Molecular cloning and functional characterizations of chicken TL1A

TL1A cDNA in chickens (ChTL1A), a homologue of human TL1A that belongs to the tumor necrosis factor (TNF) ligand super family, was cloned and characterized for its biological properties. The ChTL1A cDNA consisted of 1461 bp, coding for 239 amino acid residues and revealed a TNF ligand superfamily signature ([LV]-x-[LIVM]-x3-G-[LIVMF]-Y-[LIVMFY]2-x2-[QEKHL]). This cDNA sequence also had a transmembrane domain between residues 34 and 53 (VLLCLLAVLLLALPIAYLLA). mRNA for ChTL1A was detected in most of the tissues and organs sampled and the expression was increased in spleen and abdominal adipose tissue following LPS injection. Recombinant chicken TL1A protein showed cytotoxic activity to the L929 cell line and cultured chicken fibroblast cells. Injection of the TL1A protein to broiler chicks resulted in a decrease in feed intake, an increase in nitric oxide production and rectal temperature. As an homologous sequence of mammalian TNF-alpha has not been identified in the chicken genome database so far, the present data suggest that chicken TL1A possibly functions as a substitute for TNF-alpha.