Leptin in Darkbarbel Catfish Pseudobagrus vachellii: Molecular Characterization, Synteny and Phylogeny, Tissue Distribution, and Expression in Response to Different Feeding Status.

Leptin is a small peptide secreted by adipocytes and it plays important roles in regulating appetite, energy homeostasis, bodyweight, reproduction and immunity. However, its roles are still limited in teleosts. In the present study, a leptin gene was characterized from the darkbarbel catfish (Pseudobagrus vachellii) and its expression patterns in response to different feeding status were investigated. The cDNA of the pvleptin was 1186 bp long, containing a 519 bp open reading frame (ORF) that predicted to encode a protein of 172 amino acids. Multiple Leptins alignment showed that four a-helix domains and two cysteine residues were conserved in vertebrates. Three-dimensional (3D) structure modeling revealed that pvLeptin was highly conserved with that of other tetrapods. Genetic synteny analysis revealed that lepB had specifically lost in siluriformes teleosts. Phylogenetic analysis showed that fish lineage contained two clades of leptinA and leptinB, and the pvleptin was grouped into leptinA clade and shared a close relationship with its counterpart in P. fulvidraco. Tissue distribution analysis showed that pvleptin was widely distributed with the highest mRNA expression level in liver. Two-week fasting significantly decreased the transcription level while refeeding elevated the mRNA expression level of pvleptin in liver, suggesting leptin may be involved in regulating food intake and energy metabolism in darkbarbel catfish. These findings may expand our understanding about the evolutionary history and functional roles of Leptin in teleost, as well as lay a solid foundation for commercial production of darkbarbel catfish. [ABSTRACT FROM AUTHOR]