Integrating functional genomics in primary human adipocytes to investigate gene regulatory circuitry for obesogenic cardiovascular traits

摘要 血脂异常，或称血脂异常，是心血管疾病(CVD)的危险因素，而心血管疾病是 全球范围内的死因。导致血清甘油三酯(TG)水平的遗传因素不是很好。 可以理解，尽管这一性状表现出约50%的遗传力。脂肪组织是人体重要的内分泌器官。 脂类动态平衡和脂肪细胞是通过游离脂肪调节的能量摄入和消耗的关键角色 酸吸收和甘油三酯的储存和动员。这个项目的目标是提高目前对 脂肪细胞基因表达和脂质处理途径的基因组调控机制。目标1是 旨在通过以下方法确定受局部基因控制的血清甘油三酯相关、脂肪表达基因 芬兰男性代谢综合征(METSIM)队列中数量性状基因座(cis-eQTL)的表达。我们 将在原代人类白色脂肪细胞(HWA)中使用启动子捕获Hi-C(pchi-C)来识别哪种脂肪 顺式eQTL与靶基因启动子相互作用，因为启动子相互作用的区域被丰富以进行调控 元素。我们的初步数据支持这一点，表明开放染色质中的SNPs与启动子相互作用 HWA中的区域对脂肪基因表达和血清甘油三酯水平的遗传力有显著影响 METSIM队列。通过进一步将脂质全基因组关联研究(GWAS)基因座整合到我们的分析中， 我们可以找到GWAs信号的靶基因和潜在机制。在目标2中，我们将执行RNA- 原发HWA中转座酶可及染色质(ATAC)-SEQ的测序、pCHI-C和检测 用饱和或单不饱和脂肪酸处理它们，以研究基因组的调节 对脂质挑战的反应机制发生了变化。这将有助于检测介导基因的元件 通过pchi-C和ATAC-seq检测基因表达的变化。我们假设基因组调控 该系统中发现的体系结构可以跨人群使用。因此，我们将使用我们的数据来检查 我们实验室发现墨西哥特有的区域与高血清TGS有关。一个轨迹打开 11号染色体包含一种高TGS和餐后TG水平升高的危险单倍型 吃饭。在HWA中发现的调节回路在脂质刺激前后都是非常有价值的。 以了解墨西哥特有的变异如何导致该基因座的遗传失调。目标2将 还可以使用英国生物库(UKBB)进行基因与环境的交互作用分析。许多系统代谢 肥胖和超重个体更有可能出现的紊乱涉及脂肪细胞的功能。 到目前为止，UKBB已经收集了大约15万人的基因型别和深层临床表型，并采取了措施 包括体重指数、血脂和其他心血管疾病危险因素。我们将使用BMI作为交互术语来测试 在原发HWA中，脂质挑战响应区内的变异更有可能影响TGS 这种常见的肥胖测量方法。目标1和目标2与NHLBI改善医疗保健的使命相一致 通过鉴定不同人群中性状相关变异的机制，研究心血管疾病与血脂异常的关系。

ABSTRACT Abnormal serum lipid levels, or dyslipidemias, are risk factors for cardiovascular disease (CVD), the leading cause of death worldwide. The genetic factors underlying serum triglyceride (TG) levels are not well understood, despite this trait exhibiting ~50% heritability. Adipose tissue is an important endocrine organ for lipid homeostasis, and adipocytes are key players in energy intake and expenditure mediated through free fatty acid uptake and TG storage and mobilization. The goal of this project is to improve the current understanding of genomic regulatory mechanisms in gene expression and lipid processing pathways in adipocytes. Aim 1 is targeted to identify serum TG-correlated, adipose-expressed genes that are under local genetic control by expression quantitative trait loci (cis-eQTLs) in the Finnish METabolic Syndrome In Men (METSIM) cohort. We will use promoter Capture Hi-C (pCHi-C) in primary human white adipocytes (HWA) to identify which adipose cis-eQTLs interact with the target gene promoter, as promoter-interacting regions are enriched for regulatory elements. Our preliminary data support this, showing that SNPs in open chromatin within promoter-interacting regions in HWA contribute significantly to the heritability of adipose gene expression and serum TG levels in the METSIM cohort. By further integrating lipid genome-wide association study (GWAS) loci into our analysis, we can find a target gene and underlying mechanism of the GWAS signal. In Aim 2 we will perform RNA- sequencing, pCHi-C, and Assay for Transposase-Accessible Chromatin (ATAC)-seq in primary HWA after treating them with saturated or monounsaturated fatty acids, to investigate the genomic regulatory mechanisms altered in response to lipid challenge. This will facilitate detection of elements mediating gene expression changes, assayed through both pCHi-C and ATAC-seq. We hypothesize that genomic regulatory architecture uncovered in this system can be used across populations. We will thus use our data to examine Mexican-specific regions found to be associated with high serum TGs in our laboratory. One locus on chromosome 11 contains a risk haplotype for both high TGs and increased post-prandial TG levels after a fatty meal. The regulatory circuitry, identified in HWA both before and after lipid challenge, can be highly valuable for understanding how Mexican-specific variation might lead to genetic dysregulation at this locus. Aim 2 will also use the UK Biobank (UKBB) for genotype-by-environment interaction analyses. Many systemic metabolic disturbances that are more likely to be present in obese and overweight individuals involve adipocyte function. The UKBB has so far collected genotypes and deep clinical phenotypes for ~150,000 humans, with measures including BMI, lipids, and other CVD risk factors. We will use BMI as an interaction term to test whether the variants within lipid challenge-responsive regions in primary HWA are more likely to affect TGs in the context of this common obesity measurement. Aims 1 and 2 align with the mission of NHLBI to improve medical care for CVD and dyslipidemia through identification of mechanisms of trait-associated variants in diverse populations.