Molecular Cloning, Characterization, and mRNA Expression of Intestinal Fatty Acid Binding Protein (I-FABP) in Columba Livia

Intestinal fatty acid binding protein (I-FABP) is involved in fatty acid transportation in mammals. To verify its role in fatty acid metabolism in birds, the model of pigeon intestinal organ culture was established, and a full-length cDNA of I-FABP was cloned from the intestine of Columba livia by rapid amplification of cDNA ends (RACE) method for the first time. The full length cDNA of C. livia I-FABP was 855 bp, including a 5′untranslated region (UTR) of 34 bp, a 3′UTR of 422 bp and an open reading frame (ORF) of 399 bp encoding a protein of 132 amino acids with the predicted molecular weight of 15.13 kDa. Sequence comparison indicated that I-FABP of C. livia had high identity with other avian I-FABP and belonged to the first subfamily of FABPs. Using quantitative real-time PCR, pigeon I-FABP mRNA in duodenum and jejunum increased progressively with development stage. I-FABP mRNA was expressed at the highest level at 28 day post hatch in the duodenum, while in ileum, it reached the maximum at the day of hatch, and decreased subsequently. The effects of fatty acids on pigeon I-FABP expression were also investigated in vitro. The results showed that significant increases in the pigeon I-FABP mRNA level were induced by linoleic acid and arachidonic acid, whereas I-FABP gene expression appeared to be unaffected by oleic acid and αlinolenic acid. The results indicate that I-FABP may be indicative of intestine development in pigeon, and it could be regulated by n-6 polyunsaturated fatty acids.