Engineered BacNav and BacCav for Improved Excitability and Contraction

受损的心肌细胞兴奋性和收缩功能是预防心肌缺血的重要靶点。 心源性猝死的发生和心力衰竭的进展。不断增长的机械理解 心脏病和越来越安全和有效的方法，以提供病毒到人体使基因 治疗是对抗各种心脏病的有吸引力的策略。具体来说，在基因上， 稳定方式，直接增加心肌细胞钠或L型钙电流，可直接增强细胞内钙离子浓度， 兴奋性和收缩性，并抵消各种心脏疾病中电异常的发生。 然而，心脏Na+或L-型Ca 2+通道基因太大而不能通过治疗性药物有效递送。 病毒，包括腺相关病毒（AAV）载体。为了应对这一挑战，我们建议制定一项 利用更小的原核电压门控钠的工程化的新的基于AAV的疗法 （BacNav）和钙（BacCav）通道基因。我们的初步结果表明，基因工程BacNav 在体外和计算机模拟模型中，通道可改善心肌细胞兴奋性和动作电位传导 大鼠和人类纤维化心脏组织。此外，我们证明了成功的心肌细胞特异性AAV 9 BacNav通道在健康鼠心脏中的递送对心脏电生理没有任何不利影响 或收缩功能。基于这些有希望的结果，我们提出：1）鉴定工程化BacNav变体 具有使心肌细胞兴奋性和动作电位速度最大化的特定突变和运输基序 通过利用体外细胞培养、离体心脏切片制备和计算机模拟，以及2）设计新的 BacCav的变体，其单独或与BacNav组合不仅可以增加心肌细胞的兴奋性， 还包括收缩强度，这将在体外使用工程化的3D心脏组织模型进行研究。最后我们 将利用受损的心脏组织兴奋性（心脏Na+电流（SCN 5A +/-）的遗传损失）的鼠模型 ））或收缩功能障碍（心肌梗死），以探索所鉴定的BacNav和BacCav基因中 通过AAV载体递送的药物将在体内诱导最佳的长期治疗效果。如果成功，这些研究将 为进一步研究哺乳动物原核细胞通道的调控机制奠定了基础 并将指导大型动物中工程化BacNav和BacCav通道疗法的测试 心脏病的模型

Impaired cardiomyocyte excitability and contractile function represent important targets for preventing the occurrence of sudden cardiac death and progression of heart failure. Growing mechanistic understanding of cardiac pathologies and increasingly safe and effective methods to deliver viruses to human body make gene therapies an attractive strategy for combatting various heart diseases. Specifically, the ability to genetically, in a stable fashion, directly augment sodium or L-type calcium current in cardiomyocytes could directly enhance cell excitability and contractility and counteract occurrence of electrical abnormalities in a variety of heart diseases. However, cardiac Na+ or L-type Ca2+ channel genes are too large to be effectively delivered by therapeutic viruses including adeno-associated viral (AAV) vectors. To address this challenge, we propose to develop a novel AAV-based therapy that leverages engineering of much smaller prokaryotic voltage-gated sodium (BacNav) and calcium (BacCav) channel genes. Our preliminary results show that genetically engineered BacNav channels can improve cardiomyocyte excitability and action potential conduction in in vitro and in silico models of rat and human fibrotic heart tissues. Furthermore, we demonstrate successful cardiomyocyte-specific AAV9 delivery of BacNav channels in healthy murine hearts without any adverse effects on cardiac electrophysiology or contractile function. Building on these promising results, we propose to: 1) identify engineered BacNav variants with specific mutations and trafficking motifs that maximize cardiomyocyte excitability and action potential speed by utilizing in vitro cell culture, ex vivo heart slice preparations, and computer simulations and 2) engineer new variants of BacCav, which alone or in combination with BacNav can augment not only cardiomyocyte excitability but also contractile strength, which will be studied using engineered 3D heart tissue models in vitro. Finally, we will exploit murine models of impaired cardiac tissue excitability (genetic loss of cardiac Na+ current (SCN5A+/- )) or contractile dysfunction (myocardial infarction) to explore which of the identified BacNav and BacCav genes delivered by AAV vector will induce optimal long-term therapeutic effects in vivo. If successful, these studies will create a foundation for the future mechanistic studies of prokaryotic channel regulation in mammalian cardiomyocytes and will guide testing of the engineered BacNav and BacCav channel therapies in large animal models of heart disease.