AGING AND G PROTEIN COUPLED RECEPTORS IN HUMAN HEART

心脏的正常功能涉及几个G蛋白偶联 受体，包括β-肾上腺素能，毒鼠碱，α-肾上腺素能， 内皮素和血管紧张素。因为心脏功能对我们来说 受年龄的影响，与年龄相关的年龄下降并不令人惊讶 心脏G蛋白偶联受体的反应性 有记录在案。然而，这些减少的分子基础仍然存在。 未知。在过去的十年里，相当数量的分子 关于通过G蛋白偶联受体传递信号的信息已经被 积攒起来的。具体地说，受体磷酸化已经成为一种主要的 GPCR信号转导中的因子。对β-肾上腺素能和 M受体表明这些受体经历了 被特定的激酶磷酸化，这一事件扰乱了受体/G 蛋白质偶联。由受体特异性蛋白(G蛋白)催化 受体激酶[GRK]同工酶)和第二信使激活的激酶 (蛋白激酶A和蛋白激酶C同工酶)，受体 磷酸化似乎是两者的潜在机制 同源(激动剂依赖)和异源(非激动剂非依赖) 脱敏。拟议的研究将通过以下方式描述这一机制 哪种衰老会导致心脏G的反应性降低 蛋白质偶联受体。这些研究将在心房上进行 从相对较年轻的(小于或等于55)获得的附件 年)和老年(大于或等于70岁)患者 心脏手术。我们的策略是首先确定分子 物种受年龄的影响，然后确定潜在的机制。 第一个具体目标将检验衰老改变 三种主要成分(受体/G蛋白/效应器)的表达 酶)通过心脏G蛋白参与信号转导- 偶联受体。第二个具体目标将检验这一假设 衰老减弱受体/G蛋白偶联；在这里，我们将研究 激动剂刺激掺入~(32)P标记的光亲和探针 叠氮苯胺基-GTP转化为受体相关的Galpha亚基。这种方法 以前没有被用来评估受体/G蛋白偶联 老化的心脏。第三个具体目标将检验衰老的假设 导致已知的蛋白激酶活性增加 磷酸化G蛋白偶联受体。私家侦探的广度 G蛋白偶联受体的生物化学研究及临床应用 PI实验室中各种试剂的可用性(GRK同工酶/G 蛋白质/抗体)将PI放置在一个独特的位置以成功 完成这些研究。

Normal functioning of the heart involves several G protein-coupled receptors, including beta-adrenergic, muscarinic, alpha1-adrenergic, endothelin, and angiotensin. Since cardiac performance is profoundly affected by age, it is not surprising that age-related decreases in the responsiveness of cardiac G protein-coupled receptors have been documented. The molecular bases of these decreases, however, remain unknown. Over the past decade, a considerable amount of molecular information on signaling through G protein-coupled receptors has been amassed. Specifically, receptor phosphorylation has emerged as a major factor in GPCR signaling. Extensive studies with beta-adrenergic and muscarinic receptors indicate that these receptors undergo phosphorylation by specific kinases, and this event disrupts receptor/G protein coupling. Catalyzed by receptor-specific kinases (G protein receptor kinase [GRK] isozymes) and second messenger-activated kinases (protein kinase A [PKA] and protein kinase C [PKC] isozymes), receptor phosphorylation appears to be the underlying mechanism for both homologous (agonist-dependent) and heterologous (agonist-independent) desensitization. The proposed studies will delineate the mechanism by which aging produces a decrease in the responsiveness of cardiac G protein-coupled receptors. These studies will be performed on atrial appendages obtained from relatively young (less than or equal to 55 years) and old (greater than or equal to 70 years) patients during cardiac surgery. Our strategy is to first identify the molecular species affected by age and to then determine the underlying mechanism. The first specific aim will test the hypothesis that aging changes the expression of the three main components (receptors/G proteins/effector enzymes) involved in signal transduction through cardiac G protein- coupled receptors. The second specific aim will test the hypothesis that aging diminishes receptor/G protein coupling; here we will examine agonist-stimulated incorporation of 32P-labeled photoaffinity probe azidoanilido-GTP into receptor-associated Galpha-subunits. This approach has not previously been used to assess receptor/G protein coupling in aged heart. The third specific aim will test the hypothesis that aging causes an increase in the activity of protein kinases known to phosphorylate G protein-coupled receptors. The PI's extensive experience in the biochemistry of G protein-coupled receptors and the availability of various reagents in the PI's laboratory (GRK isozymes/G proteins/antibodies) place the PI in a unique position to successfully complete these studies.