Cloning, expression and tissue distribution of IGF-1 from giant panda ( Ailuropoda melanoleuca )

Insulin-like growth factor-1 (IGF-1) is a polypeptide that regulate growth, differentiation and muscle regeneration in several species. This study was designed to analyse the cDNA sequence of IGF-1 in giant panda, its gene expression and tissue distributions in relation to growth, development and reproduction of captive giant pandas. A cDNA encoding IGF-1 was cloned by reverse transcriptase-PCR from a male giant panda cub liver tissue. Sequence alignment analysis showed the cysteine residues and other amino acid residues of the mature IGF-1 peptide of giant panda are highly conserved in mammalian species. DNA encoding the mature IGF-1 peptide of the giant panda was ligated with pET-DsbA expression vector and expressed in E. coli BL21. Western blot confirmed the IGF-1 antigen activity of the recombinant protein. By in situ hybridization and immunohistochemistry analysis it is demonstrated that the IGF-1 mRNA distribution abundance were significantly higher in the liver, muscles and heart than those in the other tissues studied. However, the IGF-1 peptide distribution abundances in all the tissues studied did not show any significant differences. The localization of the IGF-1 peptide was in accordance with that of mRNA for each tissue. These results may suggest that IGF-1 play an autocrine or paracrine role in regulation of the giant panda growth and development.