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: 8262636
• 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/8262636
• 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和死亡的主要原因。交感神经活动增加是心力衰竭患者的中心特征。心肌细胞凋亡导致的心肌细胞损失在心力衰竭的进展中起重要作用。2-肾上腺素能受体（2-AR）的刺激增加心肌细胞在体外和体内的凋亡。刺激22-AR和抑制性G蛋白（Gi）可防止2-AR刺激的细胞凋亡。最近，我们提供的证据表明，糖原合成酶激酶-32（GSK-32）的激活在2-AR刺激的细胞凋亡中通过线粒体死亡途径发挥促凋亡作用。然而，在心肌细胞中，GSK-32的激活和凋亡的线粒体死亡途径所涉及的分子信号在很大程度上是未知的。内质网（ER或心肌细胞中的肌浆网）是蛋白质折叠、钙储存和钙信号传导的主要场所。错误折叠蛋白的积累和钙稳态的改变引起的内质网应激可触发细胞凋亡。我们最近的初步数据表明，2-AR刺激诱导ER应激在体外在成年心肌细胞和在体内在心脏中，证明了增加表达的GRP-78（ER应激的传感器）和Gadd 153（一种转录因子诱导的ER应激），和激活caspase-12（一种蛋白酶，在ER应激诱导的细胞凋亡中发挥核心作用）。在心肌梗死（MI）后心脏中还观察到GRP-78和Gadd 153的表达增加以及caspase-12的活化。GSK-32的抑制抑制了2-AR刺激的Gadd 153水平的增加。众所周知的药理学ER应激物（布雷菲德菌素A、毒胡萝卜素和衣霉素）激活GSK-32并增加心肌细胞凋亡。Salubrinal，已知保护细胞免受ER应激，在体外抑制2-AR刺激的心肌细胞凋亡增加。用salubrinal输注/治疗小鼠降低了2-AR刺激和MI诱导的左心室功能障碍和心脏中心肌细胞凋亡的程度。这些观察结果导致了我们的中心假设，即2-AR刺激的ER应激诱导激活GSK-32，GSK-32的激活通过增强ER应激和涉及线粒体死亡途径在2-AR刺激的细胞凋亡中起促凋亡作用。特异性目的1的研究集中在了解导致ER应激和心肌细胞凋亡的近端信号通路。具体目标2将使用Gadd 153基因敲除小鼠研究ER应激在2-AR刺激和MI后细胞凋亡和心肌重塑中的体内作用。具体目标3将利用药理学、腺病毒和siRNA等策略，明确内质网应激在GSK-32激活中的作用，并深入了解活性GSK-32增强内质网应激、激活线粒体死亡途径的机制。具体目标4将使用具有显性阴性GSK-32的心脏特异性过表达的转基因小鼠来研究GSK-32在2-AR刺激和MI后心肌细胞凋亡和心肌重塑中的作用。研究内质网应激在心肌细胞凋亡和心肌重塑中的作用，可能为心力衰竭的治疗提供新的治疗策略。 公共卫生相关性： 心力衰竭是退伍军人发病和死亡的主要原因。已知交感神经活动增加会对心脏产生不良影响。最近的研究表明，2-肾上腺素能受体（2-AR）阻滞剂治疗可提高慢性心力衰竭患者的生存率，减少住院率。这为心力衰竭的治疗增加了2-AR阻滞剂。尽管提高了生存率，但疾病过程在影响慢性心脏病患者的发病率和死亡率方面仍然是突出的。该项目的目标是了解心力衰竭期间交感神经活动增加引发的细胞内信号。因此，研究内质网应激在2-AR刺激和心肌梗死后心肌细胞凋亡和心肌重塑中的作用可能会发现治疗心力衰竭的新治疗策略。