Cardiac Sarcoplasmic Reticulum Calcium Cycling Proteins

心脏肌浆网钙循环蛋白

• 批准号: 8989140
• 负责人: Evangelia G Kranias
• 金额: $ 39.5万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-02-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8989140
• 关键词: ATP phosphohydrolase; ATP2A2; Address; Adrenergic Agents; Adrenergic Receptor; Aging; Aging-Related Process; Animal Model; Apoptosis; Apoptotic; Binding; Biochemical; Ca(2+)-Transporting ATPase; Calcium; Cardiac; Cardiac Myocytes; Cardiac Output; Cause of Death; Cell Death; Cell Survival; Characteristics; Complement; Complex; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Cytoprotection; Depressed mood; Deterioration; Development; Enzymes; Equilibrium; Etiology; Functional disorder; Gene Transfer; Goals; Growth; Health; Heart; Heart Diseases; Heart failure; Human; Human Characteristics; Human Genetics; Injury; Lead; Macromolecular Complexes; Mediating; Methodology; Molecular; Molecular Chaperones; Mus; Muscle relaxation phase; Mutation; Myocardial Infarction; Myocardial Ischemia; Myocardial dysfunction; Myocardium; Pathway interactions; Phosphoproteins; Phosphorylation; Physiological; Pilot Projects; Play; Process; Property; Protein Dephosphorylation; Protein Kinase; Protein phosphatase; Proteins; Pump; Recombinants; Regulation; Research; Role; SERCA2a; Sarcoplasmic Reticulum; Scheme; Signal Transduction; Stress; System; Testing; Therapeutic; Time; Ventricular Remodeling; Western World; base; clinically relevant; disability; fighting; genetic variant; heat-shock proteins 20; hemodynamics; inhibitor/antagonist; innovation; insight; meetings; mouse model; mutant; new therapeutic target; novel; pathological aging; phospholamban; programs; protein phosphatase inhibitor-1; research study; response; symptom treatment; therapeutic target; uptake

DESCRIPTION (provided by applicant): Abnormal Ca-cycling, which is a universal characteristic of experimental and human heart failure, is partially due to impaired calcium sequestration into the sarcoplasmic reticulum (SR). SR calcium uptake is mediated by a Ca2+-ATPase (SERCA2), whose activity is reversibly regulated by phospholamban (PLN). Dephosphorylated phospholamban inhibits SERCA2 and phosphorylation relieves this inhibition. In human and experimental heart failure, phospholamban is highly dephosphorylated, due to increased SR protein phosphatase activity, resulting in higher inhibition of SERCA2 and cardiac deterioration. However, our initial simple view of a PLN/SERCA2 complex has been modified by our recent identification of a regulatome consisting of SERCA2, PLN, the regulatory subunit of protein phosphatase 1 (RGL), that anchors this enzyme to PLN, and the two regulators of protein phosphatase 1 (PP1): inhibitor-1 and the small heat shock protein 20 (Hsp20). Hsp20 physically interacts with PP1 and inhibits its activity, resulting in increased PLN phosphorylation and contractility. Hsp20 is also an anti-apoptotic protein protecting the heart against stress-induced injury. Our hypothesis is that Hsp20 is a fundamental regulator of calcium cycling and cell survival in the heart. Alterations in the levels or activity of Hsp20 will lead to disruption f these processes, impacting cardiac remodeling. Indeed, a human mutant of Hsp20 abrogates its stimulatory effects on Ca-cycling and cardioprotection. The innovation of this proposal is the firs identification of a Hsp20/PP1/RGL/PLN/SERCA2 interactome. Our goal is to define the triggers and mechanisms that disrupt the function of this SR regulatome in response to aging and clinically relevant stress with specific emphasis on the newly-discovered regulator, Hsp20. Hsp20 is also phosphorylated by the ¿-adrenergic axis but the significance of this phosphorylation remains elusive. Accordingly, our Aims will provide a first comprehensive characterization of the: 1) molecular mechanisms by which Hsp20 regulates PP1 activity, the downstream substrates and its interaction with inhibitor-1; 2) functional role of PKA-phosphorylation of Hsp20 in regulation of contractility and cell survival, impacting the processes of aging and cardiac remodeling, following myocardial ischemia; 3) therapeutic potential of Hsp20 in inhibition of cardiac dysfunction and pathological growth; and 4) pathways underlying abrogation of the Hsp20 beneficial effects on contractility and cardioprotection elicited by the human S10F- Hsp20 mutant. We will employ an integrative approach using molecular, biochemical and physiological methodology. Our pilot studies are exciting and the proposed experiments are feasible and highly relevant, since the levels and activity of protein phosphatase 1 are significantly increased in failing hearts. The findings will provide fundamental insights into the mechanisms regulating the PP1/PLN/SERCA axis, remodeling and apoptosis with emphasis in the pathophysiology of heart failure and may reveal Hsp20 as a new target to enhance both contractility and cell survival in the stressed heart.

描述（由申请方提供）：异常钙循环是实验性和人类心力衰竭的普遍特征，部分原因是肌浆网（SR）中的钙螯合受损。SR钙摄取由Ca 2 +-ATP酶（SERCA 2）介导，其活性由受磷蛋白（PLN）可逆调节。去磷酸化的受磷蛋白抑制SERCA 2，磷酸化解除这种抑制。在人类和实验性心力衰竭中，由于SR蛋白磷酸酶活性增加，受磷蛋白高度去磷酸化，导致SERCA 2的抑制作用更高，心脏恶化。然而，我们最初简单的看法PLN/SERCA 2复合物已被我们最近鉴定的一个regulatome组成的SERCA 2，PLN，蛋白磷酸酶1（RGL）的调节亚基，锚定这种酶的PLN，和蛋白磷酸酶1（PP 1）的两个监管机构：抑制剂-1和小热休克蛋白20（Hsp 20）修改。Hsp 20与PP 1物理相互作用并抑制其活性，导致PLN磷酸化增加 和收缩性。Hsp 20也是一种抗凋亡蛋白，保护心脏免受应激诱导的损伤。我们的假设是，热休克蛋白20是一个基本的调节钙循环和细胞存活的心脏。Hsp 20水平或活性的改变将导致这些过程的中断，影响心脏重塑。事实上，Hsp 20的人类突变体消除了其对Ca循环和心脏保护的刺激作用。本发明的创新之处在于首次鉴定了Hsp 20/PP 1/RGL/PLN/SERCA 2相互作用组。我们的目标是确定触发器和机制，破坏这个SR调节子的功能，以应对衰老和临床相关的压力，特别强调新发现的调节器，Hsp 20。Hsp 20也被肾上腺素能轴磷酸化，但这种磷酸化的意义仍然难以捉摸。因此，我们的目的将提供第一个全面的表征：1）分子机制，其中Hsp 20调节PP 1活性，下游底物及其与抑制剂-1的相互作用; 2）功能作用的Hsp 20的PKA磷酸化的收缩和细胞存活的调节，影响衰老和心脏重塑的过程中，心肌缺血后; 3）Hsp 20在抑制心脏功能障碍和病理性生长中的治疗潜力;和4）消除Hsp 20对由人S10 F-Hsp 20突变体引起的收缩性和心脏保护的有益作用的潜在途径。我们将采用分子，生物化学和生理学方法的综合方法。我们的初步研究是令人兴奋的，所提出的实验是可行的和高度相关的，因为蛋白磷酸酶1的水平和活性在衰竭的心脏中显著增加。这些发现将为调节PP 1/PLN/SERCA轴，重塑和凋亡的机制提供基本见解，重点是心力衰竭的病理生理学，并可能揭示Hsp 20作为一个新的靶点，以增强应激心脏的收缩力和细胞存活。