Unmasking Conduction Deficits in the Scn5a+/- Mouse Model of Brugada Syndrome

揭示 Scn5a/Brugada 综合征小鼠模型中的传导缺陷

• 批准号: 10516016
• 负责人: Grace Anna Bonson
• 金额: $ 3.69万
• 依托单位: VIRGINIA POLYTECHNIC INST AND ST UNIV
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-10 至 2023-05-09
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10516016
• 关键词: Action Potentials; Adhesions; Animals; Arrhythmia; Attenuated; Biomedical Research; Brugada syndrome; Calcium; Cardiac Electrophysiologic Techniques; Case Study; Cell membrane; Cells; Child; Clinical; Conflict (Psychology); Connexin 43; Connexins; Coupling; Development; Diagnosis; Diagnostic; Disease; Edema; Electrocardiogram; Electrolytes; Electrophysiology (science); Equilibrium; Event; Experimental Designs; Fluorescence; Genes; Genetic; Goals; Heart; Heart Abnormalities; Hyponatremia; Image; Intercalated disc; Investigation; Lead; Learning; Mannitol; Maps; Measures; Mediating; Membrane Potentials; Mentors; Mentorship; Microelectrodes; Modeling; Monitor; Mus; Mutation; Nature; Optics; Pathologic; Pathology; Patients; Pattern; Peptides; Perfusion; Pharmaceutical Preparations; Physiological; Plasma; Population; Predictive Value; Reporting; Research; Research Institute; Research Personnel; Resolution; Rest; Risk; Route; Side; Sodium; Sodium Channel; Symptoms; Syndrome; Techniques; Testing; Training; Transmission Electron Microscopy; Universities; Variant; Ventricular; Ventricular Arrhythmia; Virginia; Washington; Width; Wild Type Mouse; Work; career; clinically relevant; diagnostic tool; driving force; experience; experimental study; extracellular; high risk; in vivo; interstitial; loss of function mutation; mouse model; novel; novel diagnostics; prevent; response; skills; spatiotemporal; structural heart disease; sudden cardiac death; theories; therapy development; tool; voltage; voltage sensitive dye; young adult

Project Summary Brugada Syndrome (BrS) is a rare but severe disease that can lead to arrhythmias and sudden cardiac death in children and young adults with no structural heart disease. The most prominent genetic contributor to this disease is loss of function mutations in scn5a, the gene encoding the voltage gated sodium channel, Nav1.5. However, many BrS patients with these mutations are asymptomatic until experiencing a major arrhythmic event, making this syndrome “concealed” in nature. While diagnostic drug challenges exist for those at high risk of becoming symptomatic, they have low positive predictive value. The relationship between loss of Nav1.5, conduction slowing, and arrhythmias is well established, and it is possible that concealed conduction slowing is the underlying driver of BrS pathology. This proposal aims to utilize a scn5a heterozygous mouse model of BrS to determine whether modulation of ephaptic coupling within the intact heart can unmask BrS-associated conduction slowing. In Aim 1, ephaptic coupling will be manipulated by altering the width of the perinexus, a nanodomain of the intercalated disk, in the isolated, Langendorff-perfused Scn5a+/- and WT mouse heart. Conduction velocity will be assessed using optical mapping, wherein the intact heart is perfused with a voltage sensitive dye and imaged with high spatio-temporal resolution. Dr. Rob Gourdie at Virginia Tech will provide technical mentorship while the fellow learns the technique of transmission electron microscopy. She will then employ this technique to confirm changes in perinexal width. The long-term goal for this component is to develop a novel diagnostic for BrS. Aim 2 of this proposal will investigate whether hyponatremia can unmask greater conduction slowing in the Sn5a+/- mouse heart relative to its WT counterpart. Again, the fellow will utilize optical mapping to assess conduction in response to this change. She has recently collaborated with the lab of Dr. Matt Kay at George Washington University to learn how to build and implement floating microelectrodes, and will continue to work with this group in order establish this technique in Dr. Poelzing's lab at the Fralin Biomedical Research Institute at Virginia Tech Carilion (FBRI). The floating microelectrode technique will provide stable and direct electrophysiological measures from intact, beating mouse hearts in response to hyponatremia. The long- term goal for this component is to assess whether monitoring plasma sodium and calcium levels in BrS patients may be an effective approach to prevent clinical manifestations of BrS. Together, the results of this proposal may suggest new avenues of investigation for novel diagnostics and treatments for BrS. All of the proposed experiments will be conducted at FBRI, the collaborative biomedical research campus of Virginia Tech. With the support of her sponsor and mentoring team, this project will also be the basis to expand and strengthen the fellow's technical and professional skill sets in order to prepare her for the next step in her career plan as a postdoctoral associate en route to becoming an independent researcher in the field of cardiac electrophysiology.

项目概要 布鲁格达综合征 (BrS) 是一种罕见但严重的疾病，可导致心律失常和心源性猝死。 无结构性心脏病的儿童和年轻人。导致这种疾病的最显着的遗传因素 是 scn5a 的功能缺失突变，scn5a 是编码电压门控钠通道 Nav1.5 的基因。然而， 许多携带这些突变的 BrS 患者在发生重大心律失常事件之前都是无症状的，这使得 这种综合症本质上是“隐藏的”。虽然对于那些高风险人群来说，诊断药物存在挑战 有症状，其阳性预测值较低。 Nav1.5损失、传导之间的关系 减慢，心律失常已明确，隐匿性传导减慢可能是 BrS 病理学的根本驱动因素。该提案旨在利用 BrS 的 scn5a 杂合小鼠模型来 确定完整心脏内的触觉耦合的调节是否可以揭示 BrS 相关性 传导减慢。在目标 1 中，将通过改变会神经带的宽度来操纵蜈蚣耦合， Langendorff 灌注的分离的 Scn5a+/- 和 WT 小鼠心脏中的闰盘纳米结构域。 将使用光学测绘评估传导速度，其中用电压灌注完整的心脏 敏感染料并以高时空分辨率成像。弗吉尼亚理工大学的 Rob Gourdie 博士将提供 技术指导，同时研究员学习透射电子显微镜技术。那时她会 采用这种技术来确认会周宽度的变化。该组件的长期目标是开发 一种新的 BrS 诊断方法。该提案的目标 2 将调查低钠血症是否可以揭示更大的问题 相对于 WT 小鼠心脏，Sn5a+/- 小鼠心脏的传导减慢。同样，该研究员将利用光学 映射以评估响应这种变化的传导。她最近与 Matt 博士的实验室合作 凯在乔治华盛顿大学学习如何构建和实施浮动微电极，并将 继续与该小组合作，以便在弗拉林生物医学中心 Poelzing 博士的实验室中建立这项技术 弗吉尼亚理工大学 Carilion 研究所 (FBRI)。浮动微电极技术将提供稳定和 从完整的、跳动的小鼠心脏对低钠血症的反应中进行直接电生理测量。长- 该部分的长期目标是评估是否监测 BrS 患者的血浆钠和钙水平 可能是预防 BrS 临床表现的有效方法。总而言之，该提案的结果 可能会为 BrS 的新诊断和治疗方法提供新的研究途径。所有建议的 实验将在弗吉尼亚理工大学的生物医学合作研究园区 FBRI 进行。随着 在她的赞助商和指导团队的支持下，该项目也将成为扩大和加强 研究员的技术和专业技能，以便为她作为职业规划的下一步做好准备 博士后助理正在成为心脏电生理学领域的独立研究员。