ER stress: role in myocyte apoptosis and myocardial remodeling

内质网应激：在心肌细胞凋亡和心肌重塑中的作用

• 批准号: 7931473
• 负责人: KRISHNA SINGH
• 金额: --
• 依托单位: JAMES H QUILLEN VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7931473
• 关键词: Address; Adrenergic Receptor; Adult; Adverse effects; Affect; Apoptosis; Apoptotic; Brefeldin A; Calcium; Calcium Signaling; Cardiac; Cardiac Myocytes; Cells; Cessation of life; Chronic; Data; Disease; Dominant-Negative Mutation; Endoplasmic Reticulum; GRP gene; Glycogen Synthase Kinases; Heart; Heart Diseases; Heart failure; Heat shock proteins; Homeostasis; Hospitalization; In Vitro; Infusion procedures; Inhibitory G-Protein Gi; Isoproterenol; Knockout Mice; Left Ventricular Dysfunction; Mitochondria; Molecular; Morbidity - disease rate; Mus; Muscle Cells; Myocardial Infarction; Pathway interactions; Patients; Peptide Hydrolases; Play; Process; Receptor Signaling; Regulation; Role; Sarcoplasmic Reticulum; Signal Pathway; Signal Transduction; Site; Small Interfering RNA; Stress; Testing; Thapsigargin; Transcriptional Regulation; Transgenic Mice; Tunicamycin; Ventricular Remodeling; Veterans; beta-adrenergic receptor; caspase 12; endoplasmic reticulum stress; improved; in vivo; inhibitor/antagonist; insight; mortality; novel therapeutics; overexpression; protein folding; protein misfolding; sensor; stress protein; stressor; transcription factor; treatment strategy

DESCRIPTION (provided by applicant): Heart failure represents a major cause of morbidity and mortality among veterans. Increased sympathetic activity is a central feature in patients with heart failure. Cardiac myocyte loss due to apoptosis plays an important role in the progression of heart failure. Stimulation of 2-adrenergic receptor (2-AR) increases apoptosis in cardiac myocytes in vitro and in vivo. Stimulation of 22-AR and inhibitory G-protein (Gi) protects against 2-AR-stimulated apoptosis. Recently, we provided evidence that activation of glycogen synthase kinase-32 (GSK-32) plays a pro-apoptotic role in 2-AR- stimulated apoptosis via the involvement of mitochondrial death pathway. However, molecular signals involved in the activation of GSK-32 and mitochondrial death pathway of apoptosis are largely unknown in cardiac myocytes. The endoplasmic reticulum (ER or sarcoplasmic reticulum in cardiac myocytes) is a principal site for protein folding, calcium storage and calcium signaling. ER stress induced by accumulation of misfolded proteins and alterations in calcium homeostasis can trigger apoptosis. Our recent preliminary data demonstrate that 2-AR stimulation induces ER-stress in vitro in adult cardiac myocytes and in vivo in the heart as evidenced by increased expression of GRP-78 (sensor of ER stress) and Gadd153 (a transcription factor induced by ER stress), and activation of caspase-12( a protease which plays a central role in ER stress-induced apoptosis). Increased expression of GRP-78 and Gadd153 and activation of caspase-12 was also observed in the heart following myocardial infarction (MI). Inhibition of GSK-32 inhibited 2-AR-stimulated increases in Gadd153 levels. Well-known pharmacological ER stressors (brefeldin A, thapsigargin and tunicamycin) activated GSK-32 and increased cardiac myocyte apoptosis. Salubrinal, known to protect cells from ER stress, inhibited 2-AR-stimulated increases in cardiac myocyte apoptosis in vitro. Infusion/treatment of mice with salubrinal reduced the extent of 2-AR-stimulated and MI-induced left ventricular dysfunction and cardiac myocyte apoptosis in the heart. These observations have led to our central hypothesis that 2-AR-stimulated induction of ER stress activates GSK-32, and activation of GSK-32 plays a pro-apoptotic role in 2-AR-stimulated apoptosis by augmenting ER stress and involving mitochondrial death pathway. Studies of Specific Aim 1 are focused on understanding the proximal signaling pathway leading to ER stress and cardiac myocyte apoptosis. Specific Aim 2 will use Gadd153 knockout mice to investigate the in vivo role of ER stress in apoptosis and myocardial remodeling following 2-AR stimulation and MI. Specific aim 3 will use pharmacologic, adenoviral and siRNA strategies to define the role of ER stress in the activation of GSK-32, and get an insight into the mechanism by which active GSK-32 augments ER stress and activates mitochondrial death pathway. Specific aim 4 will use transgenic mice with cardiac-specific overexpression of dominant negative GSK-32 to investigate the role of GSK-32 in cardiac myocyte apoptosis and myocardial remodeling following 2-AR stimulation and MI. The proposed studies investigating the role of ER stress in cardiac myocyte apoptosis and myocardial remodeling may uncover novel therapeutic strategies for the treatment of heart failure. PUBLIC HEALTH RELEVANCE: Heart failure represents a major cause of morbidity and mortality among veterans. Increased sympathetic activity is known to cause adverse effects in the heart. Recent studies have shown that 2-adrenergic receptor (2-AR) blocker therapy improves survival and reduces hospitalizations in patients with chronic heart failure. This has added 2-AR blockers to the therapy of heart failure. Despite the improved survival, the disease process is still pre-eminent in affecting the morbidity and mortality of patients with chronic heart disease. The objectives of this project are directed towards understanding the intracellular signals initiated by increased sympathetic activity during heart failure. Thus, the proposed studies investigating the role of endoplasmic reticulum stress in cardiac myocyte apoptosis and myocardial remodeling following 2-AR stimulation and myocardial infarction may uncover novel therapeutic strategies for the treatment of heart failure.

描述（由申请人提供）： 心力衰竭是退伍军人发病率和死亡率的主要原因。同情活动增加是心力衰竭患者的核心特征。由于凋亡而导致的心肌细胞丧失在心力衰竭进展中起重要作用。刺激2-肾上腺素受体（2-AR）会在体外和体内增加心肌细胞的凋亡。刺激22AR和抑制性G蛋白（GI）可预防2AR刺激的凋亡。最近，我们提供了证据表明，糖原合酶激酶-32（GSK-32）的激活通过线粒体死亡途径的参与，在2-AR刺激的凋亡中起促凋亡的作用。然而，在心肌细胞中，参与GSK-32激活和线粒体死亡途径的激活和线粒体死亡途径的分子信号在心肌细胞中基本上是未知的。内质网（心肌细胞中的ER或肌浆网）是蛋白质折叠，钙储存和钙信号传导的主要部位。由错误折叠蛋白的积累引起的ER应激和钙稳态的改变会引发凋亡。 Our recent preliminary data demonstrate that 2-AR stimulation induces ER-stress in vitro in adult cardiac myocytes and in vivo in the heart as evidenced by increased expression of GRP-78 (sensor of ER stress) and Gadd153 (a transcription factor induced by ER stress), and activation of caspase-12( a protease which plays a central role in ER stress-induced apoptosis).在心肌梗塞（MI）之后，在心脏中也观察到了GRP-78和GADD153的表达增加以及Caspase-12的激活。 GSK-32的抑制作用抑制了GADD153水平的2AR刺激的增加。众所周知的药理学ER应激源（Brefeldin A，Thapsigargin和Gunicamycin）激活了GSK-32，并增加了心肌细胞凋亡。已知可以保护细胞免受ER胁迫的salubrinal抑制了体外心肌细胞凋亡的2-AR刺激增加。用萨利维拉尼纳尔输注/治疗小鼠可降低心脏中2 AR刺激和MI诱导的左心室功能障碍和心肌细胞凋亡的程度。这些观察结果导致了我们的核心假设，即2 AR刺激的ER应力激活GSK-32，而GSK-32的激活通过增加ER应力和涉及线粒体死亡途径，在2AR刺激的凋亡中起促凋亡的作用。特定目标1的研究集中在理解导致急诊症和心肌细胞凋亡的近端信号传导途径上。具体目标2将使用GADD153敲除小鼠研究2-AR刺激和MI后，ER应激在凋亡和心肌重塑中的体内作用。具体目标3将使用药理，腺病毒和siRNA策略来定义ER应力在GSK-32激活中的作用，并深入了解主动GSK-32增加ER应力并激活线粒体死亡途径的机制。具体目标4将使用具有主要负GSK-32心脏特异性过表达的转基因小鼠，以研究GSK-32在2-AR刺激和MI后GSK-32在心肌细胞凋亡和心肌重塑中的作用。提出的研究研究了质网应激在心肌细胞凋亡和心肌重塑中的作用可能会发现用于治疗心力衰竭的新型治疗策略。 公共卫生相关性： 心力衰竭是退伍军人发病率和死亡率的主要原因。已知同情活动增加会导致心脏不良反应。最近的研究表明，2-肾上腺素受体（2AR）阻滞剂治疗可改善生存率并减少慢性心力衰竭患者的住院治疗。这为心力衰竭的治疗增加了2-AR阻滞剂。尽管生存率提高，但在影响慢性心脏病患者的发病率和死亡率方面，疾病过程仍然是显着的。该项目的目标旨在理解心力衰竭期间的交感神经活动引发的细胞内信号。因此，提出的研究研究了2AR刺激和心肌梗死后，内质网应激在心肌细胞凋亡和心肌重塑中的作用可能会发现新颖的治疗策略以治疗心脏衰竭。