RT Journal Article
SR Electronic
T1 Quantitative Analysis of UDP-Glucuronosyltransferase (UGT) 1A and UGT2B Expression Levels in Human Livers
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 1759
OP 1768
DO 10.1124/dmd.109.027227
VO 37
IS 8
A1 Takeshi Izukawa
A1 Miki Nakajima
A1 Ryoichi Fujiwara
A1 Hiroyuki Yamanaka
A1 Tatsuki Fukami
A1 Masataka Takamiya
A1 Yasuhiro Aoki
A1 Shin-ichi Ikushiro
A1 Toshiyuki Sakaki
A1 Tsuyoshi Yokoi
YR 2009
UL http://dmd.aspetjournals.org/content/37/8/1759.abstract
AB UDP-glucuronosyltransferases (UGTs) catalyze glucuronidation of a variety of xenobiotics and endobiotics. UGTs are divided into two families, UGT1 and UGT2. The purpose of this study was to estimate the absolute expression levels of each UGT isoform in human liver and to evaluate the interindividual variability. Real-time reverse transcriptase-polymerase chain reaction analysis was performed to determine the copy numbers of nine functional UGT1A isoforms and seven UGT2B isoforms. We noticed that not only primers but also templates as a standard for quantification should prudently be selected. Once we established appropriate conditions, the mRNA levels of each UGT isoform in 25 individual human livers were determined. UGT1A1 (0.9–138.5), UGT1A3 (0.1–66.6), UGT1A4 (0.1–143.3), UGT1A6 (1.0–70.4), UGT1A9 (0.3–132.4), UGT2B4 (0.3–615.0), UGT2B7 (0.2–97.4), UGT2B10 (0.7–253.2), UGT2B15 (0.3–107.8), and UGT2B17 (0.5–157.1) were substantially expressed (×104 copy/μg RNA) with large interindividual variability. Abundant isoforms were UGT2B4 and UGT2B10, followed by UGT1A1, UGT2B15, and UGT1A6. The sum of the UGT2B mRNA levels was higher than that of UGT1A mRNA levels. It is interesting to note that the mRNA levels normalized with glyceraldehyde-3-phosphate dehydrogenase mRNA for almost UGT isoforms that are substantially expressed in liver showed significant correlations to each other. Western blot analysis was performed using antibodies specific for UGT1A1, UGT1A4, UGT1A6, or UGT2B7. Correlation between the protein and mRNA levels was observed in only UGT1A1 (r = 0.488; p < 0.01). In conclusion, this study comprehensively determined the absolute values of mRNA expression of each UGT isoform in human livers and found considerable interindividual variability.