The research of the regulation of transcription in histidine decarboxylase gene

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We have been investigating the transcriptional regulation of a gene coding histidine decarboxylase, the enzyme catalyze histamine synthesis reaction. The expression of this gene is restricted to the mast cells, basophils, neuron, gastric wall etc. The cell specific expression is controlled the methylation of the cytosine of promoter-enhancer region of this gene. We studied this phenomenon in chiefly a cell line called P815 which is a mast cell line. The following statement is the summary of the results.1) We cloned the mouse genomic DNA of HDC gene and determined the structure.2) We found that when we treated this cell line with an demethylation agent called 5-azaC, the cell newly expressed HDC gene.3) We transfected this cell line with two kinds of HDC promoter-reporter plasmids ; a plasmid without any methylation and with methylation in the HDC promoter region. The reporter activity was much weaker in the cells with methylated plasmid.4) The P815 cell line with methylated promoter-reporter construct increased the reporter activity after the stimulation with 5-aza C.The mouse HDC gene is controlled by the methylation of the promoter region which is very similar phenomenon seen in human counterparts.We constructed HDC promoter-GFP vector to check the expression of HDC gene by introducing this gene to generate the transgenic mice. These mice can be used for the transcription assay of HDC by various stimuli and the elucidation of the relation between the inducer and the transcriptional activation in vivo.