Interactions of LSECtin and DC-SIGN/DC-SIGNR with viral ligands: Differential pH dependence, internalization and virion binding

Virology. 2008 Mar 30;373(1):189-201. doi: 10.1016/j.virol.2007.11.001. Epub 2008 Feb 20.

Abstract

The calcium-dependent lectins DC-SIGN and DC-SIGNR (collectively termed DC-SIGN/R) bind to high-mannose carbohydrates on a variety of viruses. In contrast, the related lectin LSECtin does not recognize mannose-rich glycans and interacts with a more restricted spectrum of viruses. Here, we analyzed whether these lectins differ in their mode of ligand engagement. LSECtin and DC-SIGNR, which we found to be co-expressed by liver, lymph node and bone marrow sinusoidal endothelial cells, bound to soluble Ebola virus glycoprotein (EBOV-GP) with comparable affinities. Similarly, LSECtin, DC-SIGN and the Langerhans cell-specific lectin Langerin readily bound to soluble human immunodeficiency virus type-1 (HIV-1) GP. However, only DC-SIGN captured HIV-1 particles, indicating that binding to soluble GP is not necessarily predictive of binding to virion-associated GP. Capture of EBOV-GP by LSECtin triggered ligand internalization, suggesting that LSECtin like DC-SIGN might function as an antigen uptake receptor. However, the intracellular fate of lectin-ligand complexes might differ. Thus, exposure to low-pH medium, which mimics the acidic luminal environment in endosomes/lysosomes, released ligand bound to DC-SIGN/R but had no effect on LSECtin interactions with ligand. Our results reveal important differences between pathogen capture by DC-SIGN/R and LSECtin and hint towards different biological functions of these lectins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Adhesion Molecules / metabolism*
  • Cell Line
  • Ebolavirus / metabolism
  • Ebolavirus / pathogenicity
  • Endothelial Cells / metabolism
  • HIV-1 / metabolism
  • HIV-1 / pathogenicity
  • HeLa Cells
  • Humans
  • Hydrogen-Ion Concentration
  • Lectins, C-Type / metabolism*
  • Ligands*
  • Plasmids / genetics
  • Receptors, Cell Surface / metabolism*
  • Viral Envelope Proteins / genetics
  • Viral Envelope Proteins / metabolism*
  • Virion / metabolism
  • Virus Internalization
  • env Gene Products, Human Immunodeficiency Virus / genetics
  • env Gene Products, Human Immunodeficiency Virus / metabolism*

Substances

  • CLEC4G protein, human
  • CLEC4M protein, human
  • Cell Adhesion Molecules
  • DC-specific ICAM-3 grabbing nonintegrin
  • Lectins, C-Type
  • Ligands
  • Receptors, Cell Surface
  • Viral Envelope Proteins
  • env Gene Products, Human Immunodeficiency Virus
  • envelope glycoprotein, Ebola virus