Intrarenal Angiotensin II generation during Angiotensin II-induced hypertension

这个项目的长期目标是建立重要的基础机制 肾内血管紧张素转换酶衍生的血管紧张素转换酶II在高血压和高血压发病中的作用 同时帮助申请人S在肾脏损伤的同时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.因为肾脏在液体动态平衡和血压中起着主导作用 监管，很可能是一个扩大的肾内血管紧张素II代是至关重要的 高血压和肾脏损害的发展，但这一点尚未确定。之前的研究由 申请人证明，注射血管紧张素II的小鼠的肾脏显示出增强的血管紧张素原。 肾素和血管紧张素转换酶(ACE)活性的表达和持久性提示 存在持续的肾内血管紧张素II代。 最近的报道为Ang II和microRNAs之间的功能相互作用提供了证据。 由于单个microRNA可以调节多个基因的表达，因此有可能在生成 复杂的表型，如高血压和肾损害，肾内Ang II调节一种或几种 MicroRNA。特别是，microRNA 21(miR-21)在心血管疾病中得到了认可，因为 它参与了心肌肥大、细胞凋亡、炎症，并作为一些Ang II活动的中介，但它 在肾脏疾病中的作用尚未确定。因此，需要检验的假设是，在Ang 血管紧张素转换酶诱导的高血压，肾内血管紧张素转换酶衍生的血管紧张素转换酶II的形成是为了增加血管紧张素转换酶II水平 肾脏进而增加钠和水的保持，增加miR-21的表达，并导致 高血压和肾脏损伤的进行性发展。 实验将在杜兰大学生理系合作进行 与加利福尼亚州洛杉矶的锡达斯-西奈中心合作。组织特异性ACE基因敲除小鼠将被用于 针对这一假设，提出了以下具体目标：1)证明小鼠具有 肾内血管紧张素转换酶II的形成受损，由于肾脏中缺乏血管紧张素转换酶，导致较少发生 慢性肾损害时肾内血管紧张素Ⅱ含量、钠滞留、血压水平和肾脏损伤的增加 与野生型对照相比，血管紧张素II输注。2)证明仅在体内表达ACE的小鼠 随着血液的增加，肾脏内血管紧张素Ⅱ的含量和钠的滞留也会增加。 慢性输注血管紧张素转换酶底物时的压力水平和肾脏损伤 由于肾内Ang II代的增加，MIR-21在小鼠肾脏中上调 在血管紧张素转换酶II诱导的高血压过程中，这是血管紧张素Ⅱ诱导的高血压的一个重要机制 高血压和肾脏损伤。

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.