Mechanotransduction in myocardial adaptation to ischemia

心肌适应缺血的力学转导

• 批准号: 9124926
• 负责人: Charles K Thodeti
• 金额: $ 37.9万
• 依托单位: NORTHEAST OHIO MEDICAL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-15 至 2019-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9124926
• 关键词: Actins; Area; Attenuated; Biological Assay; Biomedical Engineering; Calcium; Cardiac; Cardiovascular system; Cells; Cessation of life; Chemicals; Cicatrix; Clinical Management; Cytoskeleton; Deposition; Discipline; Echocardiography; Extracellular Matrix; Fibroblasts; Fibrosis; Fluorescence Resonance Energy Transfer; Foundations; Functional disorder; Gel; Growth; Health; Heart; Heart Diseases; Heart failure; Hypertrophy; Image; Infarction; Injection of therapeutic agent; Injury; Ion Channel; Ischemia; Knockout Mice; Laboratories; Lead; Luciferases; MAP Kinase Gene; MAPK14 gene; Mechanical Stress; Mechanics; Mediating; Mediation; Mediator of activation protein; Membrane; Microscopy; Molecular; Mus; Myocardial; Myocardial Infarction; Myocardial Ischemia; Myocardium; Myofibroblast; Pathway interactions; Patients; Play; Positioning Attribute; Production; Proteins; Reporter; Research; Research Personnel; Rho-associated kinase; Role; Rupture; Serum Response Factor; Signal Transduction; Stretching; Testing; Therapeutic; Time; Tissues; Vanilloid; Wild Type Mouse; Work; Wound Healing; cardiac repair; coronary fibrosis; factor A; heart function; interdisciplinary approach; mitogen-activated protein kinase p38; multi-photon; myocardin; novel; novel therapeutic intervention; patch clamp; prevent; receptor; research study; response; rho; therapeutic development; therapeutic target; trafficking; transcription factor; treatment strategy

DESCRIPTION (provided by applicant): Ischemic heart disease (IHD) is the major underlying cause of myocardial infarction, scarring, and hypertrophy leading to heart failure. The myocardium adapts to this ischemic injury by inducing scar formation which is crucial to stabilize the ischemic area and prevent rupture; however, cardiac fibrosis often develops in these patients over time. Therefore, post-MI adaptation of the heart is crucial for its long term functio and clinical management of cardiac fibrosis post-MI presents a major challenge. The differentiation of CFs to myofibroblasts is a critical first step following myocardial infarction ad disproportionate production and prolonged survival of myofibroblasts can generate excessive ECM protein deposition leading to pathological fibrosis. Although TGFb1 and mechanical stress (generated by ECM stiffness) are recognized as major mediators of myofibroblast differentiation, the molecular signals that coordinate these soluble and mechanical signals are still elusive. The long-term objective of this proposal is to understand the mechanotransduction mechanisms of cardiac fibroblast differentiation to myofibroblasts. Our preliminary results demonstrate that the mechanosensitve ion channel TRPV4 (Transient Receptor Potential Vanilloid 4) is required for TGF-b1- induced differentiation of CF into myoFibs. Importantly, we have found that TGF-b1-induced myofibroblast differentiation required a high stiffness matrix, a response that was attenuated by TRPV4 blockade. TGF-b1 treatment enhanced TRPV4 expression, membrane translocation (via p38 MAPK) and activity in CFs. Further, we found that TRPV4 activates a mechanosensitive transcription factor, MRTF-A (myocardin related transcription factor-A), via Rho-dependent mechanism. Importantly, we found that when subjected to MI, cardiac function was preserved and fibrosis was reduced in the TRPV4KO mice compared to wild type mice. Finally, injection of Rho activator, CNF1 in to the hearts of TRPV4KO mice caused cardiac fibrosis in post-MI hearts confirming the role of this mechanotransduction pathway in the mediation of cardiac fibrosis. Our working hypothesis is that the mechanosensitive ion channel, TRPV4, regulates cardiac fibroblast differentiation to myofibroblasts through the integration of chemical (TGF-b1) and mechanical signaling. We will test this hypothesis in the following specific aims 1) Define the molecular mechanisms by which TGF-b1 regulates TRPV4 expression, trafficking, and activity in cardiac fibroblasts 2) Interrogate the mechanotransduction mechanisms by which TRPV4 mediates cardiac fibroblast differentiation and 3) Determine a causative role of TRPV4 in cardiac fibrosis following myocardial infarction. TRPV4 channels have not been studied as potential therapeutic targets for myocardial infarction. Our proposed studies will establish TRPV4 as an integrator of mechanical and chemical signals required for myocardial adaptation to ischemia and may open entirely new avenues for development therapeutics for myocardial ischemia and pathological cardiac fibrosis.

描述(申请人提供)：缺血性心脏病(IHD)是心肌梗死、疤痕形成和肥大导致心力衰竭的主要潜在原因。心肌通过诱导瘢痕形成来适应这种缺血损伤，而瘢痕形成对稳定缺血区和防止破裂至关重要；然而，随着时间的推移，这些患者往往会出现心脏纤维化。因此，心肌梗死后心脏的适应性对其长期功能至关重要，心肌梗死后心脏纤维化的临床处理是一项重大挑战。CFs向肌成纤维细胞的分化是心肌梗死后的关键第一步，不成比例的产生和延长的肌成纤维细胞存活可产生过量的ECM蛋白沉积，导致病理性纤维化。尽管TGFb1和机械应力(由ECM硬度产生)被认为是肌成纤维细胞分化的主要介质，但协调这些可溶性信号和机械信号的分子信号仍然难以捉摸。该建议的长期目标是了解心脏成纤维细胞分化为肌成纤维细胞的机械转导机制。我们的初步结果表明，机械感觉离子通道TRPV4(瞬时受体电位香草素4)是转化生长因子-β1诱导的CFs分化为myoFibs所必需的。重要的是，我们发现转化生长因子-β1诱导的肌成纤维细胞分化需要高硬度的基质，这种反应被TRPV4阻断而减弱。经转化生长因子-β1处理后，CFs的TRPV4表达、膜转位(通过p38MAPK)和活性均增强。此外，我们还发现TRPV4通过Rho依赖的机制激活机械敏感性转录因子MRTF-A(myocardin Related转录因子-A)。重要的是，我们发现当遭受心肌梗死时，与野生型小鼠相比，TRPV4KO小鼠的心功能得到了保护，纤维化得到了减轻。最后，将Rho激活剂CNF1注入TRPV4KO小鼠的心脏，导致心肌梗死后心脏纤维化，证实了这一机械转导途径在介导心肌纤维化中的作用。我们的工作假设是，机械敏感离子通道TRPV4通过整合化学信号(转化生长因子-β1)和机械信号来调节心脏成纤维细胞向肌成纤维细胞的分化。我们将在以下特定目标中验证这一假说：1)确定转化生长因子-β1调节心脏成纤维细胞中TRPV4表达、运输和活性的分子机制2)询问机械转导 TRPV4介导心脏成纤维细胞分化的机制：3)确定TRPV4在心肌梗死后心脏纤维化中的致病作用。TRPV4通道尚未被作为心肌梗死的潜在治疗靶点进行研究。我们拟议的研究将使TRPV4成为心肌适应缺血所需的机械和化学信号的整合因子，并可能为开发心肌缺血和病理性心脏纤维化的治疗药物开辟全新的途径。