Key Laboratory of Molecular Target and Clinical Pharmacology, State Key Laboratory of Respiratory Disease, School of Pharmaceutical Sciences & the Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China.
Department of Pharmacology, University of California Davis, Davis, United States.
Elife. 2019 Oct 14;8:e49464. doi: 10.7554/eLife.49464.
G protein-coupled receptors (GPCRs) transduce pleiotropic intracellular signals in mammalian cells. Here, we report neuronal excitability of β-blockers carvedilol and alprenolol at clinically relevant nanomolar concentrations. Carvedilol and alprenolol activate βAR, which promote G protein signaling and cAMP/PKA activities without action of G protein receptor kinases (GRKs). The cAMP/PKA activities are restricted within the immediate vicinity of activated βAR, leading to selectively enhance PKA-dependent phosphorylation and stimulation of endogenous L-type calcium channel (LTCC) but not AMPA receptor in rat hippocampal neurons. Moreover, we have engineered a mutant βAR that lacks the catecholamine binding pocket. This mutant is preferentially activated by carvedilol but not the orthosteric agonist isoproterenol. Carvedilol activates the mutant βAR in mouse hippocampal neurons augmenting LTCC activity through cAMP/PKA signaling. Together, our study identifies a mechanism by which β-blocker-dependent activation of GPCRs promotes spatially restricted cAMP/PKA signaling to selectively target membrane downstream effectors such as LTCC in neurons.
G 蛋白偶联受体（GPCRs）在哺乳动物细胞中转导多种细胞内信号。在这里，我们报告了β受体阻滞剂卡维地洛和阿普洛尔在临床相关的纳摩尔浓度下对神经元兴奋性的影响。卡维地洛和阿普洛尔激活βAR，促进 G 蛋白信号和 cAMP/PKA 活性，而无需 G 蛋白受体激酶（GRKs）的作用。cAMP/PKA 活性局限于激活的βAR 附近，导致选择性增强 PKA 依赖性磷酸化和刺激内源性 L 型钙通道（LTCC），而不是大鼠海马神经元中的 AMPA 受体。此外，我们构建了一种缺乏儿茶酚胺结合口袋的突变βAR。这种突变体被卡维地洛优先激活，而不是激动剂异丙肾上腺素。卡维地洛在小鼠海马神经元中激活突变βAR，通过 cAMP/PKA 信号转导增强 LTCC 活性。总之，我们的研究确定了一种机制，即β受体阻滞剂依赖性 GPCR 激活促进空间受限的 cAMP/PKA 信号转导，以选择性地靶向神经元中的膜下游效应器，如 LTCC。
