Cytoglobin: A stress-responsive hemoprotein modulating cardiomyocyte survival

细胞珠蛋白：一种调节心肌细胞存活的应激反应性血红素蛋白

• 批准号: 8296262
• 负责人: PRADEEP P.A. MAMMEN
• 金额: $ 39.7万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-05-01 至 2017-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8296262
• 关键词: Acute; Adult; Apoptosis; Apoptotic; Biological Assay; Brain Hypoxia-Ischemia; Cardiac; Cardiac Myocytes; Cardiovascular system; Cell Death; Cell Survival; Cell physiology; Development; Dilated Cardiomyopathy; Disease; Gene Targeting; Goals; Heart; Heart failure; Hemeproteins; Homeostasis; Hypertension; In Vitro; Knock-out; Knockout Mice; Laboratories; Longevity; Mission; Morbidity - disease rate; Mus; Muscle Cells; Myocardial Infarction; Outcome; Oxidation-Reduction; Oxidative Stress; Patients; Play; Process; Protein p53; Proteins; Public Health; Recombinant Proteins; Recombinants; Reperfusion Injury; Research; Research Project Grants; Role; Signal Pathway; Stress; Testing; Transcript; Tumor Suppressor Proteins; United States National Institutes of Health; Work; candidate identification; chromatin immunoprecipitation; improved; in vitro activity; in vivo; injured; innovation; insight; mortality; mouse model; novel; novel therapeutic intervention; overexpression; pressure; prevent; promoter; protein protein interaction; reconstitution; research study

DESCRIPTION (provided by applicant): Heart failure is the major cause of cardiovascular mortality in the US and often develops as a consequence of maladaptive cardiac remodeling due to hypertension or a myocardial infarction (MI). Although over the past decade we have made major advances in the treatment of heart failure, the morbidity and mortality associated with this disease remains high. Thus, the identification of candidate proteins and signaling pathways that prevent or reverse the process of maladaptive cardiac remodeling is a major goal in the pursuit of new treatment approaches for improving the quality and longevity of heart failure patients. Our laboratory recently identified cytoglobin (Cygb) as a stress-responsive hemoprotein and its levels increase in the adult heart under a variety of stress conditions (i.e. hypoxia, ischemia, and pressure-overload). Overexpression of Cygb in cultured myocytes protects them from oxidative stress, while knockdown of Cygb results in increased apoptotic cell death. Initially, we postulated that Cygb protects myocytes via anti-oxidative mechanisms inherent to all hemoproteins; however, we now have extensive evidence that Cygb is also directly involved in regulating the transcriptional activity of the tumor suppressor protein p53. W have found a reciprocal relationship between transcript levels of Cygb and a number of p53-target genes. Chromatin immunoprecipitation experiments demonstrate co-occupancy of p53 and Cygb at classic p53 target promoters. Using recombinant proteins we show a direct protein-protein interaction between the two proteins. Importantly, recombinant Cygb inhibits p53 transcriptional activity in vitro reconstituted transcriptional assays. Finally, we have developed conditional Cygb knockout mouse model and have preliminary studies demonstrating that acute cardiac-specific loss of Cygb leads to a dilated cardiomyopathy. Likewise, mice born with cardiac-specific deletion of Cygb develop a more pronounced dilated cardiomyopathy after ischemia-reperfusion (I/R) injury as compared to injured control mice. Our central hypothesis is that Cygb contributes to cardiomyocyte survival via both anti-oxidative and p53-dependent mechanisms. We propose the following three specific aims to test this hypothesis: Specific Aim 1: Define the role of cytoglobin in maintaining cardiomyocyte homeostasis. Specific Aim 2: Define the role of cytoglobin during maladaptive cardiac remodeling. Specific Aim 3: Define the significance of the cytoglobin-p53 interaction for cardiomyocyte survival. The successful completion of our proposed study will provide insight into a novel signaling pathway that regulates cardiomyocyte survival and may provide opportunities for the development of novel therapeutic approaches to prevent and/or reverse heart failure. Thus, the proposed NIH R01 Research Grant Application is relevant to and in keeping with the missions of both the NIH and NHBLI. PUBLIC HEALTH RELEVANCE: The experiments proposed in this NIH R01 Research Grant Application have significant relevance to the public health of the nation. This study is innovative because it proposes that cytoglobin, a novel stress-responsive cardiac hemoprotein, plays an important role in promoting cardiomyocyte survival and thus may regulate the development of maladaptive cardiac remodeling. Ultimately, an enhanced understanding of the cellular function of cytoglobin within the heart will provide opportunities for the development of novel therapeutic approaches to prevent and/or reverse the development of maladaptive cardiac remodeling and thus improve the outcomes of heart failure patients.

描述（由申请人提供）：心力衰竭是美国心血管死亡的主要原因，通常是由于高血压或心肌梗死（MI）引起的心脏重构不适应的结果。虽然在过去的十年中，我们在治疗心力衰竭方面取得了重大进展，但与此疾病相关的发病率和死亡率仍然很高。因此，鉴定候选蛋白和信号通路，防止或逆转心脏不适应重塑的过程是追求新的治疗方法，以提高心力衰竭患者的质量和寿命的主要目标。我们的实验室最近发现细胞红蛋白（Cygb）是一种应激反应性血红蛋白，其水平在成人心脏中在各种应激条件下（即缺氧、缺血和压力过载）升高。在培养的肌细胞中，Cygb的过表达可以保护它们免受氧化应激，而Cygb的下调会导致凋亡细胞死亡增加。最初，我们假设Cygb通过所有血红蛋白固有的抗氧化机制保护肌细胞；然而，我们现在有大量证据表明Cygb也直接参与调节肿瘤抑制蛋白p53的转录活性。我们发现Cygb转录水平与许多p53靶基因之间存在反比关系。染色质免疫沉淀实验证实p53和Cygb在经典p53靶启动子上共存在。利用重组蛋白，我们展示了两种蛋白之间的直接蛋白相互作用。重要的是，重组Cygb在体外重组转录试验中抑制p53的转录活性。最后，我们建立了条件Cygb敲除小鼠模型，并进行了初步研究，表明急性心脏特异性Cygb缺失导致扩张性心肌病。同样，与受伤的对照组小鼠相比，出生时具有心脏特异性Cygb缺失的小鼠在缺血再灌注（I/R）损伤后出现更明显的扩张性心肌病。我们的中心假设是Cygb通过抗氧化和p53依赖机制促进心肌细胞存活。我们提出以下三个具体目标来验证这一假设：具体目标1：确定细胞红蛋白在维持心肌细胞稳态中的作用。特异性目的2：明确细胞红蛋白在不适应心脏重构中的作用。特异性目的3：明确细胞珠蛋白-p53相互作用对心肌细胞存活的意义。这项研究的成功完成将为研究调节心肌细胞存活的新信号通路提供洞见，并可能为开发预防和/或逆转心力衰竭的新治疗方法提供机会。因此，拟议的NIH R01研究资助申请与NIH和NHBLI的使命相关并保持一致。