肉疼痛和损伤，尤其是在暴露于运动和他汀类药物等压力下时。运动还会导致热量产生过多，引发中暑，其中最严重的中暑可能是致命的。因此，对MH的研究对不同的人都有好处；它可以直接帮助有MH风险的患者（高达1 / 2000人），也可以帮助有这些其他疾病过程的患者。对MH的研究提供了关于正常骨骼肌功能机制的重要发现，并揭示了这种钙失调如何导致包括心脏和大脑在内的其他组织出现问题。先前研究的一个问题是缺乏正确样本的可用性，无法对人类的机制进行适当的理解。我很幸运能够在英国唯一的MH单位进行这项研究，该单位有接受MH调查的患者捐赠的人体组织样本。最近的研究表明，与没有MH的人相比，MH患者骨骼肌细胞中的钙水平更高。因此，本研究将解决理解MH患者的遗传差异如何影响骨骼肌细胞中钙的进入和调节系统的基本需求。为了理解这些机制，我将研究MH患者与非MH患者钙进入肌细胞的差异。最初的重点将是使用各种分子研究技术研究最常见和最严重的突变。我将使用的一种技术是高度专业化的，但可以让我直接测量肌细胞中的钙含量。为了学习和引进这项技术到英国，我将去美国旅行六个月。一旦我测量了不同心肌细胞样本中的钙水平，我就可以使用几种尖端的研究工具来尝试确定钙失调的机制以及如何控制它。在完成这些实验之后，我的研究将会检验突变的数量如何影响进入和停留在细胞中的钙的数量。这样做的原因是，在一些MH家族中，这种情况似乎是由多个基因相互作用造成的。这提供了一个额外的遗传机制，使患者处于MH风险中。所获得的知识将使医生更好地认识到MH风险患者的遗传变化如何可能影响患者暴露于GA，从而使患者接受更安全的GA。总而言之，通过识别短期和长期骨骼肌钙失调的结构以及它们之间的相互作用，这项创新研究可以发现新药开发的潜在靶点。这些可以用来预防和治疗MH和各种与钙失调相关的长期疾病。

Calcium is a crucial regulator of normal function within all cells but in skeletal muscle it has additional roles in allowing the muscle to contract. Therefore, muscle cells (myocytes) have evolved unique structures and pathways to regulate calcium levels within them. The normal functioning of these systems are incompletely understood, as is the detail of how they fail in disease. One of the most dramatic examples of skeletal muscle calcium dysregulation is a potentially lethal reaction to general anaesthetics (GA) called malignant hyperthermia (MH). People with a genetic risk for MH are apparently healthy until exposed to the strong anaesthetic gases which then results in a rapidly progressive and life-threatening (malignant) increase in heat generation (hyperthermia). The MH reaction is due to muscle over-activity from calcium dysregulation. These genetic changes in MH can lead to ongoing calcium dysregulation even without anaesthetic exposure. This then causes long-term adaptations within the myocytes, resulting in muscle pain and damage especially when exposed to stress such as exercise and statin medication. Exercise can also lead to excess heat production and the development of heat illness of which the most severe form known as heat stroke can be fatal. As a result, research into MH has benefits for various people; it can directly help patients at risk of MH (up to 1 in 2,000 people), but also patients with these other disease processes. The studies on MH have provided important discoveries on the mechanisms of normal skeletal muscle function, as well as revealed how such calcium dysregulation can cause problems in other tissues including the heart and brain. A problem with previous research has been the lack of availability of the correct samples to allow a suitable understanding of the mechanisms in humans. I am fortunate to be able to undertake this research in the only MH unit in the UK which has human tissue samples donated by patients undergoing investigations for MH.Recent studies have shown that calcium levels in skeletal myocytes are higher in people who have had MH compared to those who have not. Consequently, this research will address the fundamental need to understand how the genetic differences seen in patients with MH affect the entry and regulation systems of calcium in skeletal myocytes. To understand these mechanisms I will examine how calcium entry into myocytes from patients with MH differs to those without. The initial focus will be to study the most common and serious mutations using various molecular research techniques. One of the techniques I will use is highly specialised, but allows me to directly measure the amount of calcium in myocytes. To learn and import this technique to the UK, I will travel to America for six months. Once I have measured the calcium levels in the different myocyte samples, I can then use several cutting-edge research tools to try and identify the mechanisms of calcium dysregulation and how this can be controlled. After completing these sets of experiments, my research will then examine how the number of mutations affects the amount of calcium that enters and stays in cells. The reason for this is that there are some families with MH where the condition appears to result from the effects of more than one gene interacting with each other. This provides an additional genetic mechanism placing patients at risk of MH. The knowledge gained will allow doctors to better recognize how the genetic changes in patients at risk of MH are likely to affect the patient on exposure to GA, as a result allow patients to receive a safer GA.To summarise, by identifying the structures involved in short and long-term skeletal muscle calcium dysregulation and how they interact, this innovative research could detect potential targets for the development of new drugs. These could be used to prevent and treat MH and various long-term conditions associated with calcium dysregulation.