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

钙是所有细胞中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具有额外的作用。因此，肌肉细胞(肌细胞)进化出独特的结构和途径来调节体内的钙水平。人们对这些系统的正常功能以及它们如何在疾病中失灵的细节还没有完全了解。骨骼肌钙调节失调最戏剧性的例子之一是对全身麻醉剂(GA)的潜在致命反应，称为恶性高热(MH)。具有MH遗传风险的人显然是健康的，直到暴露在强烈的麻醉气体中，这会导致热量产生的迅速进展和危及生命的(恶性)增加(高热)。MH反应是由于钙调节失调引起的肌肉过度活动。即使在没有麻醉剂的情况下，MH的这些基因变化也可能导致持续的钙调节失调。这会导致肌细胞内的长期适应，导致肌肉疼痛和损伤，特别是当暴露在压力下，如运动和他汀类药物。运动还会导致过多的热量产生和中暑，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2000人中有1人)，也可以帮助有这些其他疾病过程的患者。对MH的研究为正常骨骼肌功能的机制提供了重要的发现，并揭示了这种钙失衡如何在包括心脏和大脑在内的其他组织中引起问题。以前研究的一个问题是缺乏正确的样本来适当地了解人类的机制。我很幸运能够在英国唯一一个MH单位进行这项研究，该单位有正在为MH进行调查的患者捐赠的人体组织样本。最近的研究表明，患有MH的人骨骼肌细胞中的钙水平高于没有MH的人。因此，这项研究将解决了解MH患者的遗传差异如何影响骨骼肌细胞钙进入和调节系统的基本需要。为了了解这些机制，我将研究MH患者和非MH患者钙离子进入心肌细胞的不同之处。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。我将使用的技术之一是高度专门化的，但它允许我直接测量心肌细胞中的钙含量。为了学习这项技术并将其引入英国，我将前往美国旅行六个月。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研究工具来尝试和确定钙失调的机制以及如何控制这种机制。在完成这些实验后，我的研究将检查突变的数量如何影响进入细胞并停留在细胞内的钙量。这是因为有一些MH家族，这种情况似乎是由多个基因相互作用的影响造成的。这提供了另一种将患者置于MH风险中的遗传机制。所获得的知识将使医生能够更好地认识到MH风险患者的基因变化可能如何影响患者暴露在GA中，从而允许患者接受更安全的GA。综上所述，通过确定参与短期和长期骨骼肌钙调节失调的结构以及它们如何相互作用，这项创新研究可以为新药开发寻找潜在的靶点。这些药物可用于预防和治疗MH和各种与钙调节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.