Understanding and treating neurogenetic conditions related to the Kennedy pathway

遗传性痉挛性截瘫（HSP）是一大类使人衰弱的遗传性疾病，可导致下肢无力和僵硬（痉挛）。不幸的是，病情发展，导致患者经历越来越多的困难。在某些形式的热休克症中，症状局限于下肢，而其他患者可能会出现更广泛的医学问题（称为复杂热休克症）。在这个提议中，我们将研究两种复杂形式的HSP，即SPG81和SPG82。这些复杂的热休克蛋白是由编码脂质代谢肯尼迪途径酶的基因突变引起的。这种途径产生两种类型的磷脂，它们是必不可少的脂肪样分子，有助于产生细胞膜（将细胞与周围环境隔离的屏障，也在细胞内形成内部隔室）。我们还将研究第三种影响神经系统的疾病，与SPG81和SPG82具有相似的临床特征，称为NEDMIMS，它是由另一种编码肯尼迪通路酶的基因突变引起的。目前，我们对NEDMIMS和SPG81、82的病理机制缺乏了解，也没有有效的治疗方法。在本研究中，我们将利用斑马鱼对三种遗传条件（SPG81、SPG82和NEDMIMS）进行建模，以揭示疾病机制并测试新的潜在治疗策略。我们的初步工作表明，SPG82可以在斑马鱼中真实地建模，其头部大小缩小，运动缺陷，脂质变化与患者相似。我们的初步实验将对SPG81和NEDMIMS斑马鱼模型的物理特征进行分析，并结合脂质类型和丰度的测量。在随后的实验中，我们将使用各种先进方法对所有3种模型的神经系统进行详细分析，其中包括显微镜和对受影响的细胞类型、细胞成分和分子途径的广泛分析。这将使我们能够获得在疾病状态下发生的过程的详细分子描述，从而确定所涉及的病理机制。在项目的最后一部分，我们将尝试各种方法来挽救疾病的病理。这将包括基因方法，我们重新表达受影响基因的“正常”副本，以及化学方法，我们将用选定的药物或更大的药物库治疗斑马鱼。那些挽救病理的治疗方法可能会在进一步的测试中被利用，这些测试将会在这个奖项之后进行。重要的是，热休克蛋白本质上是进行性的，因此有一个治疗窗口，使患者的治疗成为可能。这项工作很重要，因为它将确定三种高度衰弱的遗传疾病的机制，并允许确定新的潜在治疗方法。它也将与其他类似类型的神经系统疾病相关，包括更普遍的热休克蛋白，以及其他类型的运动神经元疾病。

The hereditary spastic paraplegias (HSP)s are a large group of debilitating genetic disorders that lead to lower limb weakness and stiffness (spasticity). Unfortunately, the condition progresses, leading to patients experiencing increasing difficulties. In some forms of HSP, symptoms are confined to the lower limbs, while other patients may suffer a wider range of medical problems (referred to as complex HSP). In this proposal we will investigate two complex forms of HSP, known as SPG81 and SPG82. These complex HSPs are caused by mutations in genes that encode enzymes of the so-called Kennedy pathway of lipid metabolism. This pathway makes two types of phospholipids, which are essential fat-like molecules that help generate cell membranes (barriers that enclose the cell from the surrounding environment and also make internal compartments inside the cell). We will also study a third disease that affects the nervous system, with similar clinical features to SPG81 and SPG82, called NEDMIMS, which is caused by mutations in another gene encoding an enzyme in the Kennedy pathway.Currently, we lack understanding of the pathological mechanisms of NEDMIMS and SPG81 and 82, and there are no effective treatments. In this proposal, we will use zebrafish to model the three genetic conditions (SPG81, SPG82 and NEDMIMS) to reveal disease mechanisms and test new potential therapeutic strategies. Our preliminary work indicates that SPG82 can be modelled faithfully in zebrafish, with reduced head size and defective movement, and changes in lipids similar to those seen in patients. Our initial experiments will perform the analysis of the physical features of the SPG81 and NEDMIMS zebrafish models, which will be combined with measurements of lipid types and abundance. In subsequent experiments we will carry out a detailed analysis of the nervous system in all 3 models using a variety of advanced approaches, which includes microscopy and an extensive analysis of the cell types, cellular components, and molecular pathways that are affected. This will allow us to obtain a detailed molecular description of the processes that occur in the disease state, and hence identify the pathological mechanisms involved. In the final part of the project we will try various approaches to rescue the disease pathology. This will include genetic approaches where we re-express a 'normal' copy of the affected gene, and chemical ones, where we will treat the zebrafish with selected drugs or a larger library of drugs. Those treatments that rescue the pathology may then be exploited in further testing that would follow on from this award. Importantly, the HSPs are progressive in nature and hence there is a therapeutic window, making treatment of patients possible. This work is important because it will identify the mechanisms of three highly debilitating genetic conditions, and allow the identification of new potential treatments for them. It will also have relevance for other similar types of neurological conditions, including the HSPs more generally, as well other types of motor neurone disease.