DYRK1a as a therapeutic target to treat myocardial infarction

摘要 尽管心肌梗死(Mis)后的预后有所改善，但心肌细胞(Cms)即使在 再灌流成功。这种缺失会导致不良重塑、缺血性心肌病、心力衰竭、 心律不齐和死亡。目前的治疗方法只能减缓或逆转缺血性心脏病的孤立方面， 而且目前还没有可靠的治疗方法来弥补心肌梗死造成的心肌损失。确定治疗方法 损伤后保护心肌的目标和药物将是开创性的，解决未满足的临床需求， 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用药 诱导受控的CM循环和改善损伤后心功能的靶点。然而，存在两个挑战： (1)确定刺激CM骑自行车以改善心脏功能的候选途径 (2)成年心肌CM循环事件的准确定量。因此，我们 进行了调查，以应对这两个挑战。首先，我们确定了一种双特异性酪氨酸的抑制剂。 磷酸化调节的激酶1a(DYRK1a)，三尖杉酯碱，增加CM循环，改善心室 MI后的功能。接下来，我们建立了CM特异的DYRK1a基因敲除小鼠，并观察到CM在 心肌梗死后基础状态和左心功能改善，提示DYRK1a参与心肌功能。第二，我们 设计并验证了一种独特的转基因小鼠(标记为αDKRC)，它在成年自行车运动中驱动CRE 不育系CMS。αDKRC是对现有技术的补充，如双标记镶嵌分析； 然而，将Cre的表达限制在成年自行车CMS的能力是该领域的一项进步。我们 用αdkrc：：dta小鼠在成年骑行不育系中表达白喉毒素，观察白喉毒素在成年骑行不育系中的丢失 内源性循环CMS使心肌梗死后心功能恶化。由于骑自行车的CMS很少，所以研究结果 提示循环CMS可能对心肌功能有贡献，而不仅仅是作为一种收缩 细胞，可能是通过表达旁分泌因子。这一潜在的机制表明， 循环CMS可能对心梗后的心功能有更显著的影响，因为循环CMS 其功能超越了可伸缩性的概念。根据初步数据，我们假设抑制作用 DYRK1a改善心肌梗死后心肌功能的作用部分是通过增强CM循环和循环CMS而实现的 它们通过旁分泌因子发挥作用。我们将在以下目标中验证我们的假设：(1)CM特定消融 DYRK1a在发育过程中通过增强细胞周期保护心肌梗死后的左心功能，(2)后 成年CMS中DYRK1a的发育消融将改善MI后的左心功能，(3)骑行CMS对此有贡献 通过表达旁分泌因子实现心肌梗死后的左心功能。拟议的调查将确定 DYRK1a抑制治疗心肌梗死，明确DYRK1a发挥作用的机制 CMS，并表征了循环CMS表达的新的旁分泌因子，这些新的旁分泌因子可能是新的未来 治疗靶点。

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.