Molecular characterization of the canine cytokine TWEAK (CD255) and its receptor, Fn14 (CD266)

TWEAK is a member of the tumor necrosis factor superfamily. The interaction of TWEAK with its receptor Fn14 regulates multiple cellular responses, including stimulation of proliferation, migration, apoptosis, angiogenesis, and induction of proinflammatory cytokines. This paper reports for the first time the molecular cloning of dog TWEAK and Fn14. The open reading frame (ORF) of dog TWEAK is 750bp, its genomic DNA consists of seven exons and six introns and is approximately 10kb in size by computer-assisted analysis. Sequence similarity at the amino acid level between dog TWEAK and human or mouse was 95 and 92%, respectively. The ORF of dog Fn14 contains 390bp. Sequence similarity at the amino acid level between dog Fn14 and human, or mouse, or frog was 95, 93 and 64%, respectively. Real-time quantitative PCR analysis revealed that both TWEAK and Fn14 are constitutively expressed in various tissues in dog. Furthermore, we verified dTWEAK interacted with dFn14 by yeast two-hybrid assay. Our results suggest that the TWEAK-Fn14 pathway is evolutionarily highly conserved. It will be helpful for investigation on the biological role of the TWEAK/Fn14 system in this important animal model. Furthermore, it provides insight into the molecular evolution of the emerging TWEAK and Fn14 families.