Molecular cloning, characterization and expression analysis of multiple leptin genes in Jian carp (Cyprinus carpio var. Jian)

Three leptin genes (jlLEP-A1, jlLEP-A2 and jlLEP-B) were cloned and characterized in Jian carp (Cyprinus carpio var. Jian), with a highly conserved organization encoded by two exons and one intron. jlLEP-A1 and jlLEP-A2 contained 93 and 102 bp introns, respectively, encoding a 171-amino acid protein. jlLEP-B contained a 687 bp intron encoding a 168-aa protein. jlLEP-A1 and jlLEP-A2 shared 82.5% identity, but only 29.2% and 28.6% with jlLEP-B, respectively. jlLEP-A1, jlLEP-A2, and jlLEP-B were expressed in a wide range of tissues, but the expression pattern differed between juveniles and adults (and females and males). In juveniles, the expression of jlLEP-A1 and jlLEP-B was higher than jlLEP-A2, and was the highest in the liver and gonad. In females, jlLEP-A1 and jlLEP-A2 expression was the highest in the hypothalamus and liver, whereas jlLEP-B mRNA was detected at low levels in all tissues. In males, jlLEP-A1 mRNA was expressed primarily in the hypothalamus, with only very low levels in the peripheral tissues. jlLEP-A2 and jlLEP-B mRNA were primarily expressed in the muscle, hypothalamus, and liver. The expression of jlLEP-A1 and jlLEP-B mRNA was high in the ovary and testis, respectively. Our results suggest that leptins play an important physiological role in reproduction.