title: Effect of taurine on mRNA expression of thioredoxin interacting protein in Caco-2 cells.
abstract: Taurine (2-aminoethanesulfonic acid), a sulfur-containing β-amino acid, plays an important role in several essential biological processes; although, the underlying mechanisms for these regulatory functions remain to be elucidated, especially at the genetic level. We investigated the effects of taurine on the gene expression profile in Caco-2 cells using DNA microarray. Taurine increased the mRNA expression of thioredoxin interacting protein (TXNIP), which is involved in various metabolisms and diseases. β-Alanine or γ-aminobutyric acid (GABA), which are structurally or functionally related to taurine, did not increase TXNIP mRNA expression. These suggest the expression of TXNIP mRNA is induced specifically by taurine. β-Alanine is also known to be a substrate of taurine transporter (TAUT) and competitively inhibits taurine uptake. Inhibition of taurine uptake by β-alanine eliminated the up-regulation of TXNIP, which suggests TAUT is involved in inducing TXNIP mRNA expression. The up-regulation of TXNIP mRNA expression by taurine was also observed at the protein level. Furthermore, taurine significantly increased TXNIP promoter activity. Our present study demonstrated the taurine-specific phenomenon of TXNIP up-regulation, which sheds light on the physiological function of taurine.
authors.affiliation: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Gondo
authors.forename: Hideo
authors.initials: H
authors.lastname: Satsu
authors.forename: Yoko
authors.initials: Y
authors.lastname: Ishimoto
authors.forename: Taku
authors.initials: T
authors.lastname: Iwamoto
authors.forename: Makoto
authors.initials: M
authors.lastname: Shimizu
mesh_terms: D024506:5' Flanking Region / Q000187:drug effects; D000596:Amino Acids / Q000494:pharmacology; D018938:Caco-2 Cells; D002352:Carrier Proteins / Q000235:genetics*; D015870:Gene Expression / Q000187:drug effects*; D020869:Gene Expression Profiling; D006801:Humans; D011401:Promoter Regions, Genetic / Q000187:drug effects; D012333:RNA, Messenger / Q000096:biosynthesis; D013654:Taurine / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects; D015854:Up-Regulation
chemical_list: D000596:Amino Acids; D002352:Carrier Proteins; D012333:RNA, Messenger; C486715:TXNIP protein, human; D013654:Taurine