RT Journal Article
SR Electronic
T1 Multiplexed Targeted Quantitative Proteomics Predicts Hepatic Glucuronidation Potential
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 1331
OP 1335
DO 10.1124/dmd.115.065391
VO 43
IS 9
A1 Guillaume Margaillan
A1 Michèle Rouleau
A1 Kathrin Klein
A1 John K. Fallon
A1 Patrick Caron
A1 Lyne Villeneuve
A1 Philip C. Smith
A1 Ulrich M. Zanger
A1 Chantal Guillemette
YR 2015
UL http://dmd.aspetjournals.org/content/43/9/1331.abstract
AB Phase II metabolism is prominently governed by UDP-glucuronosyltransferases (UGTs) in humans. These enzymes regulate the bioactivity of many drugs and endogenous small molecules in many organs, including the liver, a major site of regulation by the glucuronidation pathway. This study determined the expression of hepatic UGTs by targeted proteomics in 48 liver samples and by measuring the glucuronidation activity using probe substrates. It demonstrates the sensitivity and accuracy of nano-ultra-performance liquid chromatography with tandem mass spectrometry to establish the complex expression profiles of 14 hepatic UGTs in a single analysis. UGT2B7 is the most abundant UGT in our collection of livers, expressed at 69 pmol/mg microsomal proteins, whereas UGT1A1, UGT1A4, UGT2B4, and UGT2B15 are similarly abundant, averaging 30–34 pmol/mg proteins. The average relative abundance of these five UGTs represents 81% of the measured hepatic UGTs. Our data further highlight the strong relationships in the expression of several UGTs. Most notably, UGT1A4 correlates with most measured UGTs, and the expression levels of UGT2B4/UGT2B7 displayed the strongest correlation. However, significant interindividual variability is observed for all UGTs, both at the level of enzyme concentrations and activity (coefficient of variation: 45%–184%). The reliability of targeted proteomics quantification is supported by the high correlation between UGT concentration and activity. Collectively, these findings expand our understanding of hepatic UGT profiles by establishing absolute hepatic concentrations of 14 UGTs and further suggest coregulated expression between most abundant hepatic UGTs. Data support the value of multiplexed targeted quantitative proteomics to accurately assess specific UGT concentrations in liver samples and hepatic glucuronidation potential.