Unfolded Protein Response and Arrhythmias

项目摘要 改变的膜电流与心脏性猝死有关。缺血性心肌病（ICM）是 造成了四分之三的死亡在初步的数据，我们表明，（一）PERK，部分展开 蛋白质应答（UPR）在小鼠心肌梗死（MI）模型中被早期和持续激活，（ii） 心肌梗死后抑制PERK可减少猝死，减少自发性、非持续性室性心动过速 (VT)，缩短QTc间期，并缩短动作电位时程（APD），而不会产生不良后果， 收缩功能，（iii）UPR激活抑制APD，减慢AP上行，并改变部分但不是全部离子通道。 PERK抑制部分逆转APD延长和一些离子通道下调。 假设：我们假设PERK和其他UPR传感器的激活降低了mRNA丰度， 心脏离子通道的蛋白质翻译。这有助于电流改变、APD延长和 增加ICM的药物风险。PERK或其他UPR效应物的抑制可以防止一些 重塑在体内，PERK抑制将在ICM中具有抗心律失常作用，部分是通过改善传导速度， 降低APD。 具体目标： 目的1：确定PERK抑制可防止APD延长的程度，电刺激 与ICM相关的重塑和血管风险。为此，将在小鼠中诱导ICM。APD， 将在具有和不具有药理学作用的小鼠之间比较电重构和脑卒中风险。 在梗塞后立即或在3周开始抑制PERK，以测试预防与治疗策略。 将结果与PERK的遗传抑制（心脏特异性PERK敲除（KO））和结果进行比较。 在人类ICM中。 目的2：确定PERK在多大程度上可以促进APD延长和 离子通道使用人诱导多能干细胞衍生的心肌细胞（hiPSC-CM）， UPR，我们将确定哪些其他离子通道被UPR和PERK激活改变，并负责 APD延长。 目的3：研究UPR的IRE 1和ATF 6分支是否有助于APD延长 以及离子通道的改变。使用hiPSC-CM并激活HiPSC-CM的IRE 1和ATF 6 β分支， UPR，我们将确定这两个分支的激活是否有助于AP变化， 下调心脏离子通道。

Project Summary Altered membrane currents are implicated in sudden cardiac death. Ischemic cardiomyopathy (ICM) is responsible for three quarters of these deaths. In preliminary data, we show that (i) PERK, part of the unfolded protein response (UPR), is activated early and persistently in a mouse myocardial infarct (MI) model, (ii) inhibiting PERK after MI reduces sudden death, reduces spontaneous, nonsustained ventricular tachycardia (VT), reduces QTc interval, and reduces action potential duration (APD) without negative consequences to contractile function, (iii) the UPR activation prolongs APD, slows AP upstroke, and alters some but not all ion channels, and (iv) PERK inhibition partially reversed APD prolongation and some ion channel downregulations. Hypothesis: We hypothesize that activation of PERK and other UPR sensors reduce mRNA abundance and protein translation of cardiac ion channels. This contributes to current alterations, APD prolongation, and increased arrhythmic risk in ICM. Inhibition of PERK or other UPR effectors can prevent some of the remodeling. In vivo, PERK inhibition will be antiarrhythmic in ICM, in part, by improving conduction velocity and reducing APD. Specific aims: Aim 1: Determine the extent to which PERK inhibition can prevent APD prolongation, electrical remodeling and arrhythmic risk associated with ICM. In this aim, ICM will be induced in mice. APD, electrical remodeling and arrhythmic risk will be compared between mice with and without pharmacological inhibition of PERK starting immediate after infarct or at 3 weeks to test prevention versus treatment strategies. Results will be compared to genetic inhibition of PERK (cardiac specific PERK-knockout (KO)) and to findings in human ICM. Aim 2: Determine the extent to which PERK can contribute to APD prolongation and the alterations of ion channels. Using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) with activated UPR, we will determine which other ion channels are altered by UPR and PERK activation and are responsible for APD prolongation. Aim 3: Investigate whether the IRE1 and ATF6 branches of the UPR contribute to APD prolongation and the alterations of ion channels. Using hiPSC-CMs and activating the IRE1 and ATF6 branches of UPR, we will determine whether activation of these two branches contributes to AP changes and downregulation of cardiac ion channels.