Genomic characterization and tissue distribution of leptin receptor and leptin receptor overlapping transcript genes in the pufferfish, Takifugu rubripes

Full-length cDNAs encoding the leptin receptor (tfLEPR), leptin receptor overlapping transcript (tfLEPROT) and leptin receptor overlapping transcript-like 1 (tfLEPROTL1) were cloned and sequenced from the pufferfish, Takifugu rubripes. The tfLEPR gene encoded an 1116-amino acid protein that includes almost all functionally important domains conserved among vertebrate LEPR such as three fibronectin type III domains, the immunoglobulin (Ig) C2-like domain and a pair of repeated tryptophan/serine motifs. The tfLEPR mRNA was abundantly expressed in the pituitary and ovary and moderately expressed in brain, eye, heart, kidney, liver and testis. Both tfLEPROT and tfLEPROTL1 genes encoded a 130-amino acid protein. Human LEPR gene shares the first and second exons with the LEPROT gene, and they are continuously located on chromosome 1p31. In contrast, Takifugu LEPR and LEPROT were located at different regions of the chromosome. However, both Takifugu regions showed genomic synteny with the human genome around LEPR gene on chromosome 1p31. This result could mean that the Takifugu chromosomes around LEPR and LEPROT genes are paralogous genomic regions derived from genome duplication early in the teleost lineage and the overlapping LEPR and LEPROT genes were subsequently lost.