Characterization of primary structure and tissue expression profile of the chicken apical sodium-dependent bile acid transporter mRNA

• Published in: Poultry science Vol. 94; no. 4; pp. 722 - 727
• Main Authors: Nakao, N., Kaneda, H., Tsushima, N., Ohta, Y., Tanaka, M.
• Format: Journal Article
• Language: English
• Published: England Poultry Science Association, Inc 01.04.2015
• Subjects: Amino Acid Sequence; Animals; Avian Proteins - genetics; Avian Proteins - metabolism; Base Sequence; Chickens - genetics; Chickens - metabolism; Female; Molecular Sequence Data; Organ Specificity; Organic Anion Transporters, Sodium-Dependent - genetics; Organic Anion Transporters, Sodium-Dependent - metabolism; Real-Time Polymerase Chain Reaction - veterinary; RNA, Messenger - genetics; RNA, Messenger - metabolism; Symporters - genetics; Symporters - metabolism; chicken; intestine; expression; bile acids; ASBT mRNA
• ISSN: 0032-5791; 1525-3171
• DOI: 10.3382/ps/pev027

The ileal apical sodium-dependent bile acid cotransporter (ASBT) plays an essential role in the absorption of bile acids from intestinal lumina. ASBT cDNA has been cloned from mammalian and fish species, and the primary structure of the protein and expression properties of the mRNA have been characterized. In this study, we identified chicken ASBT mRNA by cDNA cloning. Chicken ASBT cDNA consisted of 91 bp of the 5′-untranslated region, 1,083 bp of the coding region, and 1,896 bp of the 3′-untranslated region. The cDNA encoded a protein of 360 amino acids showing significant sequence identity with mammalian and fish ASBT. The amino acid residues known to participate in the functions of mammalian ASBT were conserved in chicken ASBT. Real-time polymerase chain reaction analysis revealed that chicken ASBT mRNA was expressed at markedly higher levels in the ileum and proximal colon/rectum, relatively lower levels in the kidney, and very low levels in the jejunum and cecum. Expression levels in the ileum markedly increased after hatching, reached the highest levels on day 7 posthatching, and then decreased to adult levels. A similar expression pattern was observed in the proximal colon/rectum except for the significant decrease from day 7 posthatching to day 21 posthatching. These results suggest that chicken ASBT functions as a bile acid transporter in the ileum and proximal colon/rectum, particularly during the early posthatching period.