Phosphodiesterases govern nuclear cAMP signaling for gene expression

摘要 研究已经确定了磷酸二酯酶（PDE）超家族在以下方面的关键作用： 水解cAMP及其亚细胞分布。我们的目的是探讨偏微分方程在差异调节中的作用 细胞膜和细胞核中cAMP信号的变化。具体来说，我们将揭示 中枢神经系统β_2-肾上腺素能受体（b_2AR）刺激海马（HC）核cAMP信号 神经元在学习和记忆中的作用。有趣的是，PDE 4抑制剂有利于啮齿动物的学习和记忆。 这表明PDE 4可能控制β AR诱导的细胞核cAMP信号。PDE 4D亚型 与β 2 AR相关，以微调成纤维细胞和肌细胞中的亚细胞cAMP-PKA信号，而PDE 4D 5 与细胞核中的AKAP 95/PKA复合物相关。我们的初步数据表明，βAR刺激 促进HC神经元中PDE 4D 5的核输出。PDE 4D 5的这种重新定位依赖于内体 GRK-磷酸化的b2 AR，并且是将cAMP信号传递到细胞核中所必需的。除了 GRK磷酸化b2 AR，我们最近表征了另一个不同的b2 AR亚群，它们是 在HC神经元中，激动剂刺激后PKA磷酸化并定位于PM。我们假设两个 b2 AR亚群通过抑制蛋白3依赖性PDE 4D 5输出协同促进核cAMP信号 从原子核中分离出来。我们将描述PDE 4D 5依赖性调节的机制， 核cAMP信号和基因表达以及调节如何影响学习中的b2 AR信号 记忆（目标3）这项研究将确定PDE 4D 5在核cAMP信号传导中的作用，基因表达， 表达，学习和记忆，这不仅提供了新的策略，以治疗疾病相关的 中枢神经系统肾上腺素能系统，但也提供了一个例子，研究许多其他的GS-偶联受体，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.