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: 8729004
• 负责人: Paras Kumar Mishra
• 金额: $ 36.87万
• 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 2018-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8729004
• 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; Fibrosis; Flow Cytometry; Functional disorder; G-Protein-Coupled Receptors; Gases; Gel; Gelatin; Gelatinase B; Glucose; Goals; Heart; Heart Contractilities; Heart Hypertrophy; Heart failure; High Pressure Liquid Chromatography; Homocysteine; Homocystine; Hydrogen Sulfide; Hyperhomocysteinemia; Hypertrophy; In Situ; Insulin; Ions; Left ventricular structure; Lyase; MMP9 gene; Measures; Mediating; Metabolic; MicroRNAs; Motivation; Mouse Strains; Mus; Muscle Cells; Muscle Contraction; Myocardial; 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; diabetic; diet and exercise; glucose metabolism; improved; novel; oxidant gases; pressure; public health relevance; 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(由申请者提供)：具体目标：缺乏锻炼动力是肥胖和2型糖尿病(T2D)的标志。高脂饮食(HFD)是肥胖的主要原因，而T2D损害心肌细胞的收缩能力，导致心力衰竭。刺激2-肾上腺素能受体(2-AR)可引起心脏收缩，减轻心功能障碍。同型半胱氨酸(Hcy)水平升高称为高同型半胱氨酸血症(HHcy，一种并存疾病)，与糖尿病患者的心力衰竭有关。同型半胱氨酸与2-AR竞争和对抗。该项目的长期目标是了解2-AR和Hcy轴在糖尿病中的作用。同型半胱氨酸是通过胱硫醚合成酶(CBS)和胱硫醚？裂解酶(CSE)。在糖尿病中，CBS和CSE水平受到抑制，从而诱导同型同型半胱氨酸，从而损害硫化氢的形成。硫化氢是AKT(一种参与葡萄糖代谢的抗氧化剂)的诱导剂，AKT在糖尿病中表达下调。我们已经证明，在糖尿病心肌细胞中，H_2S可诱导一种被称为Gs(Inducer of？2-AR)的刺激性G蛋白偶联受体。另一方面，HHcy使Gs减弱。然而，运动减轻了HHcy，并上调了T2D中的2-AR。此外，运动和沙丁胺醇(2-AR激动剂)在缓解糖尿病心肌细胞收缩功能障碍方面具有协同作用。然而，潜在的机制尚不清楚。我们已经证明，在糖尿病中，HHcy激活MMP9，从而诱导心脏纤维化，损害心肌收缩能力。此外，调节心肌纤维化和肥厚的microRNA-133a(miR-133a)在糖尿病心脏中得到缓解。我们的初步研究表明，HHcy(CBS+/-小鼠)和HFD治疗可减弱心肌2-AR和miR-133a，而运动和硫化氢可减轻这种衰减。运动和沙丁胺醇对糖尿病AKT和Gs的诱导有协同作用。转基因表达的2-AR(2-ARTg)可减轻HFD所致的心肌纤维化。同时，去除MMP9基因可改善HFD所致的收缩功能障碍。HFD治疗的WT和CBS+/-小鼠都有左心功能障碍和收缩能力受损，运动训练可以缓解这种情况。HHcy和HFD还下调肌内质网ATPase 2a(SERCA2a；调节肌肉收缩期间的钙通量)，运动和硫化氢可以改善这一点。该方案的中心假设是，在HFD诱导的糖尿病中，运动不耐受部分是由于HHcy抑制2-AR和Gs，下调AKT和miR-133a，并诱导MMP9导致心肌细胞收缩功能障碍。运动和硫化氢通过减轻HHcy和改善糖尿病患者的收缩功能障碍来诱导2-AR和Gs(图1)。我们将通过以下三个具体目标来验证这一假设：具体目标#1：确定糖尿病患者的高同型半胱氨酸血症是否会减弱2-AR，运动和硫化氢是否可以缓解这种减弱。假设：糖尿病时，2-AR下调，Hcy升高，运动和硫化氢诱导2-AR，降低Hcy水平。特定目的#2：确定糖尿病和运动中高同型半胱氨酸血症是否减弱AKT和miR-133a，并诱导MMP9，而硫化氢可改善这种减弱和诱导。假设：在糖尿病中，升高的Hcy水平抑制AKT和miR-133a，并诱导MMP9。运动和硫化氢通过降低同型半胱氨酸水平诱导糖尿病大鼠心脏AKT，降低MMP9水平。具体目的#3：确定糖尿病患者高同型半胱氨酸血症是否损害心肌细胞的收缩功能，运动和硫化氢可缓解收缩功能障碍。假设：在糖尿病患者，Hcy和MMP9升高，而2-AR和AKT减弱，导致收缩功能障碍，运动和硫化氢改善这些水平，减轻收缩功能障碍。这些研究将阐明同型半胱氨酸介导的糖尿病抑制2-AR的机制，以及2-AR激动剂、运动和硫化氢在糖尿病并发症中的心脏保护作用。