title: Distribution and lateral mobility of DC-SIGN on immature dendritic cells--implications for pathogen uptake.
abstract: The receptor C-type lectin DC-SIGN (CD209) is expressed by immature dendritic cells, functioning as an antigen capture receptor and cell adhesion molecule. Various microbes, including HIV-1, can exploit binding to DC-SIGN to gain entry to dendritic cells. DC-SIGN forms discrete nanoscale clusters on immature dendritic cells that are thought to be important for viral binding. We confirmed that these DC-SIGN clusters also exist both in live dendritic cells and in cell lines that ectopically express DC-SIGN. Moreover, DC-SIGN has an unusual polarized lateral distribution in the plasma membrane of dendritic cells and other cells: the receptor is preferentially localized to the leading edge of the dendritic cell lamellipod and largely excluded from the ventral plasma membrane. Colocalization of DC-SIGN clusters with endocytic activity demonstrated that surface DC-SIGN clusters are enriched near the leading edge, whereas endocytosis of these clusters occurred preferentially at lamellar sites posterior to the leading edge. Therefore, we predicted that DC-SIGN clusters move from the leading edge to zones of internalization. Two modes of lateral mobility were evident from the trajectories of DC-SIGN clusters at the leading edge, directed and non-directed mobility. Clusters with directed mobility moved in a highly linear fashion from the leading edge to rearward locations in the lamella at remarkably high velocity (1420+/-260 nm/second). Based on these data, we propose that DC-SIGN clusters move from the leading edge--where the dendritic cell is likely to encounter pathogens in tissue--to a medial lamellar site where clusters enter the cell via endocytosis. Immature dendritic cells may acquire and internalize HIV and other pathogens by this process.
authors.affiliation: Department of Cell and Developmental Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
authors.forename: Aaron K
authors.initials: AK
authors.lastname: Neumann
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Thompson
authors.forename: Ken
authors.initials: K
authors.lastname: Jacobson
mesh_terms: D000818:Animals; D017951:Antigen Presentation / Q000276:immunology; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D002465:Cell Movement / Q000276:immunology; D016764:Cell Polarity / Q000276:immunology; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000276:immunology*; D004705:Endocytosis / Q000276:immunology*; D015497:HIV-1 / Q000276:immunology; D006801:Humans; D037181:Lectins, C-Type / Q000378:metabolism*; D021962:Membrane Microdomains / Q000276:immunology; D051379:Mice; D041681:NIH 3T3 Cells; D010587:Phagocytosis / Q000276:immunology; D021381:Protein Transport / Q000276:immunology; D011554:Pseudopodia / Q000276:immunology / Q000648:ultrastructure; D011940:Receptor Aggregation / Q000276:immunology*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D013234:Stem Cells / Q000276:immunology*; D000099215:DC-Specific ICAM-3 Grabbing Nonintegrin
chemical_list: D015815:Cell Adhesion Molecules; D037181:Lectins, C-Type; D011956:Receptors, Cell Surface; D000099215:DC-Specific ICAM-3 Grabbing Nonintegrin