Partial cloning and expression of the bovine leptin gene.

The product of the leptin (i.e., obese) gene may be an important regulator of energy metabolism, adiposity, and reproduction, and is perhaps linked to meat quality determinants such as marbling. Molecular probes were developed using polymerase chain reaction (PCR) technology to evaluate leptin expression in adipose depots and to evaluate the tissue-dependent nature of expression reported in other species. A 438 bp fragment representing the coding region of the bovine leptin gene excluding the N-terminal secretory signal was amplified, cloned into a plasmid vector (pASK75), and expressed in E. coli. Sequence analysis of the cDNA and the corresponding polypeptide indicate that, overall, both share approximately 87% homology with the mouse and human leptin genes and polypeptides. Amino terminal sequencing (30 amino acid residues) of the recombinant bovine leptin (rBL) protein revealed 100% homology with mouse and human leptin. The bovine leptin gene is expressed as a 3,090 nt mRNA which is detected in adipose tissue, but is not found in brain (despite the appreciable fat content and lipid metabolism) or other tissues. Leptin gene expression in several adipose depots (subcutaneous, renal, and omental) was similar (P = .73) in finished cattle.