Godbole Amod, Lyga Sandra, Lohse Martin J, Calebiro Davide
Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, 97078, Germany.
Bio-Imaging Center/Rudolf Virchow Center, University of Würzburg, Würzburg, Germany.
Nat Commun. 2017 Sep 5;8(1):443. doi: 10.1038/s41467-017-00357-2.
A new paradigm of G-protein-coupled receptor (GPCR) signaling at intracellular sites has recently emerged, but the underlying mechanisms and functional consequences are insufficiently understood. Here, we show that upon internalization in thyroid cells, endogenous TSH receptors traffic retrogradely to the trans-Golgi network (TGN) and activate endogenous G-proteins in the retromer-coated compartment that brings them to the TGN. Receptor internalization is associated with a late cAMP/protein kinase A (PKA) response at the Golgi/TGN. Blocking receptor internalization, inhibiting PKA II/interfering with its Golgi/TGN localization, silencing retromer or disrupting Golgi/TGN organization all impair efficient TSH-dependent cAMP response element binding protein (CREB) phosphorylation. These results suggest that retrograde trafficking to the TGN induces local G-protein activation and cAMP/PKA signaling at a critical position near the nucleus, which appears required for efficient CREB phosphorylation and gene transcription. This provides a new mechanism to explain the functional consequences of GPCR signaling at intracellular sites and reveals a critical role for the TGN in GPCR signaling.Recent investigations suggest that G-protein-coupled receptors (GPCRs) can signal during intracellular trafficking. Here the authors use fluorescence microscopy approaches to directly visualize and investigate functional consequences of GPCR-mediated signaling at the Golgi/trans-Golgi network.
一种关于G蛋白偶联受体（GPCR）在细胞内位点信号传导的新范式最近出现了，但其潜在机制和功能后果尚未得到充分理解。在这里，我们表明，在甲状腺细胞内化后，内源性促甲状腺激素（TSH）受体逆行运输至反式高尔基体网络（TGN），并在将它们带至TGN的回收蛋白包被区室中激活内源性G蛋白。受体内化与高尔基体/TGN处的晚期环磷酸腺苷（cAMP）/蛋白激酶A（PKA）反应相关。阻断受体内化、抑制PKA II/干扰其在高尔基体/TGN的定位、使回收蛋白沉默或破坏高尔基体/TGN组织，均会损害有效的TSH依赖性cAMP反应元件结合蛋白（CREB）磷酸化。这些结果表明，逆行运输至TGN会在细胞核附近的关键位置诱导局部G蛋白激活以及cAMP/PKA信号传导，这似乎是有效的CREB磷酸化和基因转录所必需的。这提供了一种新机制来解释GPCR在细胞内位点信号传导的功能后果，并揭示了TGN在GPCR信号传导中的关键作用。最近的研究表明，G蛋白偶联受体（GPCR）可在细胞内运输过程中发出信号。本文作者使用荧光显微镜方法直接观察并研究了GPCR介导的信号在高尔基体/反式高尔基体网络中的功能后果。
