DYRK1a as a therapeutic target to treat myocardial infarction

摘要 尽管心肌梗死 (MI) 后的结局有所改善，但即使使用 再灌注成功。这种损失会导致不良重塑、缺血性心肌病、心力衰竭、 心律失常和死亡。目前的疗法只能减缓或逆转缺血性心脏病的个别方面， 并且没有可靠的疗法可以替代因心肌梗死而导致的心肌损失。确定治疗方法 保护损伤后心肌的靶点和药物将具有开创性，解决未满足的临床需求， 并代表了治疗心血管疾病的新策略。我们的目标是识别和验证可成药的 诱导受控 CM 循环并改善损伤后心脏功能的目标。然而，存在两个挑战： (1) 确定刺激 CM 循环的候选途径，以改善心脏功能 损伤后，(2) 成人心肌中 CM 循环事件的准确量化。因此，我们 进行了调查以解决这两个挑战。首先，我们鉴定了一种双特异性酪氨酸抑制剂 磷酸化调节激酶 1a (DYRK1a)、Harmine、增加 CM 循环并改善心室 MI 后的功能。接下来，我们生成了 CM 特异性 DYRK1a 敲除小鼠并观察了 CM 增生 MI 后 LV 功能的基线和改善，表明 DYRK1a 有助于 CM 功能。第二，我们 设计并验证了一种独特的转基因小鼠（表示为 αDKRC），该小鼠可在成人自行车运动中驱动 Cre CM。 αDKRC 补充了双标记马赛克分析 (MADM) 等现有技术； 然而，将 Cre 表达限制在成体循环 CM 上的能力是该领域的一项进步。我们 使用 αDKRC::DTA 小鼠在成年循环 CM 中表达白喉毒素，并观察到 MI 后，内源性循环 CM 使心肌功能恶化。由于自行车 CM 稀缺，研究结果 表明循环 CM 可能对心肌功能的贡献超出了 CM 仅作为收缩性药物的概念 细胞，可能是通过表达旁分泌因子。这种潜在的机制表明，适度增加 循环 CM 可能对 MI 后的心功能产生更显着的影响，因为循环 CM 可以发挥作用 功能超出了收缩性的概念。根据初步数据，我们假设抑制 DYRK1a 部分通过增强 CM 循环和循环 CM 发挥作用，改善 MI 后的心肌功能 它们通过旁分泌因子产生影响。我们将在以下目标中检验我们的假设：（1）CM 特异性消融 DYRK1a 在发育过程中通过增强细胞循环来保护 MI 后的左心室功能，(2) 成人 CM 中 DYRK1a 的发育性消融将改善 MI 后的左心室功能，并且 (3) 循环 CM 有助于 通过表达旁分泌因子来影响 MI 后的 LV 功能。拟议的调查将确定潜力 DYRK1a 抑制作为 MI 的治疗方法，确定 DYRK1a 在 MI 中发挥作用的机制 CM，并表征了循环 CM 表达的新型旁分泌因子，这些因子可能成为新的未来 治疗目标。

ABSTRACT Although outcomes after myocardial infarctions (MIs) have improved, cardiomyocytes (CMs) are lost even with successful reperfusion. This loss contributes to adverse remodeling, ischemic cardiomyopathy, heart failure, arrhythmia, and death. Current therapies can only slow or reverse isolated aspects of ischemic heart disease, and there are no reliable therapies available to replace the cardiac muscle loss to MI. Identifying therapeutic targets and drugs to protect the myocardium after injury will be groundbreaking, address unmet clinical needs, and represent new strategies to treat cardiovascular diseases. Our goals are to identify and validate druggable targets that induce controlled CM cycling and improve heart function after injury. However, two challenges exist: (1) the identification of candidate pathways to stimulate CM cycling with the intent to improve cardiac function after injury, and (2) the accurate quantification of CM cycling events in adult myocardium. Therefore, we conducted investigations to address the two challenges. First, we identified an inhibitor of dual-specificity tyrosine phosphorylation-regulated kinase 1a (DYRK1a), Harmine, increased CM cycling, and improved ventricular function after MI. Next, we generated CM-specific DYRK1a knockout mice and observed CM hyperplasia at baseline and improved LV function after MI, suggesting DYRK1a contributes to CM function. Second, we designed and validated a unique transgenic mouse (denoted αDKRC) that drives Cre in adult cycling CMs. αDKRC complements existing technologies such as Mosaic Analysis with Double Markers (MADM); however, the ability to restrict Cre expression to adult cycling CMs is an advance in the field. We used αDKRC::DTA mice to express Diphtheria toxin in adult cycling CMs and observed that the loss of endogenously cycling CMs worsened myocardial function after MI. Since cycling CMs are scarce, the findings suggest that cycling CMs may contribute to myocardial function beyond the concept of a CM as only a contractile cell, perhaps by expressing paracrine factors. This potential mechanism suggests that modest increases in cycling CMs may have a more significant impact on cardiac function after MI because cycling CMs serve functions beyond the concept of contractility. Based on preliminary data, we hypothesize that the inhibition of DYRK1a improves myocardial function after MI, in part, through enhanced CM cycling and the cycling CMs exert their effects via paracrine factors. We will test our hypothesis in the following Aims: (1) The CM-specific ablation of DYRK1a during development protects LV function after MI through enhanced cell cycling, (2) The post- developmental ablation of DYRK1a in adult CMs will improve LV function after MI, and (3) Cycling CMs contribute to LV function after MI by expressing paracrine factors. The proposed investigations will define the potential of DYRK1a inhibition as a treatment of MI, identify the mechanisms through which DYRK1a exerts its effects in CMs, and characterize novel paracrine factors expressed by cycling CMs that potentially serve as new future therapeutic targets.