Beletkaia Elena, Fenz Susanne F, Pomp Wim, Snaar-Jagalska B Ewa, Hogendoorn Pancras W C, Schmidt Thomas
Kammerlingh Onnes-Huygens Laboratory, Leiden University, Niels Bohrweg 2, 2333 CA, Leiden, The Netherlands.
Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Germany.
Biochim Biophys Acta. 2016 Apr;1863(4):607-16. doi: 10.1016/j.bbamcr.2015.12.020. Epub 2015 Dec 31.
Understanding of the regulation mechanisms of CXCR4 signaling is essential for revealing its role in physiological and pathological processes. Though biochemical pathways following CXCR4 activation by its ligand CXCL12 are well established, knowledge about the receptor dynamics on the plasma membrane remains limited. Here we used Ewing sarcoma-derived cells to unravel the processes that are involved in regulating CXCR4 dynamics on the plasma membrane during receptor signaling. Single-molecule epi-fluorescence microscopy showed that CXCR4 was present in monomeric state on the plasma membrane independent of receptor stimulation. However, upon activation freely diffusing receptors were immobilized in a ligand concentration-dependent manner. CXCR4 immobilization was strongly correlated with the ability for G-protein signaling and was a precursor of subsequent endocytotic events. Our data suggest that, a balanced regulation of G-protein dependent and independent pathways is required for controlling CXCR4 receptor mobility, and potentially subsequent controlled signal transduction.
了解CXCR4信号的调控机制对于揭示其在生理和病理过程中的作用至关重要。尽管其配体CXCL12激活CXCR4后的生化途径已得到充分确立，但关于质膜上受体动态变化的知识仍然有限。在这里，我们使用尤因肉瘤衍生细胞来阐明在受体信号传导过程中参与调节质膜上CXCR4动态变化的过程。单分子落射荧光显微镜显示，CXCR4以单体状态存在于质膜上，与受体刺激无关。然而，激活后，自由扩散的受体以配体浓度依赖的方式被固定。CXCR4的固定与G蛋白信号传导能力密切相关，并且是随后内吞事件的前奏。我们的数据表明，控制CXCR4受体的流动性以及潜在的后续受控信号转导需要对G蛋白依赖性和非依赖性途径进行平衡调节。
