Defining the Role of FHL5, a Novel Hypertension Associated Gene in Smooth Muscle Cells

摘要 高血压，一种由血压慢性升高定义的疾病，是最重要的疾病之一， 心血管疾病的遗传风险因素。高血压的全基因组关联研究 我提供了一个无偏见的调查有关的基因座血压调节，其中许多港口基因 它们聚集成调节平滑肌细胞（SMC）表型的功能通路。作为最 平滑肌细胞是健康血管壁中丰富的细胞类型，通过协调收缩调节血管张力 和放松.为了应对环境压力，SMC去分化并促进致病性细胞因子的产生。 血管重塑，增加血管张力。这些基因座的功能特征，可以揭示 SMC失调的新见解，并为新药候选人提供信息。一个这样的高血压位点， UFL 1-FHL 5在血管壁中的预测作用，也与多种血管疾病相关，包括 冠状动脉疾病、心肌梗塞和偏头痛。统计精细映射方法涉及 FHL 5是UFL 1-FHL 5基因座上的首选候选基因。FHL 5表达在动脉组织中富集， 特别是在血管壁的收缩性SMC和周细胞中。FHL 5是Four and Half LIM结构域的成员 家族，其包括蛋白质FHL 1、FHL 2和FHL 3，其作为转录调节因子起作用， 转录因子，SRF和CREB 1在骨骼肌和心肌组织中的表达。FHL 5，研究最少的 该家族的成员，通过激活CREB 1靶基因参与静脉内膜增生。所以我 假设血管疾病相关遗传变异降低FHL 5表达， 作为一个关键的辅因子激活血管壁中的收缩SMC途径。目标1中的研究将 通过识别关键的FHL 5调控机制， 元素我将在表观遗传学上激活假定的增强子， 评估FHL 5基因表达、SMC收缩性、肌动蛋白细胞骨架组织的变化 和细胞内钙水平。在目标2中，我将阐明FHL 5蛋白的下游功能作用， 使用高分辨率、低输入的Cleavage Under绘制其在人冠状动脉组织中的结合位点 靶向和核酸酶释放（CUT&RUN）方法。我将FHL 5结合位点与SRF交叉， 在匹配的组织样本中的CREB 1结合位点，以确定不同FHL 5 转录复合物我还将确定删除驻留在细胞中的顶级FHL 5调控元件的影响。 高血压位点对SMC功能的影响。总之，在这项研究中，我将描述一种新的高血压相关的 基因座，并确定这种辅助因子在SMC生物学中的作用。这些研究也可以为发展提供信息， 靶向血管壁相关通路的抗高血压治疗，以规避多种血管疾病 并解决诊所中的重大差距。

ABSTRACT Hypertension, a condition defined by a chronic elevation in blood pressure is one of the most significant heritable risk factors for cardiovascular disease. Genome wide association studies (GWAS) in hypertension have provided an unbiased survey of loci relevant to blood pressure regulation, many of which harbor genes that cluster into functional pathways that regulate smooth muscle cell (SMC) phenotypes. As the most abundant cell type in the healthy vessel wall, SMCs regulate vascular tone through coordinated contraction and relaxation. In response to environmental stress, SMCs dedifferentiate and contribute to the pathogenic remodeling of the vessel that increases vascular tone. Functional characterization of these loci, may reveal new insights into SMC dysregulation and inform novel drug candidates. One such hypertension locus with a predicted role in the vessel wall, UFL1-FHL5 is also associated with multiple vascular disorders, including coronary artery disease, myocardial infarction, and migraines. Statistical fine-mapping approaches implicate FHL5 as the top candidate gene at the UFL1-FHL5 locus. FHL5 expression is enriched in artery tissues, specifically in contractile SMC and pericytes in the vessel wall. FHL5 is a member of Four and Half LIM domain family, which include proteins FHL1, FHL2, and FHL3 that function as transcriptional regulators for the transcription factors, SRF and CREB1 in skeletal and cardiac muscle tissue. FHL5, the most understudied member of this family, was implicated in vein intimal hyperplasia by activating CREB1 target genes. Thus, I hypothesize that vascular disease associated genetic variation reduces FHL5 expression and that FHL5 functions as a critical cofactor to activate contractile SMC pathways in the vessel wall. Studies in aim 1 will provide insights into the upstream regulatory mechanisms of FHL5 by identifying critical FHL5 regulatory elements. I will epigenetically activate putative enhancers harboring top candidate hypertension variants in primary SMCs and assess changes in FHL5 gene expression, SMC contractility, actin cytoskeletal organization and intracellular calcium levels. In aim 2, I will elucidate the downstream functional role of FHL5 protein by mapping its binding sites in human coronary artery tissues using the high resolution, low input Cleavage Under Target and Release Upon Nuclease (CUT&RUN) method. I will intersect FHL5 binding sites with SRF and CREB1 binding sites in matched tissue samples to determine the pathways regulated by different FHL5 transcriptional complexes. I will also determine the impact of deleting top FHL5 regulatory elements residing in hypertension loci on SMC functions. Overall, in this study I will characterize a novel hypertension associated locus and define the role of this cofactor in SMC biology. These studies may also inform the development of anti-hypertensive therapies targeting vessel wall related pathways to circumvent multiple vascular diseases and address significant gaps in the clinic.