Ca2+ signaling mechanisms in cardiac fibrosis

心脏纤维化中的 Ca2 信号传导机制

• 批准号: 6968687
• 负责人: Lixia Yue
• 金额: $ 35.86万
• 依托单位: UNIVERSITY OF CONNECTICUT SCH OF MED/DNT
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-06-15 至 2010-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6968687
• 关键词: acidosis; calcium channel; calcium flux; calcium indicator; cell proliferation; collagen; fibroblasts; fibrogenesis; fibrosis; genetically modified animals; heart cell; heart disorder; hydrogen peroxide; laboratory mouse; molecular pathology; oxidative stress; voltage /patch clamp

DESCRIPTION (provided by applicant): Cardiac fibrosis is a major biological determinant in a variety of cardiac diseases including hypertrophy, heart failure, severe arrhythmias and sudden cardiac death. Early interference with fibroblast proliferation to limit fibrosis should be able to prevent fibrogenesis from further perpetuating cardiac diseases. However, Ca2+ signaling mechanisms in cardiac fibroblasts (CFs) have remained elusive. Our long-term goal is to investigate the Ca2+ signaling mechanisms in CFs and their potential roles in fibrotic heart diseases. We have previously cloned a novel bi-functional Ca2+-permeable ion channel TRPM7. Our recent preliminary data showed that: 1) TRPM7 is likely the molecular basis of native TRPM7L, the only Ca2+-permeable ion channel identified in the CFs to date; 2) TRPM7 inward currents can be drastically enhanced by a decrease in extracellular pH; 3) oxidative stress significantly increased TRPM7 inward currents; 4) chronic exposure to TGFb1 up-regulates TRPM7 expression in CFs. Given that acidosis, oxidative stress, and TGFb1 are potent stimuli in initiating fibrogenesis during myocardial injury/infarction, we hypothesize that TRPM7L is essential for Ca2+ signaling in CFs, and plays important roles in myocardial ischemia/infarction initiated fibrogenesis. We propose to: 1) determine if TRPM7 is the molecular basis of TRPM7L, and if TRPM7L underlies Ca2+ signaling mechanisms in CFs under oxidative stress and acidosis stimuli; 2) investigate if chronic fibrogenesis stimuli up-regulate TRPM7L; 3) determine if TRPM7L is essential for CFs' functions in responses to fibrogenesis stimuli. Patch-clamp, Ca2+ imaging, biochemical methods and gene knock-down will be used in this project to reveal the potential roles of TRPM7L-mediated Ca2+ signals in fibrogenesis cascade events. The results of the proposed studies will lead to a future in vivo study which is designed to evaluate potential roles of TRPM7 in cardiac fibrosis using TRPM7 knock out mice, and will ultimately provide clinical insights into therapeutic approaches for fibrosis associated cardiac diseases.

描述（由申请人提供）：心脏纤维化是多种心脏病的主要生物决定因素，包括肥厚、心力衰竭、严重心律失常和心源性猝死。早期干扰成纤维细胞增殖以限制纤维化应该能够防止纤维化进一步导致心脏病。然而，心脏成纤维细胞 (CF) 中的 Ca2+ 信号传导机制仍然难以捉摸。我们的长期目标是研究 CF 中的 Ca2+ 信号传导机制及其在纤维化心脏病中的潜在作用。我们之前克隆了一种新型双功能Ca2+渗透离子通道TRPM7。我们最近的初步数据表明：1）TRPM7可能是天然TRPM7L的分子基础，TRPM7L是迄今为止在CF中发现的唯一Ca2+渗透性离子通道； 2）TRPM7内向电流可以通过细胞外pH值的降低而急剧增强； 3）氧化应激显着增加TRPM7内向电流； 4) 长期暴露于TGFb1会上调CF中TRPM7的表达。鉴于酸中毒、氧化应激和 TGFb1 是心肌损伤/梗塞期间启动纤维发生的有效刺激因素，我们假设 TRPM7L 对于 CF 中的 Ca2+ 信号转导至关重要，并且在心肌缺血/梗塞启动的纤维发生中发挥重要作用。我们建议：1）确定TRPM7是否是TRPM7L的分子基础，以及TRPM7L是否是氧化应激和酸中毒刺激下CF中Ca2+信号传导机制的基础； 2) 研究慢性纤维发生刺激是否上调TRPM7L； 3) 确定 TRPM7L 是否对于 CF 响应纤维发生刺激的功能至关重要。该项目将使用膜片钳、Ca2+成像、生化方法和基因敲低来揭示TRPM7L介导的Ca2+信号在纤维发生级联事件中的潜在作用。拟议研究的结果将导致未来的体内研究，旨在使用 TRPM7 敲除小鼠评估 TRPM7 在心脏纤维化中的潜在作用，并最终为纤维化相关心脏疾病的治疗方法提供临床见解。