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Short‐term Regulation of Amino Acid Transporters by Amino Acids
Author(s) -
Jando Julia,
Jordi Josua,
Verrey François
Publication year - 2015
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.29.1_supplement.969.3
Subject(s) - transporter , efflux , amino acid transporter , amino acid , chemistry , brush border , in vivo , homeostasis , blot , epithelial polarity , small intestine , ex vivo , biochemistry , medicine , endocrinology , biology , in vitro , cell , membrane , gene , vesicle , microbiology and biotechnology
To ensure body homeostasis amino acids (AA) are (re)absorbed by epithelial cells of the intestinal mucosa and renal proximal tubules. This sequential transepithelial transport includes an apical uptake followed by a basolateral efflux. The luminal uptake is mediated by different AA transporters but most neutral AAs are transported by the luminal Broad neutral Amino acid Transporter B 0 AT1 (SLC6A19). The regulation of this transporter is poorly known; in particular its potential short‐term regulation by its substrates has not been investigated. We hypothesized that similarly to glucose transporters the expression of B 0 AT1 might be repressed if costs of its synthesis and expression exceed its benefits and thus it would be upregulated by AAs to absorb them efficiently when available. To investigate the possible short‐term regulation of B 0 AT1 by AAs in vivo, we assessed in rats whether after a fast of 4 or 16 hours, intragastric AA application upregulates B 0 AT1 expression in intestinal brush border membranes. The time point of analysis after amino acid gavage was determined based on micro Computer Tomography measurements showing when the AA mix reached the small intestine. However, functional analysis of AA absorption in isolated ex vivo intestinal rings showed no significant difference between rats having received a water or an AA gavage. In addition, protein expression levels of B 0 AT1 in the intestinal brush border analyzed by Western blotting did not reveal a difference between rats having received a water or AA gavage. In conclusion, in the selected experimental conditions, the expression and function of the apical AA transporter B 0 AT1 was not regulated in the short‐term by the preceding application of its substrate AAs. Supported by the Swiss National Science Foundation.