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Basolateral Amino Acid Transport investigated using MDCK Epithelia and Mouse Models
Author(s) -
Guetg Adriano,
Torrente Marta,
Mariotta Luca,
Camargo Simone M.R.,
Verrey François
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.1210.21
Subject(s) - epithelial polarity , paracellular transport , amino acid , efflux , transcellular , transporter , antiporter , chemistry , proximal tubule , intracellular , kidney , microbiology and biotechnology , apical membrane , small intestine , biochemistry , function (biology) , brush border , in vivo , biology , cell , endocrinology , gene , membrane , genetics , vesicle , permeability (electromagnetism)
Amino acids (AAs) are (re)absorbed from the small intestine and the kidney proximal tubule epithelia via specific luminal and basolateral AA transporters (AATs). The basolateral exit step of this transcellular transport is less well understood than the luminal uptake. In particular, the cooperative role of the neutral AA antiporter LAT2 (SLC7A8) and that of the two uniporters TAT1 (SLC16A10) and LAT4 (SLC43A2) that transport aromatic AAs and β‐branched AAs respectively needs to be clarified. To investigate this issue we reconstituted the major transepithelial transport machinery for neutral amino acids in Madin‐Darby Canine Kidney (MDCK) cells to test its function. Measurements of intracellular AA showed that the additional expression of TAT1 in cells expressing LAT2 resulted not only in an increase of the basolateral efflux of TAT1 substrates but also of all other LAT2 AA substrates supporting the hypothesis that TAT1 enhances LAT2 function by recycling its exchange substrates. Furthermore, to investigate the role of LAT4 in vivo we determined its protein localization and characterized Lat4 −/− knock‐out (KO) mice. We detected LAT4 in kidney proximal tubule and thick ascending limb epithelial cells as well as in the enterocytes of small intestine villi. Interestingly, Lat4−/− KO mouse has a lethal phenotype pointing to an important physiological role of LAT4. Supported by Swiss NSF grant 31–130471 to FV.