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主要特征。细胞凋亡导致的心肌细胞损失在心力衰竭的进展中起着重要作用。刺激 2-肾上腺素能受体 (2-AR) 可增加体外和体内心肌细胞的凋亡。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) 的激活通过参与线粒体死亡途径在 2-AR 刺激的细胞凋亡中发挥促细胞凋亡作用。然而，心肌细胞中参与 GSK-32 激活和线粒体死亡途径凋亡的分子信号在很大程度上是未知的。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。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引发细胞凋亡。我们最近的初步数据表明，2-AR 刺激在体外成人心肌细胞和体内心脏中诱导 ER 应激，GRP-78（ER 应激传感器）和 Gadd153（ER 诱导的转录因子）表达增加证明了这一点。应激），以及 caspase-12（一种在内质网应激诱导的细胞凋亡中起核心作用的蛋白酶）的激活。心肌梗塞 (MI) 后的心脏中还观察到 GRP-78 和 Gadd153 表达增加以及 caspase-12 激活。抑制 GSK-32 可抑制 2-AR 刺激的 Gadd153 水平增加。众所周知的药理学 ER 应激源（布雷菲德菌素 A、毒胡萝卜素和衣霉素）可激活 GSK-32 并增加心肌细胞凋亡。 Salubrinal 已知可保护细胞免受 ER 应激，在体外可抑制 2-AR 刺激的心肌细胞凋亡增加。小鼠输注/治疗 salubrinal 可降低 2-AR 刺激和 MI 诱导的左心室功能障碍和心脏心肌细胞凋亡的程度。这些观察结果得出我们的中心假设，即 2-AR 刺激的 ER 应激诱导会激活 GSK-32，并且 GSK-32 的激活通过增强 ER 应激并涉及线粒体死亡，在 2-AR 刺激的细胞凋亡中发挥促凋亡作用途径。具体目标 1 的研究重点是了解导致 ER 应激和心肌细胞凋亡的近端信号通路。 Specific Aim 2 将使用 Gadd153 敲除小鼠来研究 2-AR 刺激和 MI 后 ER 应激在细胞凋亡和心肌重塑中的体内作用。具体目标 3 将使用药理学、腺病毒和 siRNA 策略来定义 ER 应激在 GSK-32 激活中的作用，并深入了解活性 GSK-32 增强 ER 应激并激活线粒体死亡途径的机制。具体目标 4 将使用心脏特异性显性失活 GSK-32 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。拟议的研究调查内质网应激在心肌细胞凋亡和心肌重塑中的作用，可能会揭示治疗心力衰竭的新治疗策略。 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。众所周知，交感神经活动的增加会对心脏造成不利影响。最近的研究表明，2-肾上腺素受体 (2-AR) 阻滞剂治疗可提高慢性心力衰竭患者的生存率并减少住院率。这使得2-AR阻滞剂被添加到心力衰竭的治疗中。尽管生存率有所提高，但疾病过程仍然是影响慢性心脏病患者发病率和死亡率的主要因素。该项目的目标是了解心力衰竭期间交感神经活动增加所引发的细胞内信号。因此，所提出的研究调查内质网应激在 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，可能会揭示治疗心力衰竭的新治疗策略。