Regulation and Function of Cyclic Nucleotide Phosphodiesterase in Cardiac Biology and Disease

摘要-心力衰竭是一种多因素疾病，其特征是心室肥厚，心肌细胞死亡， 纤维化和收缩功能障碍。环核苷酸第二信使cAMP和cGMP调节 心脏中的许多生理功能和病理过程，从短期肌肉到 收缩/松弛到长期的结构重塑。CAMP/cGMP动态平衡失调 牵涉到各种疾病。CAMP/cGMP不能自由扩散。它们以多个空间离散的形式存在 和功能不同的环核苷酸“池”，它们被认为与不同的多蛋白质有关 每个复合体都包含独特的环化酶、磷酸二酯酶(PDE)和其他信号分子。PDE， 通过催化降解反应，是维持动态平衡、区隔和 环核苷酸介导的信号和功能的特异性。越来越多的证据表明 不同PDE表达/激活的变化代表了许多 疾病。PDE10A基因编码的同工酶能够在无细胞体系中同时降解cAMP和cGMP。 在生理条件下，PDE10A在脑内的纹状体表达丰富。大多数研究都是为了 DATE专注于神经疾病，导致PDE10A抑制剂进入临床试验 精神分裂症。然而，PDE10A在外周系统中的作用仍然知之甚少。最近， 我们首次报道了PDE10A在人和小鼠衰竭心脏中的诱导表达。使用遗传 和药理学方法，我们已经证明PDE10A在压力超载中发挥关键作用- 诱导小鼠心力衰竭。然而，其细胞和分子机制仍不清楚。 PDE10A缺乏/抑制对心脏的保护作用环核苷酸的同一性和来源 在细胞质雄性不育中，受PDE10A调控的基因仍未确定。我们的初步数据支持PDE10A的假设 抑制通过以下途径独特地促进D2AR-D2R异二聚化和D2R/Barr2信号的偏向激活 增强A2AR/cAMP/PKA介导的D2R磷酸化。D2R/baar2信号通路导致B56d-PP2A 激活，HDAC5核输入，和心肌肥大和死亡的最终减弱。为了检验我们的假设， 我们提出了两个目标：(1)利用体外实验确定PDE10A在CMS中的功能和潜在机制 细胞模型；(2)确定CM特异性PDE10A和A2AR-D2R信号在心肌缺血损伤中的作用 以及体内的重塑。我们的发现将为环核苷酸的独特来源提供新的见解， GPCRs和由PDE10A在CMS中特定调控的信号通路；以及促进我们的 了解D2R信号在心脏组织中的新作用。确定特定的环核苷酸信号 PDE10A可通过靶向PDE10A促进新的治疗策略的发展 与其他环核苷酸调节剂结合，以更少的成本实现相加或协同效应 有害的副作用。

ABSTRACT - Heart failure is a multifactorial disease, characterized by ventricular hypertrophy, myocyte death, fibrosis, and contractile dysfunction. Cyclic nucleotide second messengers, cAMP and cGMP, regulate numerous physiological functions and pathological processes in the heart, ranging from short-term muscle contraction/relaxation to long-term structural remodeling. Dysregulated cAMP/cGMP homeostasis has been implicated in various diseases. cAMP/cGMP are NOT freely diffusible. They exist as multiple spatially discrete and functionally distinct cyclic nucleotide “pools”, which is believed to associate with different multi-protein complexes each containing unique cyclases, phosphodiesterases (PDEs), and other signaling molecules. PDEs, by catalyzing the degradation reaction, are essential for maintaining homeostasis, compartmentalization, and specificity of cyclic nucleotide-mediated signaling and functions. Increasing evidence has indicated that alterations in the expression/activation of different PDEs represent causative mechanisms for a number of diseases. PDE10A gene encoded isozymes are able to hydrolyze both cAMP and cGMP in cell-free systems. Under the physiological condition, PDE10A expression is enriched in the striatum of the brain. Most studies to date have focused on neurological diseases, leading to advancing PDE10A inhibitors to clinical trials for schizophrenia. However, the roles of PDE10A in the peripheral systems are still poorly understood. Recently, we have first reported the induction of PDE10A expression in human and mouse failing hearts. Using genetic and pharmacological approaches, we have demonstrated that PDE10A plays a critical role in pressure overload- induced heart failure in mice. However, the cellular and molecular mechanisms remain unclear with respect to the protective effects of PDE10A deficiency/inhibition in the heart. The identity and source of the cyclic nucleotide regulated by PDE10A in CMs remain uncharacterized. Our preliminary data support a hypothesis that PDE10A inhibition uniquely promotes A2AR-D2R heterodimerization and biased activation of D2R/barr2 signaling through potentiating A2AR/cAMP/PKA-mediated phosphorylation of D2R. D2R/baar2 signaling leads to B56d-PP2A activation, HDAC5 nuclear import, and ultimate attenuation of CM hypertrophy and death. To test our hypothesis, we propose two aims: (1) determine the functionsand underlying mechanism of PDE10A in CMs using in vitro cellular models; (2) determine the role of CM-specific PDE10A and A2AR-D2R signaling in cardiac ischemic injury and remodeling in vivo. Our findings will provide the novel insights into the unique sources of cyclic nucleotides, GPCRs, and signaling pathways that are specifically regulated by PDE10A in CMs; as well as advance our understanding the novel roles of D2R signaling in cardiac tissues. Defining the specific cyclic nucleotide signaling modulated by PDE10A may facilitate the development of novel therapeutic strategies through targeting PDE10A in combination with other cyclic nucleotide modulators to achieve additive or synergistic effects with less deleterious side effects.