Abstract:
Dendritic-cell-specific ICAM-3-grabbing non-integrin (DC-SIGN) is a C-type lectin that functions as a
pattern recognition receptor by recognizing pathogen-associated molecular patterns (PAMPs). It is also
involved in various events of the dendritic cell (DC) life cycle, such as DC migration, antigen capture and
presentation, and T cell priming. In this study, a DC-SIGN-like gene from the big belly seahorse Hippocampus abdominalis (designated as ShDCS-like) was identified and molecularly characterized. The putative, complete ORF was found to be 1368 bp in length, encoding a protein of 462 amino acids with a
molecular mass of 52.6 kDa and a theoretical isoelectric point of 8.26. The deduced amino acid sequence
contains a single carbohydrate recognition domain (CRD), in which six conserved cysteine residues and
two Ca2þ-binding site motifs (QPN, WND) were identified. Based on pairwise sequence analysis, ShDCSlike exhibits the highest amino acid identity (94.6%) and similarity (97.4%) with DC-SIGN-like counterpart
from tiger tail seahorse Hippocampus comes. Quantitative real-time PCR revealed that ShDCS-like mRNA is
transcribed universally in all tissues examined, but with abundance in kidney and gill tissues. The basal
mRNA expression of ShDCS-like was modulated in blood cell, kidney, gill and liver tissues in response to
the stimulation of healthy fish with lipopolysaccharides (LPS), Edwardsiella tarda, or Streptococcus iniae.
Moreover, recombinant ShDCS-like-CRD domain exhibited detectable agglutination activity against
different bacteria. Collectively, these results suggest that ShDCS-like may potentially involve in immune
function in big belly seahorses.
