N-glucuronidation catalyzed by UGT1A4 and UGT2B10 in human liver microsomes: Assay optimization and substrate identification

Lu, Danyi; Xie, Qian; Wu, Baojian

doi:10.1016/j.jpba.2017.07.037

Cited by 23 publications

(14 citation statements)

References 25 publications

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“…In particular, the intergenic minor alleles of the lead SNPs rs1670747 (4:69601886-70138176) and rs2926038 (4:69544277-70340670) are responsible for decreasing N-desmethylclozapine levels and increasing the CLZ-to-N-desmethylclozapine ratio by~21% and 25%, respectively. UGT2B10 is involved in N-glucuronidation of a variety of psychotropic drugs including CLZ, and likely Ndesmethylclozapine 39 . These variants might be of potential relevance to genotype before starting CLZ treatment, since increasing N-desmethylclozapine level has been associated with positive effects of CLZ treatment 6,40 , but further studies are required to elucidate if UGT2B10 genotype has an impact on the clinical response of CLZ.…”

Section: Discussionmentioning

confidence: 99%

Identification of a novel polymorphism associated with reduced clozapine concentration in schizophrenia patients—a genome-wide association study adjusting for smoking habits

et al. 2020

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Clozapine (CLZ) is the superior antipsychotic drug for treatment of schizophrenia, but exhibits an extensive interpatient pharmacokinetic variability. Here, we conducted a genome-wide association study (GWAS) of CLZ serum concentration adjusting for known smoking habits, which is a major nongenetic factor reducing CLZ levels. The study included 484 patients with 10,283 steady-state serum concentrations of CLZ and N-desmethylclozapine, prescribed dosing, co-medications and known smoking habits (n = 422; 9284 serum samples) from a therapeutic drug monitoring (TDM) service. The GWAS analyses were performed with and without smoking habits as covariate, where possible hits were assessed in relation to the target CLZ concentration range applied in the TDM service (300–2500 nmol/L). The smoking-independent analysis of N-desmethylclozapine serum concentration and the CLZ-to-N-desmethylclozapine ratio replicated the previously identified locus on chromosome 4. After adjusting for smoking habits in patients confirmed as ‘smokers’ (61%) or ‘nonsmokers’ (39%), a novel variant (rs28379954; minor T>C allele frequency 4.1%; 7.6% CT carriers in the population) within the gene encoding the nuclear factor 1 B-type (NFIB) was significantly associated with reduced CLZ serum concentration (p = 1.68 × 10−8, beta = −0.376; explained variance 7.63%). There was no significant association between rs28379954 and N-desmethylclozapine concentration in the GWAS analysis (p = 5.63 × 10−5). The fraction of CLZ TDM samples below 300 nmol/L was significantly higher in carriers vs. noncarriers of the rs28379954 minor C allele [12.0% (95% CI: 9.4–14.7) vs. 6.2% (95% CI: 5.7–6.8), p < 0.001]. We identified a novel variant in the NFIB gene associated with reduced CLZ levels and increased risk of subtherapeutic serum concentrations. This warrants testing of clinical relevance of screening for this gene variant, and also experimental studies to investigate the biological mechanisms of NFIB involvement in CLZ pharmacokinetics.

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Section: Discussionmentioning

confidence: 99%

Identification of a novel polymorphism associated with reduced clozapine concentration in schizophrenia patients—a genome-wide association study adjusting for smoking habits

et al. 2020

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“…A 5 mM UDPGA concentration is generally used in UGT phenotyping assays in HLMs, although the impact of varying UDPGA concentration has not yet been systematically examined. A recent publication from Lu et al (2017) demonstrated that the maximal metabolic activity of UGT1A4 and UGT2B10 was reached when 8 mM UDPGA was used, which was the highest UDPGA concentration tested.…”

Section: Discussionmentioning

confidence: 91%

Optimization of Experimental Conditions of Automated Glucuronidation Assays in Human Liver Microsomes Using a Cocktail Approach and Ultra-High Performance Liquid Chromatography–Tandem Mass Spectrometry

et al. 2018

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“…S1A). The constant Ca distance of [11][12] A is caused by hydrogen bonding of Arg259 to Asp400 and Asn401, which is not present for Gly259 in UGT1A5*1. Hence, helix Q is allowed to move more freely in UGT1A5*1 than in UGT1A5*8 with the additional hydrogen bonding of Arg259.…”

Section: Homology Modeling For Ugt1a5mentioning

confidence: 97%

“…N ‐glucuronidation is an important pathway for metabolism and disposition of many amines, and within the context of metabolites in safety testing (MIST), N ‐glucuronides are also of interest because they tend to be formed much more in humans than in many other animal species and as such often end up as disproportionate metabolites . UGT1A4 and UGT2B10 are currently being thought to be the most important enzymes catalyzing this reaction type in humans, while UGT1A3 is contributing only to a smaller extent . By contrast, the involvement of UGT1A5, which displays a very high sequence homology to both UGT1A3 and UGT1A4, in N ‐glucuronidation is unknown.…”

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confidence: 99%

A common polymorphic variant of UGT1A5 displays increased activity due to optimized cofactor binding

et al. 2018

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Uridine diphosphate-glucuronosyltransferases (UGTs) are the most important phase II enzymes in human drug metabolism. Using permeabilized recombinant fission yeast cells (enzyme bags), we demonstrate that UGT1A5 can catalyze an N-glucuronidation reaction. We characterized two new polymorphic UGT1A5 variants: a common ninefold mutant (UGT1A5*8) with double-fold activity and a much rarer sixfold mutant (UGT1A5*9), which has the same activity as the wild-type. Molecular modeling studies indicate that the minor effects of all mutations, except for Gly259Arg, are due to their distance to the substrate binding site. Extensive molecular dynamics simulations revealed that the Gly259Arg mutation stabilizes helix Q through a newly formed hydrogen bonding network, which places the cofactor in a much more favorable geometry in UGT1A5*8 as compared to the wild-type.

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N-glucuronidation catalyzed by UGT1A4 and UGT2B10 in human liver microsomes: Assay optimization and substrate identification

Cited by 23 publications

References 25 publications

Identification of a novel polymorphism associated with reduced clozapine concentration in schizophrenia patients—a genome-wide association study adjusting for smoking habits

Identification of a novel polymorphism associated with reduced clozapine concentration in schizophrenia patients—a genome-wide association study adjusting for smoking habits

Optimization of Experimental Conditions of Automated Glucuronidation Assays in Human Liver Microsomes Using a Cocktail Approach and Ultra-High Performance Liquid Chromatography–Tandem Mass Spectrometry

A common polymorphic variant of UGT1A5 displays increased activity due to optimized cofactor binding

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