Dissecting GRK Function in the Heart

越来越清楚的是，G蛋白偶联受体(GPCR)激酶(GRKs)发挥着关键作用 在调节心肌信号和功能方面。GRKs磷酸化激动剂占据的GPCRs触发 脱敏的过程，导致下行信号的丢失。关于GPCRs的GRK行动 促进B-arrestin与受体结合，从而导致受体内化和再增敏 因为新信号的激活是级联的。正如在本PPG的第一个供资周期中所描绘的那样，GRK 而B-拦截素似乎通过下游的信号系统在心脏中具有新的作用。 不敏感的GPCRs。GRK2是心肌中表达最丰富的GRK亚型，通过我们的 在过去的15年里，我们与Rockman博士和Lefkowitz博士密切合作，发现了一个明确的 GRK2通过对p-肾上腺素能受体(PAR)信号的调控在衰竭心脏中的重要性。 我们在这个PPG中的最新数据已经阐明了GRK2可能对心脏信号和 功能不仅通过调节bar介导的收缩功能，而且通过独特的细胞 靶点，包括改变慢性心力衰竭(HF)进展的细胞生存途径。与此一致的是， 这项提案中将提供数据，证明GRK2可以增加心肌细胞在 缺血性损伤。此外，我们提供的数据表明，GRK2存在于线粒体中，并具有独特的 与一氧化氮合酶(NOS)、一氧化氮(NO)的关系这包括与 这个PPG组的成员第一次展示了GRK2可以被S亚硝化。看起来不是 生物利用度调节GRK2对棒材的S活性。因此，通过新的蛋白质-蛋白质相互作用或 通过独特的细胞定位和调节，GRK2似乎具有对正常至关重要的多种功能 心脏应激时的心功能和适应，特别是可导致心衰的缺血损伤。在这 项目中，将探索GRK2在心脏中的新方面，这是相互关联的，并由 其他项目集中在心肌细胞PAR信号、其受其他GRK和B-arrestin功能的调节以及 监管。这个项目也将得到这个PPG中的科学核心的极大帮助。我们的中环 假设GRK2在心脏的信号和生理中起着重要的作用 对于受损和受损的心肌，尤其是在缺血后，情况危急。这包括Padreneric以外的影响 依赖的收缩功能，涉及新的GRK调节、细胞定位和下游 目标。具体目的是：(1)确定GRK2在病理生理学中的作用机制 包括心肌细胞存活在内的心肌缺血性损伤；(2)探讨GRK2- 一氧化氮合酶(NOS)与心脏中NO的联系和机制关系；以及(3)确定 S亚硝化的生理作用及其对心脏GRK2及其活性的调节

It is becoming increasingly clear that G protein-coupled receptor (GPCR) kinases (GRKs) play a critical role in modulating myocardial signaling and function. GRKs phosphorylate agonist-occupied GPCRs triggering the process of desensitization, leading to the loss of down-stream signaling. GRK action on GPCRs promotes B-arrestin binding to receptors, which leads to receptor internalization and resensitization as well as activation of novel signaling cascades. As delineated during the first funding cycle of this PPG, GRKs and B-arrestins appear to have novel actions in the heart through signaling systems that are down-stream of desensitized GPCRs. GRK2 is the most abundant GRK isoform expressed in myocardium and through our close collaboration with Drs. Rockman and Lefkowitz over the last 15 years, we have uncovered a clear importance of GRK2 in the failing heart via its regulatory control on p-adrenergic receptor (PAR) signaling. Recent data by us within this PPG has elucidated that GRK2 may have influences on cardiac signaling and function not only through regulation of BAR-mediated contractile function but also through unique cellular targets, including cell survival pathways altering progression of chronic heart failure (HF). Consistent with this, data will be presented in this proposal demonstrating that GRK2 can increase myocardial apoptosis after ischemic injury. Moreover, we present data showing that GRK2 is present in mitochondria and has a unique relationship with nitric oxide synthase (NOS) and nitric oxide (NO). This includes the collaborative finding with members of this PPG group showing, for the first time, that GRK2 can be S-nitrosylated. It appears that NO bioavailability regulates GRK2's activity towards BARs. Therefore, through novel protein-protein interactions or through unique cellular localization and regulation, GRK2 appears to have multi-functions critical for normal cardiac function and adaptation during cardiac stress, especially ischemic injury, which can lead to HF. In this Project, novel aspects of GRK2 in the heart will be explored, which is inter-related and complemented by the other projects focused on myocyte PAR signaling, its regulation by other GRKs and B-arrestin function and regulation. This Project will also be greatly aided by the scientific Cores within this PPG. Our Central Hypothesis is that GRK2 plays important roles in the signaling and physiology of the heart that becomes critical in injured and compromised myocardium, especially after ischemia. This includes effects beyond padrenergic dependent contractile function and involves novel GRK regulation, cellular localization and downstream targets. The Specific Aims are: (1) To determine the mechanistic role of GRK2 in the pathophysiology of myocardial ischemic injury including myocyte survival; (2) To investigate the in vivo significance of a GRK2 - nitric oxide synthase (NOS) and NO linkage and mechanistic relationship in the heart; and (3) To determine the physiological role of S-nitrosylation and its regulation of GRK2 and its activity in the heart.