Human cysteine dioxygenase type I (CDO-I; EC 1.13.11.20): 5' flanking region and intron-exon structure of the gene

AIM

The elucidation of the structure of the 5' flanking region and the exonic organisation of the human cysteine dioxygenase type I gene.

METHODS

Material for sequence studies was generated by polymerase chain reaction (PCR) methods using human genomic DNA, a cosmid clone containing the entire gene, and a commercial gene walking kit.

RESULTS AND CONCLUSIONS

The gene was found to be--12 kb in length and made up of five exons (418, 78, 155, 170, and 731 base pairs, respectively). The immediate 5' flanking region did not contain the canonical TATAA box. One DNA source (Clontech promoter finder kit) contained a liver specific nuclear factor response element approximately 550 base pairs from the transcription start site, whereas a second source did not. This and other cis acting factors in the 5' flanking region were identified by computer analysis. The physiological significance of such elements requires detailed experimental evaluation.

The effects of ethanol, 3,5,3'-triiodothyronine (T3) and oestradiol (E2) on thyroid hormone nuclear receptor expression in human hepatocyte primary cultures

The possibility that ethanol regulated the expression of thyroid hormone receptor mRNA levels was explored in a model involving human hepatocyte primary culture. Ethanol (20, 50 and 100 mM for 24 h was found to have no effect on the steady-state levels of either triiodothyronine (T3) receptor alpha 1 or alpha 2 mRNAs. In contrast both T3 (1, 10 and 100 nM) and oestradiol (0.1, 1 and 10 ng/ml) treatments affected either one or both of these mRNA levels in a complex manner, showing that the model was capable of responding to other stimuli. Triiodothyronine receptor beta 1 mRNA was not assayed. The hypermetabolic effects of long-term ethanol consumption in humans appears not to be due to the direct effect of ethanol on the regulation of these receptors.

The structure of the human thyroxine binding globulin (TBG) gene

A portion of the human X-chromosome (> 5 kb) encoding the translated portion of the thyroxine-binding globulin (TBG) gene was sequenced. The primary templates for sequencing were isolated from a human X-chromosome library (two positive plaques from 400,000 screened initially with a TBG cDNA probe) or were produced by PCR amplification using leucocyte genomic DNA as the amplification template. Potential hormone response elements (HREs) were identified at either end of the gene. These HREs have sequences based on the consensus half-site of thyroid hormone response elements, although it is unclear whether the structures are functional HREs. Other potential regulatory elements also were identified towards the 3' end of the gene.