Difference in fine specificity to polysaccharides of Candida albicans mannoprotein between mouse SIGNR1 and human DC-SIGN

Infect Immun. 2012 May;80(5):1699-706. doi: 10.1128/IAI.06308-11. Epub 2012 Feb 13.

Abstract

C-type lectin SIGNR1 directly recognizes Candida albicans and zymosan and has been considered to share properties of polysaccharide recognition with human DC-SIGN (hDC-SIGN). However, the precise specificity of SIGNR1 and the difference from that of hDC-SIGN remain to be elucidated. We prepared soluble forms of SIGNR1 and hDC-SIGN and conducted experiments to examine their respective specificities. Soluble SIGNR1 (sSIGNR1) bound several types of live C. albicans clinical isolate strains in an EDTA-sensitive manner. Inhibition analyses of sSIGNR1 binding by glycans from various yeast strains demonstrated that SIGNR1 preferentially recognizes N-glycan α-mannose side chains in Candida mannoproteins, as reported in hDC-SIGN. Unlike shDC-SIGN, however, sSIGNR1 recognized not only Saccharomyces cerevisiae, but also C. albicans J-1012 glycan, even after α-mannosidase treatment that leaves only β1,2-mannose-capped α-mannose side chains. In addition, glycomicroarray analyses showed that sSIGNR1 binds mannans from C. albicans and S. cerevisiae but does not recognize Lewis(a/b/x/y) antigen polysaccharides as in shDC-SIGN. Consistent with these results, RAW264.7 cells expressing hDC-SIGN in which the carbohydrate recognition domain (CRD) was replaced with that of SIGNR1 (RAW-chimera) produced comparable amounts of interleukin 10 (IL-10) in response to glycans from C. albicans and S. cerevisiae, but those expressing hDC-SIGN produced less IL-10 in response to S. cerevisiae than C. albicans. Furthermore, RAW-hDC-SIGN cells remarkably reduced IL-10 production after α-mannosidase treatment compared with RAW-chimera cells. These results indicate that SIGNR1 recognizes C. albicans/yeast through a specificity partly distinct from that of its homologue hDC-SIGN.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Candida albicans / immunology*
  • Candida albicans / metabolism*
  • Cell Adhesion Molecules / metabolism*
  • Gene Expression Regulation
  • HEK293 Cells
  • Humans
  • Interleukin-10 / genetics
  • Interleukin-10 / metabolism
  • Lectins, C-Type / metabolism*
  • Macrophages
  • Mice
  • Polysaccharides / chemistry
  • Polysaccharides / metabolism*
  • Protein Binding
  • Receptors, Cell Surface / metabolism*
  • Recombinant Proteins
  • Saccharomyces cerevisiae

Substances

  • Cell Adhesion Molecules
  • DC-specific ICAM-3 grabbing nonintegrin
  • Lectins, C-Type
  • Polysaccharides
  • Receptors, Cell Surface
  • Recombinant Proteins
  • Interleukin-10