Identification and expression analysis of the leukocyte cell-derived chemotaxin-2 (LECT2) gene in duck (Anas platyrhynchos)

Abstract

Leukocyte cell-derived chemotaxin 2 (LECT2), first identified as a chemotactic factor, is involved in the regulation of liver regeneration, carcinogenesis, and natural killer T-cell homeostasis in mammals. The function of LECT2 in the duck remains unclear, however. A suppression subtractive cDNA library was constructed from the livers of 3-day-old ducklings treated with duck hepatitis virus type I (DHV-1). A total of 66 expressed sequence tags (ESTs) were identified in the libraries. Among the novel gene fragments identified was the LECT2 gene. Full-length duck LECT2 (duLECT2) complementary DNA (cDNA) was obtained using the reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of the cDNA ends (RACE). The cDNA consisted of a 50 nucleotide 5′ untranslated region (UTR), an 84 nucleotide 3′ UTR, and a 1020 nucleotide open reading frame encoding a single protein of 339 amino acids. In agreement with a previously reported LECT2 sequence, the predicted amino acid sequence contains characteristic phosphorylation and N-glycosylation sites. DuLECT2 is highly similar to LECT2 genes from other vertebrates. Phylogenetic analysis demonstrated that the LECT2 gene has been highly conserved throughout vertebrate evolution. RT-PCR analyses revealed that duLECT2 mRNA is widely expressed in healthy tissues. They also showed that duLECT2 mRNA is significantly up-regulated in the liver and spleen following injection with DHV-1 or polyriboinosinic polyribocytidylic acid (poly I:C), peaking 4 or 12h post-challenge in the liver and spleen, respectively, and afterwards gradually returning to normal. Our findings suggest that duLECT2 contributes to the innate immune response against viral infections.