Isolation, sequence analysis and expression profile of a novel porcine gene, CXCL10, differentially expressed in the Longissimus dorsi muscle tissues from Meishan, Meishan x Large White cross and Large White pigs.

In order to detect the molecular mechanism of heterosis in pigs, the mRNA differential display (DD) technique was performed to investigate the differences in gene expression in the Longissimus dorsi muscle tissues from Meishan (MS), Meishan x Large White (ML) cross and Large White (LW) pigs. One novel gene that was differentially expressed was identified using semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) and its full-length cDNA sequence was obtained using the rapid amplification of cDNA ends (RACE) method. The nucleotide sequence of the gene is not homologous to any of the known porcine genes. The sequence prediction analysis revealed that the open reading frame of this gene encodes a protein of 104 amino acids that contains the putative conserved domain of the chemokine CXC which could be designated as chemokine cd00273 subgroup and this protein has high homology with the small inducible cytokine B10 precursor (CXCL10) of five species - dog(87%), human (84%), monkey (84%), mouse (75%) and rat (70%) - so that it can be defined as swine small inducible cytokine B10 precursor. The phylogenetic tree analysis revealed that the swine CXCL10 has a closer genetic relationship with the CXCL10 of dog than with those of human, monkey, mouse and rat. The tissue expression analysis indicated that the swine CXCL10 gene is more highly expressed in muscle and weakly expressed in fat and kidney. The genomic sequence of swine CXCL10 gene was finally amplified and result revealed that the swine CXCL10 gene contains four exons and three introns. Our experiment is the first to establish the primary foundation for further research on the swine CXCL10 gene.