Brain-targeted ACE2 over-expression on angiotensin-II-mediated hypertension

描述（由申请人提供）：肾素-血管紧张素系统（RAS）是健康和疾病中心血管（CV）和肾功能的主要调节因子。RAS组分在中央CV控制区的活性和表达升高，以及高血压伴中央病变或血管紧张素II（Ang-II）拮抗剂给药的衰减支持了以下观点：在几种遗传和实验模型中，功能亢进的脑RAS可能参与高血压的发病机制。到目前为止，普遍的假设是Ang-II是这个系统的主要参与者。RAS的一个新成员ACE 2（血管紧张素转换酶2型）已在与CV功能相关的器官和组织（例如心脏、肾脏、血管）中鉴定，似乎是缓冲过量Ang-II的反调节途径的一部分。我们最近在参与血压（BP）中枢调节的大脑区域中发现了ACE 2蛋白，并表明它受到RAS其他成分的调节。此外，我们最近观察到，ACE 2在穹窿下器官（SFO）的过度表达，显着降低了升压反应，中央管理的Ang-II在小鼠中，并减少氧化应激细胞。这些观察结果增加了ACE 2在产生生物活性肽如Ang-（1-7）中的作用，为在正常和病理生理状态下进一步探索大脑提供了理论基础。在本研究中，我们假设中枢ACE 2在高血压中起主要的代偿作用; ACE 2的过表达将促进Ang-（1-7）的形成和Ang-II的降解，从而加强代偿机制，预防高血压和相关的氧化应激。利用我们在生理基因组学方面的专业知识，一门研究基因操作的生理后果的科学，结合清醒小鼠中CV功能的最新记录和分析，我们建议研究慢性ACE 2过度表达对神经源性高血压发展的后果。使用具有脑靶向ACE 2过表达的新的基因工程小鼠模型，我们将：1）建立脑靶向ACE 2过表达在神经性高血压中的功能后果。2)确定SFO和RVLM在Syn-ACE 2转基因小鼠中ACE 2介导的高血压降低中的作用及其激活的分子后果。3)确定ACE 2过表达对Ang-II和Ang-（1-7）受体信号通路的影响。我们相信，这种独特的模型将使我们能够确定中枢ACE 2在神经源性高血压中的体内生理作用。ACE 2在BP调节中的有益作用的证据可能导致开发新的治疗方法以及更好地利用现有治疗方法治疗高血压和其他CV疾病。公共卫生相关性：在心血管疾病中，高血压的全球患病率估计可能高达10亿人，每年约有710万人死于高血压。使用转基因小鼠，本申请将描述一种新酶ACE 2预防高血压发展的能力。如果得到证实，ACE 2可能成为治疗高血压和其他心血管疾病的新靶点。

DESCRIPTION (provided by applicant): The renin-angiotensin system (RAS) is a major regulator of cardiovascular (CV) and renal function in health and disease. Elevated activity and expression of RAS components in central CV control regions and attenuation of the Hypertension with central lesions or administration of angiotensin-II (Ang-II) antagonists have supported the notion that a hyper-functioning brain RAS may be involved in the pathogenesis of Hypertension in several genetic and experimental models. Until now, the common assumption was that Ang-II served as the main actor of this system. A new member of the RAS, ACE2 (angiotensin converting enzyme type 2) has been identified in organs and tissues related to CV function (e.g. heart, kidney, vessels) and appears to be part of a counter-regulatory pathway buffering the excess of Ang-II. We recently identified the ACE2 protein in brain regions involved in the central regulation of blood pressure (BP) and showed that it is regulated by other components of the RAS. In addition, we recently observed that ACE2 over-expression in the subfornical organ (SFO) dramatically reduces the pressor response to central administration of Ang-II in mice and reduces oxidative stress in cells. These observations added to the role of ACE2 in the generation of biologically active peptides like Ang-(1-7), supply a rationale for further explorations in the brain in the face of normal and pathophysiological states. In this proposal, we hypothesize that central ACE2 plays a major compensatory role during Hypertension; ACE2 over-expression will promote Ang-(1-7) formation and Ang-II degradation, resulting in the reinforcement of compensatory mechanisms and preventing Hypertension and the associated oxidative stress. Taking advantage of our expertise in physiological genomics, a science that studies the physiological consequences of gene manipulation, combined to state of the art recording and analysis of CV function in conscious mice, we propose to investigate the consequences of chronic ACE2 over-expression on the development of neurogenic Hypertension. Using a new genetically-engineered mouse model, with brain-targeted ACE2 over- expression, we will: 1) Establish the functional consequences of brain-targeted ACE2 over-expression in neurogenic hypertension. 2) Identify the role of the SFO and RVLM in the ACE2-mediated reduction of Hypertension in Syn- ACE2 transgenic mice and the molecular consequences of their activation. 3) Determine the effects of ACE2 over-expression on Ang-II and Ang-(1-7) receptors signaling pathways. We believe that this unique model will allow us to determine the physiological role of central ACE2 in- vivo in neurogenic Hypertension. Evidence of a beneficial role of ACE2 in BP regulation could lead to the development of new therapeutics as well as a better utilization of existing therapeutics for the treatment of Hypertension and other CV diseases. PUBLIC HEALTH RELEVANCE: Among cardiovascular diseases, worldwide prevalence estimates for Hypertension may be as much as 1 billion individuals, and approximately 7.1 million deaths per year may be attributable to Hypertension. Using transgenic mice, this application will describe the ability of a new enzyme, ACE2, to prevent the development of Hypertension. If confirmed, ACE2 could become a new target for the treatment of Hypertension and other cardiovascular diseases.