Dioxin responsive element

Lai, Z., Pineau, T., and Esser, C., Identification of dioxin-responsive elements (DREs) in the 5 regions of putative dioxin-inducible genes, Chemico-Biological Interact., 100, 97, 1996. 

Sulentic, C., et. al., Interactions at a dioxin responsive element (DRE) and an overlapping kappaB site within the hs4 domain of the 3 alpha immunoglobulin heavy chain enhancer, Toxicology, 200, 235, 2004. 

Several overall conclusions can be drawn based on the statistical evaluation of the data submitted by the participants of the DR CALUX intra-and interlaboratory validation study. First, differences in expertise between the laboratories are apparent based on the results for the calibration curves (both for the curves as provided by the coordinator and for the curves that were prepared by the participants) and on the differences in individual measurement variability. Second, the average results, over all participants, are very close to the true concentration, expressed in DR CALUX 2,3,7,8-TCDD TEQs for the analytical samples. Furthermore, the interlaboratory variation for the different sample types can be regarded as estimates for the method variability. The analytical method variability is estimated to be 10.5% for analytical samples and 22.0% for sediment extracts. Finally, responses appear dependent on the dilution of the final solution to be measured. This is hypothesized to be due to differences in dose-effect curves for different dioxin responsive element-active substances. For 2,3,7,8-TCDD, this effect is not observed. Overall, based on bioassay characteristics presented here and harmonized quality criteria published elsewhere (Behnisch et al., 2001a), the DR CALUX bioassay is regarded as an accurate and reliable tool for intensive monitoring of coastal sediments. 

Figure 9.9 Interaction of the Ah-receptor-ligand complex with the 5 flanking region of the P450 1A1 gene. Two dioxin responsive elements (DREs) appear to lie approximately 1000 or more base pairs upstream from the 1A1 transcriptional s tart site. These elements appear to be transcriptional enhancers, whereas less direct evidence indicates an inhibitory element ( negative control element ) between 400 and 800 bases upstream. The negative control element may inhibit the 1A1 promoted although the conditions for this inhibition are, as yet, undefined. (Adapted from A. B. Okey, Pharmacol. Ther. 45 241-298, 1990.)...

Fig. 5.1 Principle behind the CALUX bioassay for Ah-receptor agonists. Following binding of the agonist to the Ah-receptor, the complex will be transported to the nucleus and bind to a so-called dioxin responsive element, resulting in the increased transcription of the luciferase gene and production of luciferase. Following incubation this enzyme can subsequently be measured in cell lysates by a light producing reaction.

Figure 32.6. Model of AhR-mediated mechanism of action of TCDD and related HAHs. TCDD binds to the AhR in the cytoplasm. This complex interacts with another cytosolic protein (ARNT) and is translocated into the nucleus where it binds to specific DNA enhancer sequences upstream of TCDD responsive genes. Exactly which genes are important in the resulting immune suppression is unclear. Abbreviations AhR, aryl hydrocarbon receptor ARNT, AhR nuclear transporter DRE, dioxin-responsive elements.

DRE Dehydratiou respouse element dioxin response element... 

Abbreviations used in text AA, arachidonic acid AhR, aryl hydrocarbon receptor Amt, AhR nuclear translocator BR, bilirubin BV, biliverdin CYP1A1, cytochrome P4501A1 DRE, dioxin responsive element FICZ, 6-formylindolo(3,2b)carbazole HAH, halogenated aromatic hydrocarbon I3C, indole 3-carbinol ICZ, indolo-(3,2,-b)-carbazole PAH, polycyclic aromatic hydrocarbon RAR, retinoic acid receptor TCDD, 2,3,7,8-tetrachlorodi benzo-/>-dioxin Trp, tryptophan UGT 01, UDP-glucuronosy 1 transferase 01... 

Sun YV, Boverhof DR, Burgoon LD, Fielden MR, Zacharewski TR. Comparative analysis of dioxin response elements in human, mouse and rat genomic sequences. Nucleic Acids Res 2004 32 4512-23. 

In 2005, the Ministry of the Environment of Japan evaluated four novel simple bioassays for monitoring dioxin contamination in effluent gas, fly ash, and cinders. In the CALUX assay, recombinant mouse hepatoma cells (HlL6.1c2) with four dioxin-responsive elements upstream of the luciferase gene are treated with extracts from contaminated samples, and the luciferase activity is then measured [2]. Luciferase activity induced in the recombinant human hepatoma cell line lOlL and the recombinant mouse hepatoma cell line HeB5 is utilized in the P450 Human Reporter Gene System (HRGS) and Ah luciferase assays, respectively [3]. 

Fig. 5 Generic mechanism of AhR-mediated toxicity AhR mediates signal transduction by dioxin-like ligands, which form a transcription factor complex with an aryl hydrocarbon nuclear translocator protein (ARNT). This heterodimer recognizes specific DNA sequences, namely dioxin responsive elements (DREs), and leads to induction of several genes forming the so-called Ah gene battery. In this process, the elevated levels of the protein products are assumed to be involved in the toxic action of AhR ligands. AIP AhR inhibitory protein, hsp90 90-kDa heat shock protein, ARNT AhR nuclear translocator, XRE xenobiotic response element, CYPIA eyto-chrome P450 lA gene/protein (adapted from [211, 212])...

Nukaya M, Moran S, Bradfield CA (2009) The role of the dioxin-responsive element cluster between the Cyplal and Cypla2 loci in aryl hydrocarbon receptor biology. Proc Natl Acad Sci U S A 106 4923-4928... 

The rat hepatic cytosol fraction was prepared as described previously (7). The cytosol fraction (4.0 mg/ml protein) was incubated with various concentrations of green tea extracts 10 min prior to addition of 1 nM TCDD (AccuStandard, New Heaven, CT, USA) at 20°C for 2 h to lead transformation of AhR. Transformed AhR was detected by electrophoretic mobility shift assay (EMSA) using a P-labeled dioxin responsive element (DRE) oligonucleotide probe as described previously (7). 

---