Taurine modulates expression of transporters in rat brain and heart

In pro- and eucaryotic life, cellular and subcellular compartments are sepa rated by membranes and the regulated and selective passage of specific mole cules across these membranes is a basic and highly conserved principle. We were interested whether taurine, a naturally occuring amino acid, would be able to induce or suppress expression of transporters with the Rationale that taurine was shown to detoxify a series of endogenous toxins and xenob iotics of various chemically non-related structures. For this purpose we used a gene hunting technique, subtractive hybridizatio n, subtracting mRNAs of taurine-treated rat brain and heart from untreated controls. Subtracted mRNAs were then converted to cDNAs, amplified, sequenc ed and identified by gene bank data. We found five transporter transcripts, the phosphonate transport ATPase PHN C, multidrug transporter homolog MTH104, protein-export-membrane protein SE CD, oligopeptide transporters oppA and oppD, in the brain and two: ABC-tran sporter BRAF-2 and cation-transport ATPase PACS, in the heart. Homologies o f the sequences found were in any case >50% thus permitting the identificat ion of transporters with high probability. The biological meaning could be that a naturally occuring amino acid, tauri ne, modulates complex transport systems. The most prominent finding is the upregulation of a multidrug transporter transcript, explaining a mechanism for the nonselective detoxifying action of taurine.