Data_Sheet_1_Whole-Exome Sequencing and hiPSC Cardiomyocyte Models Identify MYRIP, TRAPPC11, and SLC27A6 of Potential Importance to Left Ventricular Hypertrophy in an African Ancestry Population.pdf

Background: Indices of left ventricular (LV) structure and geometry represent useful intermediate phenotypes related to LV hypertrophy (LVH), a predictor of cardiovascular (CV) disease (CVD) outcomes.
Methods and Results: We conducted an exome-wide association study of LV mass (LVM) adjusted to height2.7, LV internal diastolic dimension (LVIDD), and relative wall thickness (RWT) among 1,364 participants of African ancestry (AAs) in the Hypertension Genetic Epidemiology Network (HyperGEN). Both single-variant and gene-based sequence kernel association tests were performed to examine whether common and rare coding variants contribute to variation in echocardiographic traits in AAs. We then used a data-driven procedure to prioritize and select genes for functional validation using a human induced pluripotent stem cell cardiomyocyte (hiPSC-CM) model. Three genes [myosin VIIA and Rab interacting protein (MYRIP), trafficking protein particle complex 11 (TRAPPC11), and solute carrier family 27 member 6 (SLC27A6)] were prioritized based on statistical significance, variant functional annotations, gene expression in the hiPSC-CM model, and prior biological evidence and were subsequently knocked down in the hiPSC-CM model. Expression profiling of hypertrophic gene markers in the knockdowns suggested a decrease in hypertrophic expression profiles. MYRIP knockdowns showed a significant decrease in atrial natriuretic factor (NPPA) and brain natriuretic peptide (NPPB) expression. Knockdowns of the heart long chain fatty acid (FA) transporter SLC27A6 resulted in downregulated caveolin 3 (CAV3) expression, which has been linked to hypertrophic phenotypes in animal models. Finally, TRAPPC11 knockdown was linked to deficient calcium handling.
Conclusions: The three genes are biologically plausible candidates that provide new insight to hypertrophic pathways.

背景：左心室（left ventricular, LV）结构与几何形态指数是与左心室肥厚（left ventricular hypertrophy, LVH）相关的具有应用价值的中间表型，而左心室肥厚是心血管（cardiovascular, CV）疾病（cardiovascular disease, CVD）预后的预测因子。
方法与结果：本研究在高血压遗传流行病学网络（Hypertension Genetic Epidemiology Network, HyperGEN）的1364名非洲裔（African ancestry, AAs）参与者中，针对校正为身高^2.7的左心室质量（left ventricular mass, LVM）、左心室舒张末期内径（left ventricular internal diastolic dimension, LVIDD）以及相对室壁厚度（relative wall thickness, RWT）开展了全外显子组关联研究。本研究同时采用单变异与基于基因的序列内核关联测试，探究非洲裔人群中常见及罕见编码变异是否会导致超声心动图特征的变异。随后，本研究采用数据驱动流程，基于人类诱导多能干细胞心肌细胞（human induced pluripotent stem cell cardiomyocyte, hiPSC-CM）模型，对候选基因进行优先级排序并筛选出适宜开展功能验证的靶基因。最终基于统计学显著性、变异功能注释、hiPSC-CM模型中的基因表达情况以及既往生物学证据，筛选出三个优先靶基因：肌球蛋白VIIA与Rab相互作用蛋白（myosin VIIA and Rab interacting protein, MYRIP）、转运蛋白颗粒复合物11（trafficking protein particle complex 11, TRAPPC11）以及溶质载体家族27成员6（solute carrier family 27 member 6, SLC27A6），并在hiPSC-CM模型中对其进行基因敲低处理。对基因敲低细胞的肥厚标志物基因进行表达谱分析后发现，其肥厚相关表达特征显著下调。MYRIP敲低组的心房利钠因子（atrial natriuretic factor, NPPA）与脑利钠肽（brain natriuretic peptide, NPPB）表达水平显著降低。针对心脏长链脂肪酸（fatty acid, FA）转运蛋白SLC27A6的基因敲低实验可导致窖蛋白3（caveolin 3, CAV3）表达下调，而该蛋白已在动物模型中被证实与心肌肥厚表型相关。最后，TRAPPC11基因敲低与细胞钙处理功能缺陷显著相关。
结论：上述三个基因均为具有生物学合理性的候选靶基因，可为心肌肥厚通路的研究提供全新的科学见解。