Relationship between mRNA levels quantified by reverse transcription-competitive PCR and metabolic activity of CYP3A4 and CYP2E1 in human liver.
Reverse transcription-competitive polymerase chain reaction is a powerful and sensitive tool for quantifying the absolute amount of mRNA. Using this method with beta-actin as the standard, we measured the mRNA level of CYP3A and CYP2E1 isoforms in human livers. We also determined the metabolic activities for both CYP isoforms. The absolute amounts of CYP3A4 and CYP2E1 mRNA in 15 liver tissues ranged from 15 to 5127 and 15163 to 69289 copies/10(4) copies of beta-actin (341- & 3.6-fold), respectively. The testosterone 6beta-hydroxylation for CYP3A4 and chlorzoxazone 6-hydroxylation activity for CYP2E1 ranged from 30 to 505 pmol/mg/min (16-fold) and from 0.59 to 2.73 nmol/mg/ml (3.6-fold), respectively. The correlation between the mRNA level and activity of CYP3A4 was significant (r = 0.94), while there was no significant correlation for CYP2E1 (r = 0.04). In conclusion, we observed a significant correlation between enzyme activity and mRNA expression for CYP3A4 but not for CYP2E1. This fact indicates that CYP2E1, in addition to being less variable between individuals than CYP3A4, differs in its regulation mechanism.
Sumida
A
A
Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka, 565-0871, Japan.
Kinoshita
K
K
Fukuda
T
T
Matsuda
H
H
Yamamoto
I
I
Inaba
T
T
Azuma
J
J
D000293:Adolescent; D000328:Adult; D019392:Cytochrome P-450 CYP2E1 / Q000032:analysis* / Q000235:genetics; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000032:analysis* / Q000235:genetics; D005260:Female; D006801:Humans; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D008875:Middle Aged; D006899:Mixed Function Oxygenases / Q000032:analysis* / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D044465:White People
D012333:RNA, Messenger; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D019392:Cytochrome P-450 CYP2E1; C104464:CYP3A protein, human; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human