title: Intracellular localization and constitutive endocytosis of CXCR4 in human CD34+ hematopoietic progenitor cells.
abstract: CXCR4, the stromal cell-derived factor-1 receptor, plays an important role in the migration of hematopoietic progenitor/stem cells. The surface and cytoplasmic expression of CXCR4 on human hematopoietic CD34(+) cells was investigated. We show that its surface expression is low, whereas a large part of CXCR4 protein is sequestered intracellularly. Using confocal microscopy, we demonstrated that CXCR4 is colocalized with EEA-1, Rab5, Rab4, and Rab11, which are localized in early and recycling endosomes. No significant colocalization of CXCR4 with lysosomal markers CD63 and Lamp-1 was detected. Using antibody feeding experiments, we report a role for CXCR4 constitutive endocytosis in subcellular localization in stably transduced UT7-CXCR4-GFP and CD34(+) cells. Agonist-independent endocytosis of CXCR4 occurs through clathrin-coated vesicles. These data implicate a constitutive endocytosis in the regulation of CXCR4 membrane expression and suggest that constitutive endocytosis may be involved in the regulation of trafficking the human hematopoietic progenitor/stem cells to and in the bone marrow microenvironment.
authors.affiliation: INSERM U362, Institut Gustave Roussy, PR1, 39 Rue Camille Desmoulins, 94805 Villejuif, France.
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Adlen
authors.initials: A
authors.lastname: Foudi
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Geay
authors.forename: Magali
authors.initials: M
authors.lastname: Berthebaud
authors.forename: Dorothée
authors.initials: D
authors.lastname: Buet
authors.forename: Peggy
authors.initials: P
authors.lastname: Jarrier
authors.forename: Abdelali
authors.initials: A
authors.lastname: Jalil
authors.forename: William
authors.initials: W
authors.lastname: Vainchenker
authors.forename: Fawzia
authors.initials: F
authors.lastname: Louache
mesh_terms: D015703:Antigens, CD / Q000096:biosynthesis; D018952:Antigens, CD34 / Q000096:biosynthesis*; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement; D002633:Chemotaxis; D002966:Clathrin / Q000378:metabolism; D004705:Endocytosis; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D008024:Ligands; D051907:Lysosomal Membrane Proteins; D008565:Membrane Proteins / Q000096:biosynthesis; D018613:Microscopy, Confocal; D010957:Plasmids / Q000378:metabolism; D010980:Platelet Membrane Glycoproteins / Q000096:biosynthesis; D019718:Receptors, CXCR4 / Q000096:biosynthesis*; D012190:Retroviridae / Q000235:genetics; D015398:Signal Transduction; D013696:Temperature; D060149:Tetraspanin 30; D033921:Vesicular Transport Proteins; D020691:rab GTP-Binding Proteins / Q000096:biosynthesis; D020695:rab4 GTP-Binding Proteins / Q000096:biosynthesis; D020696:rab5 GTP-Binding Proteins / Q000096:biosynthesis; D000099193:rab11 GTP-Binding Proteins
chemical_list: D015703:Antigens, CD; D018952:Antigens, CD34; D002966:Clathrin; D049452:Green Fluorescent Proteins; D008024:Ligands; D051907:Lysosomal Membrane Proteins; D008565:Membrane Proteins; D010980:Platelet Membrane Glycoproteins; D019718:Receptors, CXCR4; D060149:Tetraspanin 30; D033921:Vesicular Transport Proteins; D020691:rab GTP-Binding Proteins; D020695:rab4 GTP-Binding Proteins; D020696:rab5 GTP-Binding Proteins; D000099193:rab11 GTP-Binding Proteins; C554586:CD63 protein, human; C093846:early endosome antigen 1