Identification and functional characterization of a bovine orthologue to DC-SIGN

J Leukoc Biol. 2008 Jun;83(6):1396-403. doi: 10.1189/jlb.0807523. Epub 2008 Mar 3.

Abstract

Dendritic cell-specific ICAM-3-grabbing nonintegrin (DC-SIGN) C-type lectin is almost exclusively expressed at the cell surface of DC. In addition to its normal function facilitating contact of DC with T cells, DC-SIGN has been shown to bind a variety of pathogens, including Mycobacterium bovis, and HIV-1 envelope protein gp120. In this study, we identified the bovine ortholog of the human DC-SIGN gene within the bovine genome, which exists as a single copy. PCR amplified a product, showing a 100% match with the predicted sequences as well as a sequence predicted to be similar to that of SIGNR7. Furthermore, a protein with the same molecular weight as human DC-SIGN was detected by Western blot in cell lysate derived from bovine DC. To characterize this molecule functionally, the uptake of FITC-labeled OVA and FITC-labeled gp120 (FITC-gp120) by bovine and human DC was assessed. FITC-gp120 was shown to bind to bovine DC in a time- and temperature-dependent manner. Binding was blocked by a polyclonal anti-DC-SIGN antibody but not by a control antibody. Furthermore, blocking of this molecule also reduced the binding of M. bovis bacillus Calmette-Guerin expressing GFP. Confocal microscopy showed that DC-SIGN was expressed on the surface of bovine DC. Subsequent pulse-chase studies revealed that FITC-gp120 was internalized by bovine monocyte-derived DC as early as 10 min. Thus, there is evidence of a DC-SIGN-like molecule expressed specifically by bovine DC. This molecule may play an important role in the infection of bovine (DC) cells with M. bovis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cattle / immunology*
  • Cell Adhesion Molecules / analysis*
  • Cell Adhesion Molecules / genetics
  • Cell Adhesion Molecules / physiology
  • Dendritic Cells / chemistry
  • Dendritic Cells / microbiology
  • Dendritic Cells / physiology
  • Glycoproteins / metabolism
  • Humans
  • Lectins, C-Type / analysis*
  • Lectins, C-Type / genetics
  • Lectins, C-Type / physiology
  • Monocytes / chemistry
  • Mycobacterium bovis / physiology
  • Nerve Tissue Proteins / metabolism
  • Receptors, Cell Surface / analysis*
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / physiology
  • Time Factors

Substances

  • Cell Adhesion Molecules
  • DC-specific ICAM-3 grabbing nonintegrin
  • Glycoproteins
  • Gp120 brain glycoprotein, Bos taurus
  • Lectins, C-Type
  • Nerve Tissue Proteins
  • Receptors, Cell Surface