| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥300,000)
Fiscal Year 2007: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2006: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2005: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
Genetic polymorphisms in the drug metabolizing enzymes has been shown to be one of the important factor for interindividual variations of drug responses. However, few cases have reported that the polymorphisms in the 3'-untranslaid region (3'-UTR) altered its protein function, resulting in influence on the response. This study was performed to investigate whether the linked 3 polymorphisms (#IB haplotype) found in the 3'-UTR of UDP-glucuronosyltransferase 1A1 (UGT1A1) gene, as a model, could influence the expression levels of the mRNA and proteins in vitro as well as an in vivo parameter for the UGT1A1 activity. Regarding the in vitro study, expression plasmids for the wild-type and mutant (with #IB haplotype) UGT1A1 were constructed and transfected into COS-1 and HepG2 cells. Total RNA and microsmal fractions were collected in various time after addition of actinomycin D. The mRNA and protein expression levels were analyzed by TaqMan real time PCR and immunoblotting, respectively. In mutant, both expression levels had tendencies to be reduced compared those in the wild-type, but the stabilities were similar in both. As for the in vivo study of 554 Japanese healthy volunteers, total bilirubin concentrations were used as a marker for in vivo UGT1A1 activity since UGT1A1 was involved in the glucuronidation of bilirubin. We showed that either #60or #IB alone had a slight effect on total bilirubin concentrations. The presence of both #60 and #IB on the same DNA strand (#60#IB combinatorial haplotype), however, significantly increased the concentrations. These results suggested that #IB haplotype alone had little effect on UGT1A1 expression (and activity), but in combination with #60 haplotype, it significantly reduced the UGT1A1 function and thus could influence the responses to the drugs metabolized by UGT1A1 in Japanese.
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