Alpha1-Adrenoceptor Subtype Signaling in Preconditioning

描述(由申请人提供)：心肌预适应(PC)保护心脏免受缺血性心脏病和缺血-再灌注损伤的后果。缺血时释放的儿茶酚胺通过激活心脏中的α1肾上腺素受体(AR)诱导心肌PC。心脏表达两种α1-AR亚型。最近，在α1-AR亚型基因敲除(KO)小鼠中，发现每个α1-AR亚型激活不同的信号通路。该项目的主要目标是确定导致儿茶酚胺诱发PC的亚型(S)，PC的诱发机制，以及最终是否可以利用治疗学来利用亚型特异性信号来促进心脏健康。α1-AR亚型(S)负责儿茶酚胺诱导的早期和晚期PC，将在功能丧失研究中使用α1-AR亚型KO小鼠来确定。在体小鼠缺血型PC模型将被用来研究α1-AR和缺血型PC对梗塞面积的影响。采用体外小鼠朗宁多夫心脏模型，研究α1-AR和缺血诱导的PC对心肌顿抑的影响。亚型特异性信号级联研究将集中在通过PI3K/AKT、活性氧、蛋白激酶C、丝裂原活化蛋白激酶和酪氨酸激酶激活的预适应过程中的抗凋亡信号。在免疫沉淀实验中，将使用标记的Alpha1A和Alpha1B亚型来研究在每个亚型上形成的能够解释亚型信号差异的信号复合体。晚期PC需要基因转录。我们已经确定了几个可能参与晚期PC的候选基因。将研究基因表达的调节以及这些基因产物如何对PC做出贡献。心脏长时间预适应的能力将是许多临床应用的重要贡献，这些临床应用包括：心脏在长时间的缺血性心脏病或缺血再灌注损伤期间暴露于或处于危险之中。过度表达和增强与PC有关的α1-AR亚型特异性信号的益处将通过基因治疗方法进行测试。该亚型将使用腺病毒载体在心脏中迅速表达。

DESCRIPTION (provided by applicant): Myocardial preconditioning (PC) protects the heart from the consequences of ischemic heart disease and ischemia - reperfusion injury. Catecholamines released during ischemia induce myocardial PC by activating alpha1-adrenoceptors(AR) in the heart. Two alpha1-AR subtypes are expressed in the heart. Recently, in alpha1-AR subtype knockout (KO) mice, each alpha1-AR subtype was found to activate different:signaling pathways. The broad objective of this project is to define the subtype(s) that are responsible for catecholamine induced PC, the mechanisms by which PC is induced, and ultimately whether therapeutics can be utilized to capitalize on subtype specific signaling to benefit cardiac health. The alpha1-AR subtype(s) responsible for catecholamine induced early and late PC will be determined using alpha1-AR subtype KO mice in loss of function studies. An in vivo mouse model of ischemic PC will be used to study the effect of alpha1-AR- and ischemia- induced PC on infarct size. An in vitro mouse Langendorf heart model will be used to study the effect of alpha1-AR- and ischemia- induced PC on myocardial stunning. Subtype specific signaling cascade studies will focus on antiapoptotic signaling via PI3K/AKT, reactive oxygen species, protein kinase C, mitogen activated protein kinases, and tyrosine kinase activation during preconditioning protocols. Signaling complexes formed at each subtype that can account for differences in subtype signaling will be studied using tagged alpha1A and alpha1B subtypes in immunoprecipitation experiments. Late PC requires gene transcription. We have identified several candidate genes that may participate in late PC. The regulation of gene expression and how these gene products contribute to PC will be studied. The ability to precondition the heart for prolonged periods would be an important contribution to many clinical applications where:the heart is exposed to or at risk during prolonged ischemic heart disease or with ischemia - reperfusion injury. The benefits of overexpressing and enhancing alpha1-AR subtype-specific signaling responsible for PC will be tested using a gene therapy approach. The subtype will be expressed in the heart acutely using an adenovirus vector.