Molecular characterization in human neurons of genes associated with severe obesity identified from consanguineous pedigrees.

肥胖是一个日益严重的公共卫生问题。虽然它无疑是由不断变化的环境驱动的，但在种群内体重变化的基础上存在很大的遗传成分。遗传学研究指出，大脑，特别是一个被称为下丘脑的区域，在调节食欲方面起着至关重要的作用。例如，下丘脑瘦素黑皮质素途径中的单个基因突变导致严重的早发性肥胖。目前，大约10%的严重人类肥胖症有明确的病因，大多数突变位于编码黑皮质素途径的基因内。因此，严重肥胖的遗传病因仍有待发现，其鉴定可以揭示新的途径和潜在的治疗靶点。然而，在近交群体中研究这种疾病增加了发现致病突变的机会。使用这种方法，我们已经确定了两个新基因ADCY 3和ROCK 1的突变，这两个基因与严重肥胖有关。在本研究中，我们将详细研究这两种基因。鉴于大脑在调节体重和食物摄入方面的作用，我们将描述这些基因在人类神经元中的特征。我们不仅需要了解这些基因在正常细胞中的功能，还需要了解它们表达的神经元群体功能丧失的后果。尽管小鼠模型在过去对克服人类下丘脑难以接近的困难有很大帮助，但我们认为研究相关区域的人类组织对于更全面地了解这些基因的作用至关重要。与剑桥脑库的现有合作，使我们能够获得新鲜和固定的人类捐赠大脑样本。获得这种珍贵的材料，再加上单细胞测序和绘图技术的最新发展，为我们提供了一个及时的机会来研究这些基因在人类下丘脑中的表达位置。此外，我们最近获得了生成、遗传操作和分化人类干细胞为下丘脑神经元的能力。这将使我们能够直接检查这些肥胖相关突变在相关人类细胞中的影响。使用高通量DNA测序方法，我们还将继续寻找其他新的肥胖候选者。我们目前的提议是英国两个卓越中心在肥胖遗传学研究方面的合作。来自伦敦帝国理工学院的弗罗里小组带来了大量来自高度血缘关系的巴基斯坦血统的严重肥胖儿童;来自剑桥大学MRC代谢疾病部门的科尔、奥拉西利和杨的小组带来了定制的功能专业知识和获得人类下丘脑样本的机会。我们的目标是发现新的食欲控制途径，并揭示新的潜在治疗靶点，以解决肥胖问题。

Obesity is a growing public health problem. While it has undoubtedly been driven by the changing environment, there is a large heritable component underlying the variation in body-weight within the population. Genetic studies point to the brain, in particular a region called the hypothalamus, as having a crucial role in modulating appetite. For example, mutations of single genes in the hypothalamic leptin melanocortin pathway leads to severe, early-onset obesity. Around 10% of severe human obesity currently has a clear identified cause, with the majority of mutations sitting within the genes encoding the melanocortin pathway. Thus, much of the genetic aetiology of severe obesity remains to be uncovered, identification of which could reveal novel pathways and potential therapeutic targets. However, studying the disease in inbred populations increases the chances of finding disease causing mutations. Using this approach, we have identified mutations in two new genes, ADCY3 and ROCK1, that are associated with severe obesity. In this proposal, we will study both these genes in detail. Given the role of the brain in the regulation of body-weight and food intake, we will characterize these genes in human neurons. We need to understand not only the function of these genes in normal cells but also the consequences of loss of function for the neuronal populations in which they are expressed. Although murine models have been hugely helpful in the past to overcome the difficulties of inaccessibility of the human hypothalamus, we believe studying human tissue from the relevant regions is essential to get a fuller understanding of the role of these genes. An existing collaboration with the Cambridge Brain Bank, allows us access to fresh and fixed human donor brain samples. The access to this precious material, coupled with recent developments in single cell sequencing and mapping technologies provides us with a timely opportunity to study where these genes are expressed in the human hypothalamus. Additionally, we have recently acquired the ability to generate, genetically manipulate and differentiate human stem-cells into hypothalamic neurons. This will allow us to directly examine the impact of these obesity associated mutations in the context of a relevant human cell. Using high-throughput DNA sequencing approaches, we will also continue our search for other new obesity candidates. Our current proposal is a collaborative venture between two UK centres of excellence in the study of the genetics of obesity. The group of Froguel, from Imperial College London, brings a large collection of severely obese children from highly consanguineous Pakistani pedigrees; and the group of Coll, O'Rahilly and Yeo, from the MRC Metabolic Diseases Unit at the University of Cambridge, who bring bespoke functional expertise and access to human hypothalamic samples. Our aim is to uncover novel appetite control pathways and reveal new potential therapeutic targets in order to tackle obesity.