Integrated cellular, mouse and human research on a novel missense variant influencing adiposity in Samoans

项目总结 在这场竞争性的更新中，我们重点描述了一种由基因组鉴定的新型错义变体- 前一资助期间萨摩亚人肥胖相关特征的广谱关联分析(GWAS)。这 错义变异与体重指数(BMI)高度相关，其影响幅度比其他任何变量都大 已知的常见肥胖风险变量。含有这个错义变体的基因编码一个假定的转录 因子(Tf)最近被认为与果蝇的能量代谢有关，但仍然很弱 具有特征的，尤其是在高等生物体中。本申请中提供的初步数据表明， 野生型及其错义变异体在3T3L1脂肪细胞中的过度表达 促进脂肪生成，促进脂肪储存，提高细胞存活率。此外，过度表达错误的意思 VARIANT促进更大的脂肪储存并减少能量底物氧化，这表明它是一种 “节俭”的变体。鉴于肥胖对疾病的巨大贡献，迫切需要更多的研究 了解这种错义变异导致人类肥胖的机制。中环 这项建议的目的是确定转铁蛋白基因及其错义变体如何为能量贡献 动态平衡，并确定介导这些影响的转录途径。我们将实现这一目标 利用细胞、小鼠和人类的综合研究来了解分子、生理和临床 错义变体的关联性。将实现以下具体目标：目标1将确定和 表征介导转铁蛋白基因及其错义变体对能量的影响的基因网络 培养细胞的动态平衡和能量底物代谢，一系列与代谢相关的组织来自 老鼠和123个萨摩亚人的脂肪组织；Aim 2将描述错义变体对 利用变异体特异性的全身和组织特异性能量动态平衡和能量底物代谢 Knockin小鼠；Aim 3将更准确地描述错义变体对代谢和 影响能量动态平衡的行为特征在500名萨摩亚人中的子集将是 根据他们的基因选择。这些更深层次的表型将通过在萨摩亚的新实地工作进行测量，方法是 重新联系最初GWAS研究的参与者，在此期间，代谢和营养 将测试与目标1和目标2中使用的条件/曝光类似的条件/曝光；目标4将更全面地描述 使用包括测试选择性签名的综合统计方法的错义变体， 通过多变量分析测试多效性，执行路径分析，测试错义变量x 环境交互作用，重点关注饮食和体力活动，测试TF基因x基因交互作用 关注AIMS 1和AIMS 2中确定的基因，并测试与从 目标3.成功完成这些目标将促进对肥胖及其下游的理解 健康结果，以及确定新的药理干预目标。

PROJECT SUMMARY In this competitive renewal we focus on characterizing a novel missense variant that was identified by genome- wide association analysis (GWAS) of obesity-related traits in Samoans during the previous funding period. This missense variant is highly associated with body mass index (BMI) with an effect size greater than any other known common obesity risk variant. The gene harboring this missense variant encodes a putative transcription factor (TF) that has recently been implicated in energy metabolism in Drosophila but remains poorly characterized, particularly in higher organisms. Preliminary data presented in this application indicate that overexpression of both the wild-type human gene and its missense variant in 3T3L1 adipocytes enhances adipogenesis, promotes lipid storage, and improves cell survival. In addition, overexpression of the missense variant promotes even greater lipid storage and reduces energy substrate oxidation, suggesting that it is a “thrifty” variant. Given the enormous contribution of obesity to disease, additional studies are urgently needed to understand the mechanisms by which this missense variant contributes to obesity in humans. The Central Aim of this proposal is to determine how the TF gene and its missense variant contribute to energy homeostasis and to identify the transcriptional pathways mediating these effects. We will achieve this goal using integrated studies in cells, mice, and humans to understand the molecular, physiological, and clinical relevance of the missense variant. The following Specific Aims will be pursued: Aim 1 will identify and characterize the gene networks mediating the effects of the TF gene and its missense variant on energy homeostasis and energy substrate metabolism in cultured cells, a range of metabolically-relevant tissues from mice, and adipose tissue from 123 Samoans; Aim 2 will characterize the impact of the missense variant on whole body and tissue-specific energy homeostasis and energy substrate metabolism using variant-specific knockin mice; Aim 3 will more precisely characterize the impact of the missense variant on metabolic and behavioral traits that impact energy homeostasis in a subset of 500 Samoans GWAS participants who will be selected based on their genotype. These deeper phenotypes will be measured with new fieldwork in Samoa by re-contacting participants from the original GWAS study, during which metabolic and nutritional conditions/exposures analogous to those used in Aims 1 and 2 will be tested; Aim 4 will more fully characterize the missense variant using comprehensive statistical approaches including testing for selective signatures, testing for pleiotropy via multivariate analyses, performing pathway analyses, testing for missense variant x environment interactions with a focus on diet and physical activity, testing for TF gene x gene interactions focusing on genes identified in Aims 1 and 2, and testing for association with newly gathered phenotypes from Aim 3. Successful completion of these aims will promote the understanding of obesity and its downstream health outcomes as well as identify novel targets for pharmacological interventions.