Anchored Kinase Signaling Mechanisms in Cardiac Hypertrophy

描述（由申请人提供）：心力衰竭是一种复杂的疾病，是西方世界死亡的主要原因。在美国，大约有500万人（占人口的2- 3%）患有这种疾病。增加的危险因素，如动脉高血压和瓣膜性心脏病，对心脏施加额外的生物力学压力，以诱导称为病理性心肌细胞肥大的细胞反应。这种情况的特征包括心肌细胞大小增加和肌节组织更大。在分子水平上，肥厚信号如升高的儿茶酚胺引起肌细胞增强因子（MEF2）通路的转录激活，从而改变蛋白质合成的模式。在过去的资助期间，我们已经开始破译一些蛋白质-蛋白质相互作用，这些相互作用有助于MEF2途径的空间和时间调节。我们已经确定了一种a激酶锚定蛋白，称为AKAP-Lbc，它协调启动MEF2介导的转录重编程事件的信号蛋白的激活和运动。我们的工作假设是，AKAP-Lbc同步蛋白激酶A （PKA）和蛋白激酶C （PKC）磷酸化事件，以促进第三种酶的激活，称为蛋白激酶D （PKD）。反过来，PKD磷酸化组蛋白去乙酰化酶HDAC5以促进其核输出。最后，核HDAC活性的降低有利于MEF2转录和心肌肥厚的发生。为了验证这一假设，提出了两个具体目标。

DESCRIPTION (provided by applicant): Heart failure is a complex disorder that is a leading cause of death in the Western world. Approximately 5 million people (2-3 % of the population) are afflicted with this disease in the United States. Increased risk factors such as arterial hypertension and valvular heart diseases place additional biomechanical stress on the heart to induce a cellular response known as pathological cardiomyocyte hypertrophy. Hallmarks of this condition include increased cardiomyocyte size and a greater organization of the sarcomere. At the molecular level, hypertrophic signals such as elevated catecholamines evoke transcriptional activation of the Myocyte Enhancer Factor (MEF2) pathway to change the pattern of protein synthesis. During the past funding period we have begun to decipher some of the protein-protein interactions that contribute to the spatial and temporal modulation of the MEF2 pathway. We have identified an A-Kinase Anchoring protein, called AKAP-Lbc that coordinates the activation and movement of the signaling proteins that initiate MEF2 mediated transcriptional reprogramming events. Our working hypothesis is that AKAP-Lbc synchronizes protein kinase A (PKA) and protein kinase C (PKC) phosphorylation events to facilitate activation of a third enzyme, called protein kinase D (PKD). In turn, PKD phosphorylates the histone deacetylase HDAC5 to promote its nuclear export. Finally, the concomitant reduction in nuclear HDAC activity favors MEF2 transcription and the onset of cardiac hypertrophy. Two specific aims are proposed to test this hypothesis. Specific aim 1: Does AKAP-Lbc organize transcriptional reprogramming? Our preliminary studies show that AKAP-Lbc supports PKD activation and favors nuclear export of HDAC5. Real-time fluorescent imaging will be used to establish if the anchoring protein organizes both signaling events in rat neonatal ventriculocytes (RNV). Related studies will measure MEF2 transcription upon disruption of protein-protein interactions between members of the AKAP/Lbc-PKD/HDAC pathway. Specific aim 2: Does the AKAP-Lbc/PKD/HDAC5 pathway contribute to heart disease? We propose that the AKAP-Lbc/PKD/HDAC5 pathway facilitates the onset of cardiac hypertrophy. Two complementary approaches will test this theory in vivo. Activation state antibodies will monitor the status of the AKAP-Lbc/PKD/HDAC pathway in normal and diseased human heart tissue. Analysis of knock in mice expressing a truncated AKAP-Lbc form that blocks PKD activation will determine if suppression of this signaling pathway protects against certain aspects of cardiac remodeling. Within the United States approximately 5 million people are afflicted with heart failure, a complex disorder that is a leading cause of death. Increased biomechanical stress on the heart induces a cellular response known as pathological cardiomyocyte hypertrophy. We have identified an A-Kinase Anchoring protein, called AKAP-Lbc that is up regulated in hypertrophic cardiomyocytes and that coordinates the activation and movement of signaling proteins upstream of MEF2-mediated transcriptional reprogramming events.