Angiotensin-II, GTPCH1 and 26S Protesomes

血管紧张素-II、GTPCH1 和 26S 蛋白酶体

基本信息

批准号：
7644122
负责人：
MING-HUI ZOU
金额：
$ 36.63万
依托单位：
UNIVERSITY OF OKLAHOMA HLTH SCIENCES CTR
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-08-01 至 2014-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7644122
关键词：
26S proteasome Acetates Angiotensin II Animal Model Animals Arginine Atherosclerosis Biological Availability Biology Biopterin Blood Pressure Blood Vessels Blood flow Brain Cardiovascular Diseases Caspase Cells Clip Complex Coupled Cultured Cells Cysteine DNA Sequence Rearrangement Data Deoxycorticosterone Development Diabetes Mellitus Disease Electrons Endothelial Cells Endothelium Enzymes Equilibrium Experimental Animal Model FDA approved Figs - dietary Forearm Free Radicals Functional disorder GTP Cyclohydrolase I Gene Silencing Goals Goldblatt Syndrome Guanosine Guanosine Triphosphate Health Human Hydrogen Peroxide Hydroxylation Hypertension Hypotension Individual Injury Kidney Knock-out Knowledge Lead Link MG132 Maintenance Malignant Neoplasms Mass Spectrum Analysis Measures Mediating Modality Modeling Modification Molecular Mus Muscle Tonus NADP NADPH Oxidase Nitric Oxide Oxidants Oxidases Oxidative Stress Oxygen PA700 proteasome activator Pathway interactions Patients Peptide Mapping Peroxonitrite Phenylalanine Hydroxylase Post-Translational Protein Processing Production Proteasome Inhibition Proteasome Inhibitor Proteins Reactive Nitrogen Species Reactive Oxygen Species Regulation Role Sepiapterin reductase Signal Pathway Signal Transduction Smooth Muscle Sodium Chloride Stimulus Superoxide Dismutase Superoxides Supplementation System Testing Therapeutic Therapeutic Effect Tissues Transgenic Mice Transgenic Organisms Treatment Protocols Trypsin Tryptophan 5-monooxygenase Tyrosine Tyrosine 3-Monooxygenase Ubiquitin Ubiquitin-Activating Enzymes Ubiquitin-Conjugating Enzymes Ubiquitination Vascular Diseases Vascular Endothelial Cell Vascular System blood pressure regulation cancer therapy cardiovascular risk factor chymotrypsin cofactor diabetic enzyme activity exposed human population human NOS3 protein improved in vitro Model in vivo insight mRNA Expression mouse model multicatalytic endopeptidase complex mutant nitration overexpression oxidation prevent public health relevance sepiapterin tetrahydrobiopterin therapeutic target tripolyphosphate ubiquitin-protein ligase vascular endothelial dysfunction

项目摘要

DESCRIPTION (provided by applicant): Guanosine 5'-triphosphate cyclohydrolase I (GTPCH1) is a homodecameric protein consisting of 25-kDa subunits, which enzyme catalyzes the rearrangement of GTP to dihydroneopterin triphosphate, a species subsequently converted to tetrahydrobiopterins (BH4) through the sequential action of 6-pyruvoyltetrahydrobiopterin synthase and sepiapterin reductase. In contrast to the latter two enzymes, GTPCH1 is the rate-limiting enzyme in most tissues, making it the major determinant of intracellular BH4 content. GTPCH1 is constitutively expressed in vascular cells; however, whether GTPCH1 is critical for the maintenance of BH4 levels in these cells is unknown. Several recent studies suggest that BH4 deficiency is responsible for endothelial nitric oxide synthase (eNOS) uncoupling during hypertension, as seen by the finding that hypertension and related eNOS uncoupling are effectively prevented by co- administration of sepiapterin, a precursor for BH4. BH4 supplementation or increased BH4 synthesis by GTPCH1 restores BH4 levels and normalizes eNOS function in the deoxycorticosterone acetate (DOCA)-salt hypertensive mice. GTPCH1 activity, as well as BH4 levels, is reduced in these mice. However, the in vivo cause-effect relationship between eNOS uncoupling and GTPCH1, which is critical for eNOS-mediated protection of endothelial function, has yet to be investigated. In particular, it is unclear how pathological stimuli such as hypertension reduce GTPCH1 levels and how stimuli such as angiotensin-II (Ang II) and hypertension modulate proteasome function. Our exciting new preliminary data have led us to hypothesize that Ang II, via oxidants such as ONOO-, increases 26S proteasome-mediated degradation of GTPCH1, resulting in BH4 deficiency, eNOS uncoupling, and the elevation of blood pressure. This central hypothesis will be tested in three interrelated specific aims by using a combination of experimental approaches including purified proteins, cultured cells, and several models of hypertension in vivo. The proposed studies are significant, as they will deepen our understanding of the upstream regulation of BH4 levels, the contribution of oxidative stress and ubiquitin-proteasome systems in the development of vascular injury, and the contribution of oxidative stress in blood pressure regulation. In particular, these studies will provide clues as to the therapeutic effects of MG132, a proteasome inhibitor that was recently approved by the FDA for cancer therapy. PUBLIC HEALTH RELEVANCE: The aim of the current application is to dissect the molecular mechanisms for vascular endothelial dysfunction in hypertension. Completion of three interrelated aims will provide new knowledge regarding the upstream regulation of GTPCH, a rate-limiting enzyme for BH4 levels as well as the contributions of oxidative stress and ubiquitin- proteasome systems in the development of vascular injury and the contribution of oxidative stress in blood pressure regulation. Once such knowledge is gained, significant advances in our fundamental understanding of GTPCH1 regulation of vascular biology in health and disease can be expected. In addition, there is the promise that new modalities can be developed to test the true potential of the GTPCH1/BH4 pathway as a therapeutic target in vascular diseases associated with hypertension and if proteasome inhibitor, MG132, a recent FDA-approved therapeutic regimen for cancer, can be used in treating vascular endothelial dysfunction in hypertension.

描述（由申请人提供）：鸟苷 5'-三磷酸环水解酶 I (GTPCH1) 是一种由 25-kDa 亚基组成的同型十聚体蛋白，该酶催化 GTP 重排为三磷酸二氢新蝶呤，随后通过6-丙酮酰四氢生物蝶呤合酶和墨蝶呤的连续作用还原酶。与后两种酶相比，GTPCH1 是大多数组织中的限速酶，使其成为细胞内 BH4 含量的主要决定因素。 GTPCH1 在血管细胞中组成型表达；然而，GTPCH1 是否对于维持这些细胞中的 BH4 水平至关重要尚不清楚。最近的几项研究表明，BH4 缺乏是高血压期间内皮一氧化氮合酶 (eNOS) 解偶联的原因，这一发现表明，共同施用墨蝶呤（BH4 的前体）可有效预防高血压和相关的 eNOS 解偶联。在醋酸脱氧皮质酮 (DOCA) 盐高血压小鼠中，补充 BH4 或通过 GTPCH1 增加 BH4 合成可恢复 BH4 水平并使 eNOS 功能正常化。这些小鼠中 GTPCH1 活性以及 BH4 水平均降低。然而，eNOS 解偶联和 GTPCH1 之间的体内因果关系尚未得到研究，而 GTPCH1 对于 eNOS 介导的内皮功能保护至关重要。特别是，目前尚不清楚高血压等病理刺激如何降低 GTPCH1 水平，以及血管紧张素 II (Ang II) 和高血压等刺激如何调节蛋白酶体功能。我们令人兴奋的新初步数据使我们推测，Ang II 通过 ONOO- 等氧化剂增加 26S 蛋白酶体介导的 GTPCH1 降解，导致 BH4 缺乏、eNOS 解偶联和血压升高。这一中心假设将通过结合使用纯化蛋白质、培养细胞和几种体内高血压模型等实验方法，在三个相互关联的具体目标中进行测试。拟议的研究意义重大，因为它们将加深我们对 BH4 水平上游调节、氧化应激和泛素蛋白酶体系统在血管损伤发展中的作用以及氧化应激在血压调节中的作用的理解。特别是，这些研究将为 MG132 的治疗效果提供线索，MG132 是一种蛋白酶体抑制剂，最近被 FDA 批准用于癌症治疗。公共健康相关性：当前应用的目的是剖析高血压血管内皮功能障碍的分子机制。三个相互关联的目标的完成将提供关于 GTPCH（BH4 水平限速酶）上游调节的新知识，以及氧化应激和泛素-蛋白酶体系统在血管损伤发展中的贡献以及氧化应激在血管损伤中的贡献。血压调节。一旦获得了这些知识，我们对 GTPCH1 在健康和疾病中血管生物学调节的基本理解就有望取得重大进展。此外，有望开发出新的方法来测试 GTPCH1/BH4 通路作为与高血压相关的血管疾病的治疗靶点的真正潜力，以及蛋白酶体抑制剂 MG132（最近 FDA 批准的一种癌症治疗方案），可用于治疗高血压的血管内皮功能障碍。