Hormonal Regulation of Phosphodiestrases

描述(由申请人提供)：通过这项提议，我们打算检验4型环核苷酸磷酸二酯酶(PDE4)对cAMP动态平衡和受体信号特异性至关重要的总体假设。有充分的药理学证据表明，PDE4有助于肾上腺素能、前列腺素和促性腺激素受体产生的cAMP信号的形成。然而，单个PDE4亚型在细胞中的功能在很大程度上是未知的。四个PDE4基因和二十多个剪接变异体的存在，引发了这样一个复杂性的功能意义的问题。我们认为，不同的PDE4变体在大分子复合体中发挥作用，以指定控制大多数生物过程的信号，包括心肌细胞中的兴奋/收缩偶联。这些复合体有助于与肾上腺素能受体1和2相关的不同的生物学反应。事实上，我们对PDE4KO表型的分析已经提供了PDE4D和PDE4B在体内发挥不同功能的初步证据。PDE4D消融后并发心律失常和心力衰竭的迟发性心肌病意味着切除单个PDE4会导致微小但严重的心脏功能丧失。这项建议的目的是了解这些缺陷的性质和后果，因为它们将提供更好的了解cAMP信号通路的特性，并预测针对该信号通路的药物干预的结果。遗传和生化方法将被用来理解PDE4与肾上腺素能受体1和2的相互作用。该实验计划是按照三个具体目标制定的。第一个目的是探讨PDE4D激活在肾上腺素能信号转导中的作用及其功能。第二个具体目标将致力于分析AR/PDE4复合体及其在受体功能中的作用。最后一个具体目的是探讨破坏这些复合体对体外和体内心肌细胞功能的影响。除了揭示交感神经对心脏功能的调节外，这些研究还将为以PDE和cAMP信号为靶点的新的治疗策略提供合理的基础。 公共卫生相关性：拟议的实验将阐明对心脏功能至关重要的受体的功能，以及环核苷酸磷酸二酯酶在这些受体产生的信号中的作用。鉴于制药行业开发各种适应症的磷酸二酯酶抑制剂的计划很多，更好地了解这些靶点在信号转导中的作用将为更安全、更特异的药物提供合理的基础。随着对磷酸二酯酶亚型功能的更好理解，新的治疗机会将开启，因为影响单一异构体的药物可能比非选择性抑制剂具有相当大的治疗优势。最后，这些研究将为寻找与心源性猝死和其他心血管疾病风险增加相关的人类磷酸二酯酶基因等位基因提供数据基础。

DESCRIPTION (provided by applicant): With this proposal, we intend to test the overall hypothesis that type 4 cyclic nucleotide phosphodiesterases (PDE4s) are essential for cAMP homeostasis and receptor signaling specificity. There is ample pharmacological evidence that PDE4s contribute to the shaping of the cAMP signals arising form ¿ adrenergic, prostaglandin, and gonadotropin receptors. However, the function of individual PDE4 isoforms in a cell is largely unknown. The presence of four PDE4 genes and more than twenty splicing variants prompts the question of the functional significance of such a complexity. We propose that different PDE4 variants function in macromolecular complexes to specify signals that control most biological processes, including excitation/contraction coupling in cardiomyocytes. These complexes contribute to the divergent biological responses associated with ¿1 and ¿2 adrenergic receptors. Indeed, our analysis of PDE4 KO phenotypes has provided initial evidence that PDE4D and PDE4B play distinct functions in the body. A late onset cardiomyopathy associated with arrhythmias and cardiac failure after PDE4D ablation implies that removal of a single PDE4 produces subtle but critical losses of function in the heart. The goal of this proposal is to understand the nature and consequences of these defects, as they will provide a better understanding of the properties of cAMP signaling and to predict the outcome of pharmacological interventions targeting this signaling pathway. Genetic and biochemical approaches will be used to understand the interactions of PDE4s with ¿1 and ¿2 adrenergic receptors. The experimental plan is developed along three Specific Aims. With the first aim we will probe the role of PDE4D activation in ¿-adrenergic signaling and their function. The second specific aim will be devoted to the analysis of the ¿AR/PDE4 complexes and their role in receptor function. The last specific aim will probe the effect of disruption of these complexes on the function of cardiomyocytes in vitro and in vivo. In addition to shedding new light on sympathetic regulations of the cardiac function, these studies will provide rational basis for novel therapeutic strategies that target PDE and cAMP signaling. PUBLIC HEALTH RELEVANCE: The proposed experiments will shed light on the function of receptors essential for cardiac function and the role of cyclic nucleotide phosphodiesterases in the signals arising from these receptors. In view of the large number of programs in the pharmaceutical industry developing phosphodiesterase inhibitors for a variety of indications, a better understanding of the role of these targets in signaling will provide a rational basis for safer and more specific drugs. New therapeutic opportunities will open with a better understanding of the function of phosphodiesterase subtypes, as drugs affecting single isoforms may have considerable therapeutic advantages over non selective inhibitors. Finally, these studies will provide the foundation of data on which to search for human alleles of phosphodiesterase genes associated with increased risk for sudden cardiac death and other cardiovascular disorders.