Leptin-A Tilapia

In tilapia (Oreochromis niloticus), two leptin sequences, tLepA and tLepB, along with one leptin receptor sequence (tLepR), have been identified . The full-length cDNA of tLepR encodes a protein of 1140 amino acids, containing all functionally important domains conserved among vertebrate leptin receptors . The cDNAs of tLepA and tLepB encode proteins of 161 and 152 amino acids, respectively .

Recombinant Leptin-A Tilapia (rtLepA) is produced in Escherichia coli as a single, non-glycosylated polypeptide chain containing 161 amino acids, with a molecular mass of 16,491 Daltons . The recombinant protein is purified using proprietary chromatographic techniques .

Leptin-A in tilapia has been shown to regulate various biological processes. For instance, it stimulates cellular glycolysis through a STAT3-dependent mechanism . Transcriptomic analysis of prolactin cells in the tilapia pituitary revealed that rtLepA differentially regulates 1,995 genes, influencing numerous cellular gene networks, including metabolism, protein processing, transport, and cell cycle . Leptin-A also stimulates the expression of glycolytic enzymes such as glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and 6-phosphofructo-1-kinase (PFK1), enhancing glycolytic output .

Recombinant Leptin-A Tilapia is biologically active in promoting the proliferation of BAF/3 cells stably transfected with the long form of the human leptin receptor, although its activity is lower than that of mammalian leptin . It is also active in promoting STAT-LUC activation in COS7 cells transfected with the tilapia leptin receptor .

For practical applications, the lyophilized form of Leptin-A Tilapia is stable at room temperature for three weeks but should be stored desiccated below -18°C for long-term storage . Upon reconstitution, it should be stored at 4°C for short-term use and below -18°C for future use, with the addition of a carrier protein to prevent freeze-thaw cycles .