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.

项目摘要 Brugada综合征是一种罕见但严重的疾病，可导致心律失常和心脏性猝死。 没有结构性心脏病的儿童和年轻人。导致这种疾病的最显著的基因因素 是编码电压门控钠通道NaV1.5的基因SCN5A的功能突变。然而， 许多具有这些突变的BRS患者在经历重大心律失常事件之前是没有症状的，使 这种综合症在自然界中是“隐蔽的”。虽然诊断药物的挑战存在于那些有高风险成为 有症状，阳性预测值低。NaV1.5的损耗与电导的关系 减慢，心律失常是公认的，有可能是隐匿性传导减慢是 BRS病理的潜在驱动因素。本提案旨在利用BRS的SCN5A杂合子小鼠模型 确定在完整心脏内调节触觉耦合是否可以揭示BRS相关 传导减慢。在目标1中，触觉耦合将通过改变周围神经节的宽度来操纵，一个 在朗宁多夫灌流的SCN5A+/-和WT小鼠心脏中，插入盘的纳米结构域。 传导速度将使用光学标测来评估，其中完整的心脏被注入电压 敏感的染料，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。到时候她会的 使用这项技术来确认会宽度的变化。该组件的长期目标是开发 一种新的BRS诊断方法。这项提案的目标2将调查低钠血症是否可以揭示更大的 相对于WT，Sn5a+/-小鼠心脏的传导减慢。再说一次，这个家伙将利用光学 测绘以评估传导以响应这一变化。她最近与马特博士的实验室合作 Kay在乔治华盛顿大学学习如何建立和实施浮动微电极，并将 继续与这个小组合作，以便在波尔津博士在Fralin Biomedical的实验室建立这项技术 弗吉尼亚理工大学卡里昂研究所(FBRI)。浮动微电极技术将提供稳定和 直接从完整的、跳动的小鼠心脏对低钠血症做出反应的电生理测量。长的- 该部分的长期目标是评估是否监测BRS患者的血钠和钙水平 可能是预防BRS临床表现的有效方法。总之，这项提议的结果是 可能为BRS的新诊断和治疗提供新的研究途径。所有建议的 实验将在弗吉尼亚理工大学的合作生物医学研究园区FBRI进行。与 在她的赞助商和指导团队的支持下，这个项目也将成为扩大和加强 Follow的技术和专业技能，以便为她职业生涯规划的下一步做好准备 博士后助理，即将成为心脏电生理学领域的独立研究员。