Induction of translationally controlled tumor protein (TCTP) by transcriptional and post-transcriptional mechanisms.
Expression of the human TPT1 gene coding for translationally controlled tumor protein (TCTP) was investigated in Calu-6 and Cos-7 cells under the influence of 4beta-phorbol 12-myristate 13-acetate (PMA), forskolin, dioxin and the heavy metals copper, nickel and cobalt. Transcriptional and post-transcriptional aspects of the mechanism were analyzed by TCTP mRNA/protein quantification, luciferase reporter gene assays depending on TPT1 promoter sequences or TCTP mRNA 5'/3'-UTRs and investigation of the interaction of RNA-binding proteins with UTRs by UV-crosslinking. PMA, forskolin, dioxin, cobalt and nickel induced TCTP expression in 24 h in both cell lines about 2.2-3.2-fold at the mRNA level and 1.6-2.2-fold at the protein level. The highest induction rate, 4.5-5.0-fold at the mRNA level and 3.5-4.0-fold at the protein level, was observed with copper. TPT1 promoter assays showed transcriptional activation by PMA, forskolin and dioxin (2.0-3.1-fold) and a 7.0-8.0-fold increase by copper, whereas cobalt and nickel had no effect. Deletion analysis revealed that copper-dependent transcriptional control was transmitted by a metal-responsive element residing in the TPT1 promoter. Post-transcriptional activation of TCTP expression was associated with the action of dioxin, nickel, cobalt (1.8-2.3-fold) and copper (2.5-3.0-fold), whereas stimulation of TCTP synthesis by copper was mediated by the TCTP mRNA 3'-UTR (3.2-fold) but not by the 5'-UTR (0.5-fold). mRNA stabilization was found to mediate these effects of cobalt and nickel. Post-transcriptional regulation was associated with qualitative and quantitative changes in the binding of specific RNA-binding proteins to UTRs.
Schmidt
Irina
I
Charité, Universitätsmedizin Berlin, Institut für Vegetative Physiologie, Germany.
Fähling
Michael
M
Nafz
Benno
B
Skalweit
Angela
A
Thiele
Bernd-Joachim
BJ
D024509:3' Flanking Region; D000818:Animals; D001665:Binding Sites; D014408:Biomarkers, Tumor / Q000235:genetics* / Q000378:metabolism*; D015152:Blotting, Northern; D015153:Blotting, Western; D019556:COS Cells; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003035:Cobalt / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D003300:Copper / Q000494:pharmacology; D004147:Dioxins / Q000494:pharmacology; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D009532:Nickel / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000235:genetics; D014176:Protein Biosynthesis; D020218:Response Elements; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D000090324:Tumor Protein, Translationally-Controlled 1
D014408:Biomarkers, Tumor; D004147:Dioxins; C000715647:TPT1 protein, human; D000090324:Tumor Protein, Translationally-Controlled 1; D005576:Colforsin; D003035:Cobalt; D003300:Copper; D009532:Nickel; D008156:Luciferases; D013755:Tetradecanoylphorbol Acetate