Gene organization, alternate splicing and expression pattern of porcine visfatin gene.

Visfatin is a newly discovered visceral fat-specific adipocytokine. It is upregulated in obesity and exerts insulin-mimetic effects in various tissues in human and mouse. We reported here the cloning and characterization of porcine visfatin, its three alternate splicing variants. Sequence analysis indicated that variant 1 is the predominant form among species, which contains an open reading frame of 1473 bp encoding a 52-kDa protein of 491 amino acids. While the other two variants were predicted to encode two 3' truncated proteins due to early termination. The nucleotide and amino acid sequences deduced from variant 1 were conservative across species. The porcine visfatin gene was composed of 11 exons at least and had exactly the same exon/intron structure as the human orthologs. Nested PCR showed that variants 1 and 3 were ubiquitously expressed in porcine tissues and that variant 2 was expressed in most tissues examined with exception of testis and liver. The discovery of the three variants of visfatin in porcine would be useful to the further investigation of the function of the visfatin gene.