Genomic structure and promoter analysis of the bovine leptin gene.

The product of the leptin gene is a 16-kDa protein secreted by adipose tissue and regulates adiposity. The leptin gene could be a potential candidate gene controlling some proportion of adipose and lean accretion in cattle, and thus, may be referred to as one of genetic factor controlling meat quality determinants such as marbling. We have isolated the bovine leptin gene including its promoter region. We have determined the exon-intron organization of the bovine leptin gene, which consisted of three exons and two introns and spanned about 18.9 kb, equivalent to that of human or mouse gene. A approximately 3-kb 5'-flanking region upstream from the putative transcription start site of the gene contained consensus Sp1 and CCAAT/enhancer-binding protein (C/EBP) motifs, and transient transfection assay with secreted alkaline phosphatase reporter confirmed the promoter activity in 3T3-L1 cells that possessed expression of the cotransfected C/EBP alpha expression plasmid. Cotransfection with C/EBP alpha caused 24-fold activation in leptin reporter expression, as compared to cotransfection with control plasmid, consistent with existence of the putative C/EBP alpha binding site in the proximal 5'-flanking region of the bovine leptin gene.