Substrate upregulation of the human small intestinal peptide transporter, hPepT1

• DOI: 10.1111/j.1469-7793.1998.697bs.x
• Publication Date: 2004-09-22T09:53:43Z
• Authors: Dianne Walker; David T. Thwaites; Nicholas L. Simmons; Harry J. Gilbert; Barry H. Hirst
• Keywords: 0301 basic medicine; Symporters; Transcription, Genetic; Cell Membrane; Immunoblotting; Biological Transport; Dipeptides; Adenocarcinoma; Peptide Transporter 1; Recombinant Proteins; Cell Line; Kinetics; 03 medical and health sciences; Amino Acid Substitution; Gene Expression Regulation; Colonic Neoplasms; Intestine, Small; Humans; RNA, Messenger; Cloning, Molecular; Carrier Proteins

Molecular mechanisms underlying physiological adaptation to increased levels of dietary peptides have been elucidated by studying the response substrate glycyl‐L‐glutamine (Gly‐Gln) proton‐coupled peptide transporter, hPepT1, in Caco‐2 human intestinal cell line. V max for apical uptake [ 14 C]glycyl‐[ C]sarcosine was 1.64 (± 0.34)‐fold after incubation cells 3 days a peptide‐rich medium (4 mM Gly‐Gln replacing 4 Gln). A full‐length hPepT1 cDNA clone identical small with exception single amino acid substitution Ile‐662 Val. Transcript sizes, on Northern blots poly(A) + RNA probed 630 bp 5′ probe, correspond reported band pattern seen RNA. The dipeptide‐induced increase transport accompanied parallel 1.92 0.30)‐fold ( n = 9 ) mRNA. This part due an mRNA half‐life from 8.9 ± 1.1 12.5 1.6 h ), but does not account fully observed levels, suggesting that there also dipeptide‐mediated transcription. Anti‐hPepT1‐specific antipeptide antibodies localized exclusively membrane enterocytes and cells. supplementation media resulted 1.72 0.26)‐fold 5 staining intensity We conclude provide appropriate model study at molecular level, peptide. magnitude functional activity can be accounted protein mRNA, latter mediated both enhanced stability signalling pathway between upregulation, therefore, involves direct action enterocyte, independent hormonal and/or neural control.