Existence of leptin receptor protein in chicken tissues: Isolation of a monoclonal antibody against chicken leptin receptor

Leptin receptor belongs to the class I cytokine receptor superfamily, which mediates multiple physiological roles in mammals. However, the leptin system is poorly understood in birds, as the evidence for the existence of a natural ligand of the receptor in birds is controversial. As part of a strategy to reveal the physiological significance of leptin in birds, we isolated a monoclonal antibody (mAb) against a chicken leptin receptor (chLEPR). Based on the cDNA sequence for chLEPR, a peptide coding for the cytoplasmic domain of chLEPR was expressed in Escherichia coli and this was used to immunize mice to obtain the mAb. The anti-chLEPR mAb recognized proteins migrated at approximately 180 kDa by Western blot analysis using cellular extracts prepared from COS-7 cells transfected with chLEPR expression vector. By Western blot analysis using the same mAb, an immunoreactive band migrated at 180 kDa was detected in the chicken brain and Leghorn male hepatoma (LMH) cells, and which was similar to the size observed in the in vitro transfection study. Taken together, the chLEPR mAb obtained in the present study cross-reacted, at least, with long isoform chLEPR, suggesting that LEPR mRNA expressed in chicken tissues is likely to be translated. The chLEPR mAb, which has not been described elsewhere, enables us to explore the expression and localization of the receptor in the chicken tissues at the protein level. Therefore, this antibody would be a powerful tool in studying and understanding the regulation and function of leptin and its receptors in birds.