Fig. 3.

Effect of the histamine N-methyltransferase (HNMT) 939A>G polymorphism on mRNA stability and enzyme activity. The mRNA levels of the pEGFP-HNMT 3'-UTR reporter construct in U937 cells were assessed by real-time PCR after actinomycin D (10 µg/mL) treatment. (A) EGFP mRNA stability according to the 939A>G polymorphism. The P value was determined using repeated measures ANOVA. (B) HNMT enzyme activity was examined by measuring the formation of Nτ-methylhistamine in pHNMT CDS-3'-UTR-transfected U937 cells. The relative enzyme activity (CPM: counts per minute) is represented as the ratio of the activity to the enzyme activity in cells transfected with the empty control vector pcDNA3. The P value was determined by a Mann-Whitney test. Three independent determinations were performed on each sample.