Regulation Of Ischemic Preconditioning By Compartmentalized Signal Transduction

描述(由申请者提供)：心脏病是美国发病率和死亡率的主要原因。了解该病的病因和开发治疗方法是生物医学研究的重要目标。虽然缺氧会对心脏组织造成损害，但通过短暂的缺血-再灌流可以保护心肌。虽然这种现象涉及磷脂酰肌醇-3‘-激酶通路(PI3K)的激活，但PI3K在这一反应中的分子调控尚未很好地确定。在这项研究中，我们希望通过对PI3K家族的调节来确定交叉素(ITSN)支架蛋白在调控心肌组织对缺血再灌注(IR)损伤反应中的作用。我们已经确定PI3Ks是ITSN结合蛋白，并将确定ITSN在心肌细胞和新的小鼠模型中调节PI3Ks的作用，包括心脏特异的ITSN转基因小鼠(MHC-ITSN)和ITSN基因敲除小鼠。我们提出以下四个具体目标来确定ITSN调节心肌缺血损伤保护的分子机制：(1)确定ITSN在调节心肌细胞PI3K激活中的作用；(2)确定ITSN调节PI3K激活的机制；(3)确定ITSN-PI3K发出的下游信号；以及(4)确定ITSN在介导在体IR损伤所致心肌保护中的重要性。这些针对特定AIMS 1-3的实验将在体外模型中确定ITSN对G蛋白偶联受体和受体酪氨酸激酶激活反应的各种PI3K家族成员的分子调控以及这种激活所产生的下游信号。在具体目标4中，这些结果将应用于我们创建的新型小鼠模型的研究。MHC-ITSN小鼠将研究ITSN过度表达对IR损伤的心脏保护的后果，而基因敲除小鼠将研究ITSN丢失对IR损伤反应的后果。这些数据将为ITSN对心脏组织中PI3K蛋白家族的调控提供新的分子洞察力，并将确定这一调控在心脏保护和心脏功能中的重要性。公共卫生相关性：心肌梗死给美国医疗保健系统带来了巨大的负担。我们提出的研究将定义保护心脏免受缺血损伤的新的分子途径。考虑到这些通路也在包括大脑在内的许多组织中共享，这些研究也可能为限制中风的有害影响提供新的见解。

DESCRIPTION (provided by applicant): Heart disease represents a leading cause of morbidity and mortality in the US. Understanding the causes and developing treatments for this disease is an important goal of biomedical research. Although oxygen deprivation results in damage to cardiac tissue, it is possible to protect the myocardium by brief periods of ischemia-reperfusion. Although this phenomenon involves activation of the phosphatidylinositol-3' kinase pathway (PI3K), the molecular regulation of PI3Ks during this response has not been well defined. In this proposal, we wish to determine the role of the intersectin (ITSN) scaffold protein in regulating the response of cardiac tissue to ischemia-reperfusion (IR) injury through regulation of the PI3K family. We have identified PI3Ks as ITSN-binding proteins and will determine the role of ITSN in regulating PI3Ks both in myocardial cells and in novel mouse models including a cardiac-specific ITSN transgenic mouse (MHC-ITSN) and an ITSN knockout mouse. We propose the following four specific aims to define the molecular mechanisms by which ITSN regulates cardioprotection from ischemic injury: (1) determine the role of ITSN in regulating PI3K activation in cardiomyocytes; (2) determine the mechanism by which ITSN regulates PI3K activation; (3) determine the downstream signals emanating from ITSN-PI3K; and (4) determine the importance of ITSN in mediating cardioprotection in response to IR injury in vivo. The experiments proposed for Specific Aims 1-3 will define the molecular regulation of the various PI3K family members by ITSN in response to G-protein coupled receptor and receptor tyrosine kinase activation and the downstream signals resulting from this activation in in vitro models. In Specific Aim 4, these results will be applied to the study of the novel mouse models created by us. The MHC-ITSN mice will address the consequence of ITSN overexpression on cardioprotection from IR injury whereas the knockout mice will address the consequences of ITSN loss on the response to IR injury. These data will provide novel molecular insight into the regulation of the PI3K family of proteins by ITSN in cardiac tissue and will define the importance of this regulation in cardioprotection and cardiac function. PUBLIC HEALTH RELEVANCE: Myocardial infarction results in a significant burden to the US healthcare system. Our proposed studies will define novel molecular pathways involved in protecting the heart from ischemic injury. Given that these pathways are also shared among many tissues including the brain, these studies may also provide novel insights into limiting the harmful effects from stroke.