The core promoter of human thioredoxin reductase 1: cloning, transcriptional activity, and Oct-1, Sp1, and Sp3 binding reveal a housekeeping-type promoter for the AU-rich element-regulated gene.
The selenoprotein thioredoxin reductase 1 (TrxR1) carries many vital antioxidant and redox regulatory functions. Its mRNA levels are known to be post-transcriptionally modulated via AUUUA motifs (AU-rich elements (AREs)), but the promoter yet remains unknown. Here we have cloned and determined the sequence of a 0.8-kilobase pair human genomic fragment containing the proximal promoter for TrxR1, which has transcriptional activity in several different cell types. The core promoter (-115 to +167) had an increased GC content and lacked TATA or CCAAT boxes. It contained a POU motif binding the Oct-1 transcription factor and two sites binding Sp1 and Sp3, which were identified with electrophoretic mobility shift assays using crude nuclear extracts of A549 cells. The TrxR1 promoter fulfills the typical criteria of a housekeeping gene. To our knowledge this is the first housekeeping-type promoter characterized for a gene with post-transcriptional regulation via ARE motifs generally possessed by transiently expressed proto-oncogenes, nuclear transcription factors, or cytokines and influencing mRNA stability in response to diverse exogenous factors. Expression of TrxR1 as an ARE-regulated housekeeping gene agrees with a role for the enzyme to maintain a balance between intracellular signaling via reactive oxygen species and protection of cells from excessive oxidative damage.
Rundlöf
A K
AK
Medical Nobel Institute for Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institute, SE-171 77 Stockholm, Sweden.
Carlsten
M
M
Arnér
E S
ES
D020816:Amino Acid Motifs; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D017931:DNA Primers / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D017930:Genes, Reporter; D006367:HeLa Cells; D051863:Host Cell Factor C1; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D008969:Molecular Sequence Data; D050811:Octamer Transcription Factor-1; D010084:Oxidation-Reduction; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction; D016329:Sp1 Transcription Factor / Q000378:metabolism; D051705:Sp3 Transcription Factor; D054481:Thioredoxin Reductase 1; D013880:Thioredoxin-Disulfide Reductase / Q000737:chemistry* / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured; D020298:U937 Cells
D017931:DNA Primers; D004268:DNA-Binding Proteins; C497692:HCFC1 protein, human; D051863:Host Cell Factor C1; D050811:Octamer Transcription Factor-1; C494165:POU2F1 protein, human; D012333:RNA, Messenger; C497121:SP3 protein, human; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; D051705:Sp3 Transcription Factor; D008156:Luciferases; C516124:TXNRD1 protein, human; D054481:Thioredoxin Reductase 1; D013880:Thioredoxin-Disulfide Reductase