Intrarenal Angiotensin II generation during Angiotensin II-induced hypertension

该项目的长期目标是建立重要性和基本机制， 介导肾内ACE衍生的Ang II生成对高血压发展的影响， 肾损伤，同时促进申请人过渡到肾脏疾病领域的独立职业生涯。 肾脏拥有肾素-血管紧张素系统的所有成分，因此能够 合成血管紧张素Ⅱ。因为肾脏在体液平衡和血压方面起着重要作用 由于血管紧张素II的调节，肾内血管紧张素II生成的增加可能对血管紧张素II的调节至关重要。 高血压和肾损害的发展，但这尚未确定。以前的研究， 申请人证明来自输注Ang II的小鼠的肾脏显示出血管紧张素原增加 肾素和血管紧张素转换酶（ACE）活性的表达和持续性表明， 存在持续的肾内Ang II生成。 最近的报告提供了证据，血管紧张素II和microRNA之间的功能相互作用。 由于单个microRNA可以调节多个基因的表达，因此在产生 复杂的表型，如高血压和肾损害肾内血管紧张素II调节一个或几个 microRNAs。特别是，microRNA 21（miR-21）在心血管疾病中获得了认可，因为 它参与心肌肥大、凋亡、炎症，并作为某些Ang II作用的介质，但其 在肾脏疾病中的作用尚未确定。因此，要测试的假设是，在Ang II诱导的高血压，肾内ACE衍生的Ang II形成是必需的，以增加Ang II水平， 肾脏，反过来增加钠和水潴留，增加miR-21表达，并导致 高血压和肾损伤的进行性发展。 实验将在杜兰大学生理学系合作进行 来自加利福尼亚州洛杉矶的雪松西奈中心。将使用组织特异性ACE敲除小鼠，以便 解决这一假设，并提出以下具体目标：1）证明小鼠与 肾内血管紧张素II形成受损，作为肾脏中缺乏ACE的结果， 慢性肾衰竭时肾内血管紧张素II含量、钠潴留、血压水平和肾损伤增加 与野生型对照相比，Ang II输注。2)为了证明仅在小鼠中表达ACE， 肾脏出现肾内血管紧张素II含量增加和钠潴留沿着血液 血压水平和肾损伤在慢性输注的ACE底物血管紧张素I。3)证明 miR-21在小鼠肾脏中上调是肾内Ang II生成增加的结果 在血管紧张素II诱导的高血压，这是一个重要的机制， 高血压和肾损伤。

The long-term goals of this project are to establish the importance and underlying mechanisms mediating the effects of intrarenal ACE-derived Ang II generation on the development of hypertension and renal injury while facilitating the applicant¿s transition to an independent career in the field of kidney disease. The kidneys posses all the components of the renin-angiotensin system and therefore are capable of synthesizing Ang II. Because the kidneys play a preponderant role in fluid homeostasis and blood pressure regulation, it is likely that an augmented intrarenal Ang II generation is of cardinal importance for the development of hypertension and renal damage but this has not been determined. Previous studies by the applicant demonstrate that the kidneys from Ang II-infused mice display an augmented angiotensinogen expression and persistence of renin and angiotensin-converting enzyme (ACE) activities that suggest the presence of sustained intrarenal Ang II generation. Recent reports have provided evidence for functional interactions between Ang II and microRNAs. Because a single microRNA can regulate the expression of multiple genes, it is possible that in generating complex phenotypes like hypertension and kidney damage intrarenal Ang II modulates one or several microRNAs. In particular, microRNA 21 (miR-21) has gained recognition in cardiovascular disease because of its involvement in cardiac hypertrophy, apoptosis, inflammation, and as mediator of some Ang II actions, but its role in kidney disease has not been determined. Therefore, the HYPOTHESIS to be tested is that during Ang II-induced hypertension, intrarenal ACE-derived Ang II formation is required in order to augment Ang II levels in the kidney that in turn increase sodium and water retention, increase miR-21 expression, and lead to the progressive development of high blood pressure and renal injury. Experiments will be conducted in the department of Physiology of Tulane University in collaboration with Cedars-Sinai Center from Los Angeles, CA. Tissue-specific ACE knockout mice will be used in order to address this hypothesis and the following SPECIFIC AIMS are proposed: 1) To demonstrate that mice with impaired intrarenal Ang II formation, as a consequence of the absence of ACE in the kidneys, develop lesser increases in intrarenal Ang II content, sodium retention, blood pressure levels and kidney injury during chronic Ang II infusions when compared to wild-type controls. 2) To demonstrate that mice with ACE expression only in the kidneys develop increases in intrarenal Ang II content and sodium retention along with increased blood pressure levels and kidney injury during chronic infusions of the ACE substrate Ang I. 3) To demonstrate that miR-21 is upregulated in the mouse kidney as a consequence of an augmented intrarenal Ang II generation during Ang II-induced hypertension and that this is an important mechanism for the development of hypertension and renal injury.