Signaling pathways involved in tumor necrosis factor alpha-induced upregulation of the taurine transporter in Caco-2 cells.

We have previously demonstrated that the taurine uptake and transporter (TAUT) mRNA expression were upregulated by tumor necrosis factor alpha (TNF-alpha) in Caco-2 cells. In this present study, the signaling molecules related to this upregulation were investigated. Pyrrolidine dithiocarbamate, a nuclear factor kappaB (NF-kappaB) inhibitor, repressed the upregulation of taurine uptake and TAUT mRNA expression. A reporter assay revealed that TNF-alpha-induced TAUT transcriptional activity through the NF-kappaB consensus-like sequence in the human TAUT promoter region. An electrophoretic mobility shift assay showed that NF-kappaB could bind to the NF-kappaB consensus-like sequence. The anti-TNF receptor 1 (TNFR1) antibody, but not the TNF receptor 2 (TNFR2) antibody, repressed this upregulation.