Exercise and H2S mitigate homocysteine-mediated beta2-adrenergic receptor dysfunc

运动和 H2S 减轻同型半胱氨酸介导的 β2 肾上腺素能受体功能障碍

• 批准号: 8870418
• 负责人: Paras Kumar Mishra
• 金额: $ 37.06万
• 依托单位: UNIVERSITY OF NEBRASKA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8870418
• 关键词: ATP phosphohydrolase; Ablation; Adrenergic Receptor; Affect; Agonist; Albuterol; Antihypertensive Agents; Antioxidants; Attenuated; Binding Sites; Cardiac; Cardiac Myocytes; Co-Immunoprecipitations; Complications of Diabetes Mellitus; Confocal Microscopy; Cystathionine; Devices; Diabetes Mellitus; Diabetic mouse; Diet; Echocardiography; Endoplasmic Reticulum; Enzymes; Exercise; FVB Mouse; Fatty acid glycerol esters; Flow Cytometry; Functional disorder; G-Protein-Coupled Receptors; Gases; Gel; Gelatin; Gelatinase B; Glucose; Goals; Health; Heart; Heart Contractilities; Heart Hypertrophy; Heart failure; High Pressure Liquid Chromatography; Homocysteine; Homocystine; Hydrogen Sulfide; Hyperhomocysteinemia; In Situ; Insulin; Ions; Left ventricular structure; Lyase; MMP9 gene; Measures; Mediating; Metabolic; MicroRNAs; Motivation; Mouse Strains; Mus; Muscle Cells; Muscle Contraction; Myocardial; Myocardial dysfunction; Obese Mice; Obesity; Optics; Patients; Plasma; Plasmids; Play; Proto-Oncogene Proteins c-akt; Radio; Reporting; Role; Small Interfering RNA; Telemetry; Testing; Training; Transfection; Transgenic Organisms; Western Blotting; Western World; attenuation; coronary fibrosis; diabetic; diet and exercise; glucose metabolism; improved; novel; oxidant gases; pressure; receptor; release of sequestered calcium ion into cytoplasm; sodium sulfide

DESCRIPTION (provided by applicant): Specific Aims: Lack of motivation to exercise is the hallmark of obesity and type2 diabetes (T2D). High fat diet (HFD) is the major cause of obesity and T2D that impair contractility of cardiomyocytes leading to heart failure. The stimulation of �2-adrenergic receptors (�2-AR) induces contractility and mitigates cardiac dysfunction. Elevated level of homocysteine (Hcy) called hyperhomocysteinemia (HHcy, a co-morbid condition) is associated with heart failure in diabetes. Hcy competes with and antagonizes �2-AR. The long term goal of the project is to understand the role of �2- AR and Hcy axis in diabetes. HHcy is ameliorated by conversion of Hcy to H2S (an anti-hypertensive, vasorelaxing, and anti-oxidant gas) by cystathionine � synthase (CBS) and cystathionine ? lyase (CSE). In diabetes, the levels of CBS and CSE are suppressed that induces HHcy and thereby impairs formation of H2S. H2S is an inducer of AKT (an anti-oxidant involved in glucose metabolism) and AKT is down regulated in diabetes. We have shown that H2S induces a stimulatory G-protein couple receptor called Gs (inducer of �2-AR) in diabetic cardiomyocytes. On the other hand, HHcy attenuates Gs. However, exercise mitigates HHcy and up regulates �2-AR in T2D. Also, exercise and salbutamol (�2-AR agonist) have synergistic effect on mitigation of contractile dysfunction in diabetic cardiomyocytes. However, the underlying mechanism is unclear. We have shown that in diabetes, HHcy activates MMP9 that induces cardiac fibrosis and impairs myocardial contractility. Also, microRNA-133a (miR-133a) that regulates cardiac fibrosis and hypertrophy is attenuated in diabetic hearts. Our preliminary studies show that HHcy (CBS+/- mice) and HFD treatment attenuate myocardial �2-AR and miR-133a, whereas exercise and H2S mitigate this attenuation. Exercise and salbutamol have synergistic effect on induction of AKT and Gs in diabetes. The transgenic expression of �2-AR (�2-ARTg) mitigates HFD induced cardiac fibrosis. Also, ablation of MMP9 gene ameliorates HFD induced contractile dysfunction. Both HFD treated WT and CBS+/- mice have left ventricle dysfunction and impaired contractility, which is mitigated by exercise training. HHcy and HFD also down regulates sarco-endoplasmic reticulum ATPase 2a (serca2a; regulates calcium flux during muscle contraction), which is improved by exercise and H2S. The central hypothesis of the proposal is that in HFD induced diabetes, the intolerance to exercise is, in part, due to attenuation of �2-AR and Gs by HHcy that down regulates AKT and miR-133a and induces MMP9 causing myocytes contractile dysfunction. The exercise and H2S induce �2-AR and Gs by mitigating HHcy and ameliorate contractile dysfunction in diabetes (Figure 1). We will test this hypothesis by following three specific aims: Specific Aim#1: To determine whether the �2-AR is attenuated by hyperhomocysteinemia in diabetes and exercise and H2S mitigate this attenuation. Hypothesis: In diabetes, �2-AR is down regulated and Hcy is elevated, and exercise and H2S induce �2-AR and decrease Hcy level. Specific Aim#2: To determine whether the AKT and miR-133a are attenuated and MMP9 is induced by hyperhomocysteinemia in diabetes and exercise and H2S ameliorate this attenuation and induction. Hypothesis: In diabetes, the elevated level of Hcy inhibits AKT and miR-133a and induces MMP9. Exercise and H2S induce AKT and attenuate MMP9 by decreasing Hcy level in diabetic hearts. Specific Aim#3: To determine whether the contractility of cardiomyocytes is impaired by hyperhomocysteinemia in diabetes and exercise and H2S mitigate the contractile dysfunction. Hypothesis: In diabetes, Hcy and MMP9 are elevated while �2-AR and AKT are attenuated leading to contractile dysfunction, and exercise and H2S ameliorate these levels and mitigate contractile dysfunction. These studies will elucidate the mechanism of homocysteine-mediated attenuation of �2-AR in diabetes and cardio-protective role of �2-AR agonist, exercise and H2S in diabetic complications.

描述（由申请人提供）： 具体目标：缺乏运动动力是肥胖和 2 型糖尿病 (T2D) 的标志。高脂肪饮食（HFD）是肥胖和 T2D 的主要原因，它会损害心肌细胞的收缩性，导致心力衰竭。刺激β2-肾上腺素能受体（β2-AR）可诱导收缩性并减轻心脏功能障碍。同型半胱氨酸 (Hcy) 水平升高，称为高同型半胱氨酸血症（HHcy，一种并发症），与糖尿病心力衰竭有关。 Hcy 与 2-AR 竞争并对抗。该项目的长期目标是了解 2-AR 和 Hcy 轴在糖尿病中的作用。 HHcy 通过胱硫醚合成酶 (CBS) 和胱硫醚 ? 将 Hcy 转化为 H2S（一种抗高血压、舒张血管和抗氧化气体）而得到改善。裂解酶（CSE）。在糖尿病中，CBS 和 CSE 的水平受到抑制，从而诱导 HHcy，从而损害 H2S 的形成。 H2S 是 AKT（一种参与葡萄糖代谢的抗氧化剂）的诱导剂，AKT 在糖尿病中下调。我们已经证明，H2S 在糖尿病心肌细胞中诱导一种称为 Gs（β2-AR 诱导剂）的刺激性 G 蛋白偶联受体。另一方面，HHcy 会减弱 Gs。然而，运动会降低 T2D 患者的 HHcy 水平并上调 β2-AR。此外，运动和沙丁胺醇（α2-AR激动剂）对减轻糖尿病心肌细胞的收缩功能障碍具有协同作用。然而，其根本机制尚不清楚。我们已经证明，在糖尿病中，HHcy 会激活 MMP9，从而诱导心脏纤维化并损害心肌收缩力。此外，调节心脏纤维化和肥大的 microRNA-133a (miR-133a) 在糖尿病心脏中减弱。我们的初步研究表明，HHcy（CBS+/- 小鼠）和 HFD 治疗可减弱心肌 α2-AR 和 miR-133a，而运动和 H2S 可减轻这种减弱。运动和沙丁胺醇对糖尿病中 AKT 和 Gs 的诱导具有协同作用。 �2-AR (�2-ARTg) 的转基因表达可减轻 HFD 诱导的心脏纤维化。此外，MMP9 基因的消除可改善 HFD 引起的收缩功能障碍。 HFD 治疗的 WT 和 CBS+/- 小鼠均出现左心室功能障碍和收缩力受损，但运动训练可以缓解这种情况。 HHcy 和 HFD 还下调肌内质网 ATP 酶 2a（serca2a；调节肌肉收缩期间的钙通量），运动和 H2S 可以改善这种情况。该提案的核心假设是，在 HFD 诱发的糖尿病中，对运动的不耐受部分是由于 HHcy 减弱 2-AR 和 Gs，从而下调 AKT 和 miR-133a 并诱导 MMP9 导致心肌细胞收缩功能障碍。运动和 H2S 通过减轻 HHcy 诱导 2-AR 和 Gs 并改善糖尿病患者的收缩功能障碍（图 1）。我们将通过以下三个具体目标来检验这一假设： 具体目标#1：确定 2-AR 是否会因糖尿病和运动中的高同型半胱氨酸血症而减弱，而 H2S 会减轻这种减弱。假设：在糖尿病中，β2-AR 下调且 Hcy 升高，运动和 H2S 诱导 β2-AR 并降低 Hcy 水平。具体目标#2：确定糖尿病和运动中的高同型半胱氨酸血症是否会减弱 AKT 和 miR-133a，并且诱导 MMP9，而 H2S 会改善这种减弱和诱导。假设：在糖尿病中，Hcy 水平升高会抑制 AKT 和 miR-133a 并诱导 MMP9。运动和 H2S 通过降低糖尿病心脏中的 Hcy 水平来诱导 AKT 并减弱 MMP9。具体目标#3：确定糖尿病患者的高同型半胱氨酸血症是否会损害心肌细胞的收缩力，而运动和 H2S 是否会减轻收缩功能障碍。假设：在糖尿病中，Hcy 和 MMP9 升高，而 2-AR 和 AKT 减弱，导致收缩功能障碍，运动和 H2S 可以改善这些水平并减轻收缩功能障碍。这些研究将阐明糖尿病中同型半胱氨酸介导的β2-AR减弱机制以及β2-AR激动剂、运动和H2S在糖尿病并发症中的心脏保护作用。