Taurine uptake across the human intestinal brush-border membrane is via two transporters: H+-coupled PAT1 (SLC36A1) and Na+- and Cl−-dependent TauT (SLC6A6)
Author(s)
Anderson, CMH
Howard, A
Walters, JRF
Ganapathy, V
Thwaites, DT
Type
Journal Article
Abstract
Taurine is an essential amino acid in some mammals and is conditionally essential in humans. Taurine is an abundant component of meat and fish-based foods and has been used as an oral supplement in the treatment of disorders such as cystic fibrosis and hypertension. The purpose of this investigation was to identity the relative contributions of the solute transporters involved in taurine uptake across the luminal membrane of human enterocytes. Distinct transport characteristics were revealed following expression of the candidate solute transporters in Xenopus laevis oocytes: PAT1 (SLC36A1) is a H+-coupled, pH-dependent, Na+- and Cl−-independent, low-affinity, high-capacity transporter for taurine and β-alanine; TauT (SLC6A6) is a Na+- and Cl−-dependent, high-affinity, low-capacity transporter of taurine and β-alanine; ATB0,+ (SLC6A14) is a Na+- and Cl−-dependent, high-affinity, low-capacity transporter which accepts β-alanine but not taurine. Taurine uptake across the brush-border membrane of human intestinal Caco-2 cell monolayers showed characteristics of both PAT1- and TauT-mediated transport. Under physiological conditions, Cl−-dependent TauT-mediated uptake predominates at low taurine concentrations, whereas at higher concentrations typical of diet, Cl−-independent PAT1-mediated uptake is the major absorptive mechanism. Real-time PCR analysis of human duodenal and ileal biopsy samples demonstrates that PAT1, TauT and ATB0,+ mRNA are expressed in each tissue but to varying degrees. In conclusion, this study is the first to demonstrate both taurine uptake via PAT1 and functional coexpression of PAT1 and TauT at the apical membrane of the human intestinal epithelium. PAT1 may be responsible for bulk taurine uptake during a meal whereas TauT may be important for taurine supply to the intestinal epithelium and for taurine capture between meals.
Date Issued
2009-05-15
Date Acceptance
2009-05-15
Citation
Journal of Physiology, 2009, 587 (4), pp.731-744
ISSN
0022-3751
Publisher
Wiley
Start Page
731
End Page
744
Journal / Book Title
Journal of Physiology
Volume
587
Issue
4
Copyright Statement
© 2009 The Authors. Journal compilation © 2009 The Physiological Society.
Subjects
Science & Technology
Life Sciences & Biomedicine
Neurosciences
Physiology
Neurosciences & Neurology
NEUROSCIENCES
PHYSIOLOGY
CACO-2 CELL MONOLAYERS
RAT SMALL-INTESTINE
AMINO-ACID
BETA-ALANINE
FUNCTIONAL-CHARACTERIZATION
ACTIVE-TRANSPORT
RABBIT ILEUM
LINE CACO-2
BILE-ACIDS
EXPRESSION
Amino Acid Transport Systems
Animals
Caco-2 Cells
Female
Humans
Hydrogen
Intestinal Mucosa
Intestine, Small
Membrane Glycoproteins
Membrane Transport Proteins
Microvilli
Symporters
Taurine
Xenopus laevis
06 Biological Sciences
11 Medical And Health Sciences
Publication Status
Published