Phosphodiesterases govern nuclear cAMP signaling for gene expression

摘要 研究已经确定了磷酸二酯酶(PDE)超家族在 水解型cAMP及其亚细胞分布。我们的目标是探索PDE在差异调控中的作用 质膜和细胞核内的cAMP信号。具体地说，我们将揭示 中枢β_2-肾上腺素能受体(B2AR)刺激下的海马(HC)核cAMP信号 学习和记忆过程中的神经元。有趣的是，PDE4抑制剂有益于啮齿动物的学习和记忆 和人，表明PDE4可能在细胞核内控制βAR诱导的cAMP信号。PDE4D亚型 与β2AR有关，可微调成纤维细胞和肌细胞中的亚细胞cAMP-PKA信号，以及PDE4D5 与细胞核内的AKAP95/PKA复合体有关。我们的初步数据显示，βAR刺激 促进HC神经元PDE4D5的核输出。PDE4D5的这种重新定位依赖于内体 GRK-磷酸化的B2AR，对于将cAMP信号传递到细胞核是至关重要的。除了 GRK-磷酸化的B2AR，我们最近描述了B2AR的另一个不同的亚群，它们是 在HC神经元，激动剂刺激后，PKA被磷酸化并定位于PM。我们假设有两个 B2AR亚群通过抑制3依赖的PDE4D5输出协同促进核cAMP信号 来自原子核。我们将描述PDE4D5依赖的调控机制。 核cAMP信号和基因表达及其调节如何影响学习中的B2AR信号 和记忆(目标3)。这项拟议的研究将确定PDE4D5在核cAMP信号转导基因中的作用 表达，以及学习和记忆，这不仅提供了治疗与 中枢神经系统肾上腺素能系统也为研究许多其他Gs偶联受体提供了一个例子，例如 多巴胺受体在基因表达调控中的作用

Abstract Studies have established the critical roles of a superfamily of phosphodiesterases (PDEs) in hydrolyzing cAMP and its subcellular distribution. We aim to explore the role of PDEs in differential regulation of the cAMP signals at the plasma membrane and in the nucleus. Specifically, we will uncover the regulation of the nuclear cAMP signals under the CNS β2-adrenergic receptor (b2AR) stimulation in hippocampal (HC) neurons during learning and memory. Interestingly, PDE4 inhibitors benefit learning and memory in rodents and humans, indicating that PDE4 may control the βAR-induced cAMP signal in the nucleus. PDE4D isoforms are associated with β2AR to fine-tune subcellular cAMP-PKA signals in fibroblasts and myocytes, and PDE4D5 is associated with an AKAP95/PKA complex in the nucleus. Our preliminary data show that βAR stimulation promotes the nuclear export of PDE4D5 in HC neurons. This relocation of PDE4D5 depends on endosome GRK-phosphorylated b2AR and is critically necessary for delivering cAMP signals into the nucleus. Besides the GRK-phosphorylated b2AR, we have recently characterized another distinct subpopulation of b2AR that are PKA-phosphorylated and located at the PM after agonist stimulation in HC neurons. We hypothesize that two b2AR subpopulations synergistically promote nuclear cAMP signal by arrestin3-dependent export of PDE4D5 from the nucleus. We will characterize the mechanisms underlying the PDE4D5-dependent regulation of nuclear cAMP signaling and gene expression and how the regulation may affect the b2AR signaling in learning and memory (Aim 3). This proposed study will define the role of PDE4D5 in nuclear cAMP signaling, gene expression, and learning and memory, which not only offer new strategies to treat disorders associated with the CNS adrenergic system but also offer an example to study many other Gs-coupled receptors, such as dopamine receptors in the regulation of gene expression.