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_s-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_s-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.

中文翻译：

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内在的TSH受体在进入TGN的过程中会诱导局部Gs蛋白信号传导和基因转录。

最近出现了在细胞内位点的G蛋白偶联受体（GPCR）信号转导的新范式，但潜在的机制和功能后果尚不充分了解。在这里，我们表明，在甲状腺细胞内化后，内源性TSH受体逆行至反式高尔基体网络（TGN）并激活内源性G _s-带有逆转录子涂层的区隔中的蛋白质将其带入TGN。受体内在化与高尔基体/ TGN的晚期cAMP /蛋白激酶A（PKA）反应相关。阻断受体内在化，抑制PKA II /干扰其高尔基体/ TGN的定位，沉默改造者或破坏高尔基体/ TGN的组织都损害了有效的TSH依赖性cAMP反应元件结合蛋白（CREB）磷酸化。这些结果表明，向TGN的逆行贩运会诱发局部G _s-蛋白激活和cAMP / PKA信号在细胞核附近的关键位置出现，这似乎是有效CREB磷酸化和基因转录所必需的。这为解释GPCR信号在细胞内位点的功能后果提供了新的机制，并揭示了TGN在GPCR信号中的关键作用。最近的研究表明，G蛋白偶联受体（GPCR）可以在细胞内运输过程中发出信号。在这里，作者使用荧光显微镜方法直接在Golgi / trans-Golgi网络上可视化和研究GPCR介导的信号传导的功能后果。