title: DC-SIGN and influenza hemagglutinin dynamics in plasma membrane microdomains are markedly different.
abstract: DC-SIGN, a Ca(2+)-dependent transmembrane lectin, is found assembled in microdomains on the plasma membranes of dendritic cells. These microdomains bind a large variety of pathogens and facilitate their uptake for subsequent antigen presentation. In this study, DC-SIGN dynamics in microdomains were explored with several fluorescence microscopy methods and compared with dynamics for influenza hemagglutinin (HA), which is also found in plasma membrane microdomains. Fluorescence imaging indicated that DC-SIGN microdomains may contain other C-type lectins and that the DC-SIGN cytoplasmic region is not required for microdomain formation. Fluorescence recovery after photobleaching measurements showed that neither full-length nor cytoplasmically truncated DC-SIGN in microdomains appreciably exchanged with like molecules in other microdomains and the membrane surround, whereas HA in microdomains exchanged almost completely. Line-scan fluorescence correlation spectroscopy indicated an essentially undetectable lateral mobility for DC-SIGN but an appreciable mobility for HA within their respective domains. Single-particle tracking with defined-valency quantum dots confirmed that HA has significant mobility within microdomains, whereas DC-SIGN does not. By contrast, fluorescence recovery after photobleaching indicated that inner leaflet lipids are able to move through DC-SIGN microdomains. The surprising stability of DC-SIGN microdomains may reflect structural features that enhance pathogen uptake either by providing high-avidity platforms and/or by protecting against rapid microdomain endocytosis.
authors.affiliation: Department of Cell and Developmental Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors.forename: Michelle S
authors.initials: MS
authors.lastname: Itano
authors.forename: Aaron K
authors.initials: AK
authors.lastname: Neumann
authors.forename: Ping
authors.initials: P
authors.lastname: Liu
authors.forename: Feng
authors.initials: F
authors.lastname: Zhang
authors.forename: Enrico
authors.initials: E
authors.lastname: Gratton
authors.forename: Wolfgang J
authors.initials: WJ
authors.lastname: Parak
authors.forename: Nancy L
authors.initials: NL
authors.lastname: Thompson
authors.forename: Ken
authors.initials: K
authors.lastname: Jacobson
mesh_terms: D015815:Cell Adhesion Molecules / Q000737:chemistry / Q000378:metabolism*; D002966:Clathrin / Q000378:metabolism; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000737:chemistry / Q000378:metabolism*; D037181:Lectins, C-Type / Q000737:chemistry / Q000378:metabolism*; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins / Q000378:metabolism; D021962:Membrane Microdomains / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D009068:Movement; D009419:Nerve Tissue Proteins / Q000378:metabolism; D021381:Protein Transport; D045663:Quantum Dots; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000378:metabolism*; D000099215:DC-Specific ICAM-3 Grabbing Nonintegrin; D000099181:Dectin-1
chemical_list: D015815:Cell Adhesion Molecules; D002966:Clathrin; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D037181:Lectins, C-Type; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D011956:Receptors, Cell Surface; D000099215:DC-Specific ICAM-3 Grabbing Nonintegrin; D000099181:Dectin-1