Lysyl Oxidase Mutations in Cardiovascular Disease

摘要 包括主动脉瘤在内的心血管疾病通常被认为是老年人的疾病。 与环境因素和生活方式选择有关的人口，包括吸烟和肥胖引起的 高脂肪和高盐饮食。然而，20%的受胸主动脉瘤和夹层影响的人， TAAD具有可遗传的形式，通常归因于编码细胞外基质的基因突变 (ECM)有助于血管壁完整性的蛋白质和生长因子。虽然有许多基因 现在被确定为含有遗传形式的TAAD的致病突变，75%的TAAD家族中的致病基因， 这种疾病还没有被发现。我们最近发现了一个病因不明的TAAD家族。 通过全基因组测序，我们确定了赖氨酰氧化酶（LOX）基因的错义突变 （c.893T>G编码p.Met298Arg），其与家族中的动脉瘤表型分离。LOX是一种 催化胺氧化反应的细胞外酶，用于临界交联和成熟 弹性蛋白和胶原蛋白-血管壁中的关键ECM蛋白。 为了了解Lox相关的淋巴瘤性疾病的潜在机制，我们使用了 CRISPR/Cas9基因组编辑系统将人类突变引入小鼠（人类中的M298 R，M292 R 在小鼠中）。对携带M292 R突变的小鼠血管系统的表征证实， 突变确实会导致主动脉瘤的形成。M292 R突变纯合子动物死亡 因为主动脉瘤破裂而死亡然而，对于突变杂合子的动物， 在3个月大时没有发生动脉瘤，但在主动脉壁有破碎的弹性纤维，这表明 当暴露于有害刺激时，突变动物可能倾向于发展血管疾病。在 在这项提议中，我们将利用这种M292 R小鼠模型来表征导致细胞凋亡的变化的机制。 并确定额外的血管壁应力是否会诱发胸主动脉瘤。 此外，我们将确定由突变引起的LOX功能改变的潜在机制， 最终导致动脉瘤形成。将Lox鉴定为家族性TAAD的致病基因不仅 允许我们在临床基因检测过程中筛选Lox，但了解Lox的机制， 突变影响Lox酶功能的研究将为潜在的治疗开发提供深入了解。

ABSTRACT Cardiovascular diseases including aortic aneurysms are generally considered disease of the older population related to environmental factors and life style choices including smoking, and obesity caused by high fat and salt diets. However, 20 percent of individuals affected by thoracic aortic aneurysm and dissections (TAAD) have a heritable form, commonly attributed to mutations in genes that encode for extracellular matrix (ECM) proteins and growth factors that contribute to vascular wall integrity. While there are a number of genes now identified as containing causal mutations for inherited forms of TAAD, causal genes in 75% of families with this disease have not been discovered. We recently identified a family with TAAD with unknown etiology. Through whole genome sequencing, we identified a missense mutation in the lysyl oxidase (LOX) gene (c.893T>G encoding p. Met298Arg) that segregated with the aneurysm phenotype in the family. LOX is an extracellular enzyme that catalyzes the amine oxidation reaction for critical crosslinking and maturation of elastin and collagen- key ECM proteins in the vessel wall. To understand the mechanism underlying Lox-associated aneurysmal disease, we used the CRISPR/Cas9 genome editing system to introduce the human mutation into mice (M298R in humans, M292R in mice). Characterization of the vascular system in mice carrying the M292R mutation confirmed that the mutation does indeed lead to aortic aneurysm formation. Animals homozygous for the M292R mutation died within a few hours of birth due to ruptured aortic aneurysm. Animals heterozygous for the mutation, however, did not develop aneurysms at 3 months of age, but had fragmented elastic fibers in the aorta wall, suggesting that the mutant animals may be predisposed to develop vascular disease when exposed of injurious stimuli. In this proposal, we will utilize this M292R mouse model to characterize mechanisms leading to changes in the arterial wall and determine whether additional vascular wall stress will induce thoracic aortic aneurysms. Furthermore, we will identify mechanisms underlying altered LOX function caused by the mutation that ultimately leads to aneurysm formation. Identification of Lox as a causal gene for familial TAAD will not only allow us to screen for Lox during clinical genetic testing, but understanding the mechanism behind how the mutation affects Lox enzyme function will provide insight into potential therapeutic development.