High-throughput in vivo profiling of candidate human obesity genes in zebrafish

保持健康的体重是降低疾病风险的关键。肥胖——体重增加到不健康的水平——与包括心血管疾病、糖尿病和癌症在内的一系列疾病密切相关。此外，肥胖给医疗保健系统带来了巨大负担。仅在英国，治疗与肥胖相关的疾病每年就花费NHS约50亿英镑，而更广泛的社会成本估计为每年约270亿英镑。因此，了解导致肥胖的机制对公共卫生具有重要意义。临床测序研究，如肥胖遗传学研究（GOOS; goos.org.uk）已经确定了数百个与儿童和成人严重肥胖相关的基因。现在至关重要的是了解哪些基因在功能被破坏时导致肥胖。这些知识将极大地提高我们的治疗目标分子的能力，以预防和改善肥胖。然而，确定哪些基因导致肥胖，而不是仅仅与肥胖有关，需要在实验室进行大量的功能实验。此外，目前测试基因如何导致肥胖的策略是不完善的，并且依赖于培养皿中的细胞培养，或者使用啮齿动物进行昂贵且耗时的方法。在这个提议中，我们将使用斑马鱼——一种小型淡水鱼——来测试基因是否会导致肥胖。使用斑马鱼的优点是：(1)在活体动物中测试基因功能，因此基因作用将在内源性生理相关背景下进行评估；(2)许多基因可以以廉价和快速的方式进行测试，提供关于候选人类肥胖基因的广泛信息；(3)每个基因的功能可以使用高分辨率成像技术在活体动物中无侵入性地可视化。特别是，该项目将重点关注候选人类肥胖基因如何影响大脑内神经元的功能，以调节食欲，摄食行为和对肥胖的易感性。我们的初步结果已经确定，信号蛋白3信号可以改变喂养神经元的发育，从而对肥胖产生后续影响。本提案的主要目标是：(i)了解Semaphorin 3信号传导如何影响进食神经元的实时活动动态，以及（ii）确定Semaphorin 3信号传导途径组分中的哪些遗传变异影响肥胖。总之，这个项目的结果将确定人类新的候选肥胖基因，并提供关于候选肥胖基因如何影响进食神经元的实时活动的新信息。这些结果将有助于促进新型抗肥胖疗法的发展。

Maintaining a healthy body weight is key to reducing disease risk. Obesity - an increase in body weight to an unhealthy level - is strongly associated with a range of diseases including cardiovascular disease, diabetes and cancer. Further, obesity places a huge burden on healthcare systems. In the UK alone, treating obesity-related medical conditions costs the NHS ~£5 billion/year with wider societal costs estimated at ~£27 billion/year. Therefore, understanding mechanisms that cause obesity is of primary public health importance. Clinical sequencing studies, such as the Genetics of Obesity Study (GOOS; goos.org.uk) have identified hundreds of genes that are associated with severe obesity in both children and adults. It is now vital to understand which genes, when their functions are disrupted, cause obesity. Such knowledge will greatly improve our ability to therapeutically target molecules to prevent and ameliorate obesity. However, identifying which genes cause obesity, as opposed to being only associated with obesity, requires extensive functional experimentation in the laboratory. Moreover, current strategies to test how genes cause obesity are imperfect and rely on culture of cells in petri dishes, or expensive and time-laborious methods using rodents. In this proposal, we will use zebrafish - a small freshwater fish - to test whether genes cause obesity. The advantages of using zebrafish are that (i) gene function is tested in living animals, and therefore gene roles will be assessed within an endogenous, physiologically-relevant context, (ii) many genes can be tested in an inexpensive and rapid fashion, providing extensive information on candidate human obesity genes, and (iii) the function of each gene can be visualized non-invasively in live animals using high-resolution imaging techniques. In particular, this project will focus on how candidate human obesity genes influence the function of neurons within the brain to regulate appetite, feeding behaviour and susceptibility to obesity. Our initial results have identified that Semaphorin 3 signalling modifies the development of feeding neurons, with subsequent effects on obesity. Primary objectives of this proposal are to (i) understand how Semaphorin 3 signalling influences the real-time activity dynamics of feeding neurons, and (ii) to identify which genetic variants in components of the Semaphorin 3 signalling pathway influence obesity. Altogether, the results from this project will identify new candidate obesity genes in humans and provide novel information on how candidate obesity genes influence the real-time activity of feeding neurons. These results will help stimulate the development of novel anti-obesity therapies.