Effect of the genetic mutant G71R in uridine diphosphate-glucuronosyltransferase 1A1 on the conjugation of bilirubin

We aimed to investigate the effect of the genetic mutant G71R (c. 211G > A) in uridine diphosphate (UDP)-glucuronosyltransferase 1A1 (UGT1A1) on the glucuronidation of unconjugated bilirubin. The UGT1A1 wild-type and mutant G71R gene sequences were inserted into the lentiviral vector GV358 plasmid and then transfected into COS-7 cells. Real-time polymerase chain reaction and western blot analyses were used to determine mRNA and protein expression levels of UGT1A1, respectively. High-performance liquid chromatography was used to quantitate the levels of conjugated bilirubin. The results showed no significant difference in the mRNA and protein expression levels between the UGT1A1 wild-type and G71R homozygous and heterozygous mutants. The level of conjugated bilirubin reached a maximum in wild-type UGT1A1-transfected COS-7 cells. However, relative to the UGT1A1 wild-type, conjugated bilirubin concentrations were 71 and 22% with G71R heterozygous- and G71R homozygous-transfected COS-7 cells, respectively. In conclusion, we successfully established in vitro cell models of the UGT1A1 wild-type and the G71R homozygous and heterozygous mutants using a lentiviral vector. Furthermore, the catalytic activity for unconjugated bilirubin was lower in the mutant G71R than the UGT1A1 wild-type enzyme, and a weaker effect was observed in the homozygote.

Automated summary

The study aimed to investigate the effect of the G71R genetic mutant in UGT1A1 on the glucuronidation of unconjugated bilirubin. It was found that the catalytic activity for unconjugated bilirubin was lower in the G71R mutant compared to the wild-type enzyme, with a stronger effect observed in the homozygote.