title: Characterization of the duplicate L-SIGN and DC-SIGN genes in miiuy croaker and evolutionary analysis of L-SIGN in fishes.
abstract: Dendritic cell-specific ICAM-3-grabbing non-integrin (DC-SIGN/CD209) and liver/lymph node-specific ICAM-grabbing non-integrin (L-SIGN/CD299) which are homologues of DC-SIGN are important members in C-type lectin receptors family as key molecules to recognize and eliminate pathogens in the innate immune system. DC-SIGN and L-SIGN have become hot topics in recent studies which both served as cell adhesion and phagocytic pathogen recognition receptors in mammals. However, there have been almost no studies of DC-SIGN and L-SIGN structure and characters in fish, only DC-SIGN in the zebrafish had been studied. In our study, we identified and characterized the full-length miiuy croaker (Miichthys miiuy) DC-SIGN (mmDC-SIGN) and L-SIGN (mmL-SIGN) genes. The sequence analysis results showed that mmDC-SIGN and mmL-SIGN have the same domains with other vertebrates except primates, and share some conserved motifs in CRD among all the vertebrates which play a crucial role in interacting with Ca(2+) and for recognizing mannose-containing motifs. Gene synteny of DC-SIGN and L-SIGN were analyzed for the first time and gene synteny of L-SIGN was conserved among the five fishes. Interestingly, one gene next to L-SIGN from gene synteny had high similarity with L-SIGN gene that was described as L-SIGN-like in fish species. While only one L-SIGN gene existed in other vertebrates, two L-SIGN in fish may be in consequence of the fish-specific genome duplication to adapt the specific environment. The evolutionary analysis showed that the ancestral lineages of L-SIGN gene in fishes experienced purifying selection and the current lineages of L-SIGN gene in fishes underwent positive selection, indicating that the ancestral lineages and current lineages of L-SIGN gene in fishes underwent different evolutionary patterns. Both mmDC-SIGN and mmL-SIGN were expressed in all tested tissues and ubiquitously up-regulated in infected liver, spleen and kidney at different sampling time points, indicating that the mmDC-SIGN and mmL-SIGN participated in the immune response to defense against bacteria infection.
authors.affiliation: Laboratory of Fish Biogenetics & Immune Evolution, College of Marine Science, Zhejiang Ocean University, Zhoushan 316022, China.
authors.forename: Chang
authors.initials: C
authors.lastname: Shu
authors.affiliation: Laboratory of Fish Biogenetics & Immune Evolution, College of Marine Science, Zhejiang Ocean University, Zhoushan 316022, China.
authors.forename: Shanchen
authors.initials: S
authors.lastname: Wang
authors.affiliation: Laboratory of Fish Biogenetics & Immune Evolution, College of Marine Science, Zhejiang Ocean University, Zhoushan 316022, China. Electronic address: tianjunxu@163.com.
authors.forename: Tianjun
authors.initials: T
authors.lastname: Xu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019143:Evolution, Molecular; D029941:Fish Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005399:Fishes / Q000235:genetics*; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008969:Molecular Sequence Data; D010473:Perciformes / Q000235:genetics*; D010802:Phylogeny; D013154:Spleen / Q000378:metabolism
chemical_list: D029941:Fish Proteins
keywords: DC-SIGN; Evolutionary analysis; Expression patterns; Gene synteny; L-SIGN; Miiuy croaker