Angiotensin-(1-12). Novel Pathways for Angiotensin Peptide Formation

项目概要/摘要-项目1 心脏血管紧张素II活性增加--由于细胞内或间质中血管紧张素II形成上调， 隔室通过自分泌或旁分泌机制起作用-有助于心脏肥大性重塑， 心律失常和纤维化RAS抑制剂在阻断血管紧张素II介导的不良心脏反应方面效果较差。 由于心肌细胞中的Ang II产生遵循非经典途径， 将血管紧张素原（Aogen）加工成十二肽中间底物Ang-（1-12）。我们进一步 表明，在啮齿类动物和人类之间的Ang-（1-12）代谢是糜酶而不是ACE将Ang-（1-12）转化为 （1-12）直接转化为人心脏组织中的Ang II，并且该过程可以包括另外的步骤，其中 人Aogen可以在转化成Ang-（1-25）之前加工成新鉴定的前体Ang-（1-25）。 12）。人型心肌糜酶，在心肌细胞中表达或被整合到心肌细胞中。 来自活化肥大细胞的细胞，是从Ang-（1-12）和可能的Ang-（1-25）产生Ang II的酶。试点 研究表明激肽释放酶作为切割来自Aogen的Ang-（1-12）的酶的作用。在此基础上，项目1 提出了一个假设，即血管紧张素II介导的不良心脏重塑的结果，从处理 Aogen衍生肽的中间形式通过细胞内形成的或 并入的糜酶。此外，我们认为这些生物转化步骤是物种特异性的。到 为了实现这些目标，我们将确定：目标1，激肽释放酶或激肽释放酶的区室化和作用 WKY和SHR心肌组织Ang-（1-12）产生的家族成员酶及其潜力 在表达人源基因的转基因大鼠模型中心脏Ang-（1-12）产生的水解活性 Aogen [TGR（hAGT）L1623];目的2，Ang-（1-12）和Ang-（1-25）作为心肌细胞Ang-（1-12）和Ang-（1-25）的底物的作用 WKY和SHR与TGR（hAGT）L1623大鼠的II产生;目的3，血流动力学和RAS特征， 负责TGR（hAGT）L1623中Ang-（1-25）和Ang-（1-12）表达的酶。我们还将 评估凝乳酶驱动的心脏血管紧张素II通路是否受到物种特异性的影响， 将人Aogen转基因大鼠与表达人糜酶基因的大鼠杂交。我们的工作将 揭示了新的治疗方法，高血压心脏肥大和纤维化的基础上，非- 典型的心脏血管紧张素II形成。

Project Summary/Abstract - Project 1 Increased cardiac Ang II activity-as a result of upregulated Ang II formation in the intracellular or interstitial compartment acting via autocrine or paracrine mechanisms- contributes to cardiac hypertrophic remodeling, arrhythmias, and fibrosis. RAS inhibitors are less effective in blocking Ang II-mediated adverse cardiac remodeling because Ang II production in cardiac myocytes follows a non-canonical pathway through the processing of angiotensinogen (Aogen) into the dodecapeptide intermediate substrate Ang-(1-12). We further showed that Ang-(1-12) metabolism between rodents and humans is that chymase but not ACE converts Ang- (1-12) directly into Ang II in human heart tissue and that this process may include an additional step in which human Aogen may be processed into a newly identified precursor Ang-(1-25) prior to conversion into Ang-(1- 12). The human form of � cardiac chymase, either expressed in cardiomyocytes or incorporated into these cells from activated mast cells, is the enzyme producing Ang II from Ang-(1-12) and likely Ang-(1-25). Pilot studies suggest a role for kallikrein as the enzyme cleaving Ang-(1-12) from Aogen. On these bases, Project 1 poses the hypothesis that Ang II-mediated adverse cardiac remodeling results from the processing of intermediate forms of Aogen-derived peptides through the hydrolytic activity of intracellularly formed or incorporated chymase. Furthermore, we propose that these biotransformation steps are species-specific. To achieve these objectives we will determine: Aim 1, the compartmentalization and role of kallikrein or a kallikrein family member enzyme in the production of Ang-(1-12) from cardiac Aogen in WKY and SHR and its potential hydrolytic activity in cardiac Ang-(1-12) production in a transgenic rat model expressing the genes from human Aogen [TGR(hAGT)L1623]; Aim 2, the role of Ang-(1-12) and Ang-(1-25) as substrates for cardiomyocyte Ang II production in WKY and SHR versus TGR(hAGT)L1623 rats; Aim 3, the hemodynamic and RAS profile and the enzymes accounting for the expression of Ang-(1-25) and Ang-(1-12) in TGR(hAGT)L1623. We will also assess whether the chymase-driven cardiac Ang II pathway is influenced by species-specificity through the crossing of the human Aogen transgenic rat with a rat expressing the genes for human chymase. Our work will reveal new therapeutic approaches to hypertensive cardiac hypertrophy and fibrosis that are based on non- canonical cardiac Ang II formation.