BETA1 AND BETA2 ADRENOCEPTOR SIGNALING IN CARDIAC MYOCYTE

描述（由申请人提供）：β肾上腺素受体（β ARs）信号被精细调节，以控制心血管功能，以响应交感神经系统输入（去甲肾上腺素）和肾上腺素（肾上腺素）。在动物心脏中，儿茶酚胺刺激两种高度同源的β AR （1 β AR和2 β AR）以增强收缩力和心率。循环儿茶酚胺升高对心脏β AR的慢性刺激以及心脏β AR密度的降低在临床上与心力衰竭有关。gpcr的主要功能是配体结合和g蛋白偶联。然而，GPCRs在体内的特异性和多样化的功能特性涉及到信号复合物中结合不同伴侣的动态受体构象变化，以及受体信号复合物以细胞类型特异性的方式定位。我们假设去甲肾上腺素和肾上腺素可以激活心肌细胞中不同的1 β AR和2 β AR信号通路。我们选择从β AR基因缺陷小鼠分离的新生儿心肌细胞作为模型系统，研究配体-受体相互作用在分化细胞中的功能作用。本研究的目的是：(1)表征新生儿肌细胞中不同激动剂对1 β AR和2 β AR亚型特异性信号传导的影响；(2)确定心肌细胞中1 β AR和2 β AR在去甲肾上腺素和肾上腺素刺激下的细胞生化特性；(3)表征心肌细胞中1 β AR和2 β AR及其他信号分子在去甲肾上腺素和肾上腺素刺激下的亚细胞分布。(4)鉴定受体相互作用域及其靶蛋白，表征受体信号复合物在激动剂刺激下的形成和稳定性。更好地了解激动剂诱导的AR构象变化对信号复合物组织的影响可能有助于新药设计，并为治疗各种心血管疾病提供新的临床应用。

DESCRIPTION (provided by applicant): Beta Adrenoceptors (Beta ARs) signaling is finely regulated to control cardiovascular function in response to sympathetic nervous system input (norepinephrine) and to adrenaline (epinephrine) from the adrenal gland. In animal hearts, two highly homologous Beta ARs (1Beta AR and 2Beta AR) are stimulated by catecholamines to enhance contractility and heart rate. Chronic stimulation of cardiac Beta ARs by elevated circulating catecholamines as well as decreased cardiac 1Beta AR density is clinically associated with heart failure. The primary functions attributed to GPCRs are ligand binding and G-protein coupling. However, the specific and diversified functional properties of GPCRs in vivo involve kinetic receptor conformational changes for binding different partners in signaling complexes, and the localization of receptor signaling complexes in cell type- specific manner. We hypothesize that norepinephrine and epinephrine can activate distinct signaling pathways for both 1Beta AR and 2Beta AR in cardiac myocytes. We have chosen the neonatal cardiac myocyte isolated from the Beta AR gene deficienct mice as a model system to study the functional roles of ligand- receptor interactions in differentiated cells. The goals of this proposal are (1) to characterize 1Beta AR and 2 Beta AR subtype-specific signaling by different agonists in neonatal myocytes, (2) define the cellular and biochemical properties of 1Beta AR and 2Beta AR under norepinephrine and epinephrine stimulation in cardiac myocytes, (3) to characterize the subcellular distribution of 1Beta AR and 2Beta AR, and other signaling molecules under norepinephrine and epinephrine stimulation in cardiac myocytes, (4) to identify receptor interaction domains and their targeted proteins, and to characterize the receptor signaling complex formation and stability upon agonist stimulation. A better understanding of agonist-induced AR conformation change for the organization of signaling complexes may facilitate new drug designs and suggest new clinical applications in treating various cardiovascular diseases.