Role of Sphingolipids in Cardiac Ischemia

描述(由申请人提供)：急性心脏缺血，如心肌梗塞(MI)，是美国主要的死亡原因之一。到目前为止，还没有FDA批准的药物可以通过直接干扰细胞死亡过程来缩小梗塞面积或防止进展为心肌梗死。大多数治疗包括内科治疗(如TPA)或程序性治疗(如血管成形术)，旨在对缺血心肌进行再灌流。有证据表明，细胞死亡过程中的一个非常早期的事件涉及鞘磷脂信号分子的激活，这种信号分子对心脏细胞有很大的损害。这项SBIR第一阶段和第二阶段的拟议工作的目标是证明中性形式的神经鞘磷脂酶(NSMase)及其接头蛋白FAN(与中性神经鞘磷脂酶激活相关的因子)是心肌缺血患者心脏保护治疗的有效靶点。这些信号成分位于死亡过程中MAP激酶、半胱氨酸天冬氨酸酶和原癌基因的上游。除了验证靶点外，我们还打算阐明关键的鞘磷脂信号分子在产生与急性心肌缺血相关的负性肌力和细胞死亡方面的作用机制。在这项工作的第一阶段，我们打算在缺乏神经鞘磷脂信号系统的这些重要组成部分的FAN和nSMase基因敲除小鼠中，通过外科手术造成可逆性心肌梗死。在这种缺血/再灌注(IR)损伤模型中，如果KO小鼠的Fan/nSMase信号系统与对照组相比不起作用，预计梗死面积占危险区域的百分比将会减少。这些方法将与我们的IR损伤的心肌细胞培养模型一起使用，提供额外的原理证明，即FAN/SMASE信号系统是急性心肌缺血的关键原因

DESCRIPTION (provided by applicant): Acute cardiac ischemia such as myocardial infarction (MI) is one of the leading causes of death in the US. To date, there are no FDA-approved drugs that reduce the size of the infarct or prevent the progression to MI by directly interfering with the cell death process. Most treatments involve either medical (e.g., TPA) or procedural (e.g., angioplasty) treatments intended to reperfuse the ischemic myocardium. Evidence suggets that a very early event in the cell death process involves activation of sphingolipid signaling molecules that are largely damaging to cardiac cells. It is the goal of the proposed work in both Phase I and Phase II of this SBIR is to prove the principle that the neutral form of sphingomyelinase (nSMase) and its adaptor protein, FAN (factor associated with neutral SMase activation), are valid targets for cardioprotective therapy in patients with myocardial ischemia.These signaling components are up-stream of the MAP kinases, caspases and proto-onogenes of the death process. In addition to validating the targets, we intend to elucidate the mechanisms of action of key sphingolipid signaling molecules in producing the negative inotropy and cell death associated with acute cardiac ischemia. In Phase I of the work, we intend to surgically produce reversible cardiac infarcts in FAN and nSMase knockout mice lacking these important components of the sphingolipid signaling system. In this model of ischemia/reperfusion (IR) injury, infarct sizes as a percentage of areas of risk are expected to be reduced if the FAN/nSMase signaling system is non-functional in the KO mouse compared to control litermates. These methods will be used in conjunction with our cardiomyocyte cell culture model of IR injury provide additional proof-of-principle that the FAN/SMase signaling system is key causal factor in acute cardiac ischemia