title: CXCR4 signaling is controlled by immobilization at the plasma membrane.
abstract: 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.
authors.affiliation: Kammerlingh Onnes-Huygens Laboratory, Leiden University, Niels Bohrweg 2, 2333 CA, Leiden, The Netherlands.
authors.forename: Elena
authors.initials: E
authors.lastname: Beletkaia
authors.affiliation: Department of Cell and Developmental Biology, Biocenter, University of Würzburg, Germany.
authors.forename: Susanne F
authors.initials: SF
authors.lastname: Fenz
authors.affiliation: Kammerlingh Onnes-Huygens Laboratory, Leiden University, Niels Bohrweg 2, 2333 CA, Leiden, The Netherlands.
authors.forename: Wim
authors.initials: W
authors.lastname: Pomp
authors.affiliation: Leiden Institute of Biology, Leiden University, Leiden, The Netherlands.
authors.forename: B Ewa
authors.initials: BE
authors.lastname: Snaar-Jagalska
authors.affiliation: Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Pancras W C
authors.initials: PW
authors.lastname: Hogendoorn
authors.affiliation: Kammerlingh Onnes-Huygens Laboratory, Leiden University, Niels Bohrweg 2, 2333 CA, Leiden, The Netherlands.
authors.forename: Thomas
authors.initials: T
authors.lastname: Schmidt
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D004705:Endocytosis / Q000235:genetics; D019204:GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D055503:Protein Multimerization; D021381:Protein Transport; D019718:Receptors, CXCR4 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics; D022161:Transport Vesicles / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: C527276:CXCR4 protein, human; D019718:Receptors, CXCR4; D019204:GTP-Binding Proteins
keywords: CXCR4; Endocytosis; Signaling; Single molecule