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Effect of Genotype, Age and Gender on Hepatic Abundance of Flavin Monooxigenase 3
Author(s) -
Xu Meijuan,
Bhatt Deepak Kumar,
Chaw Katrina,
Yeung Catherine,
Prasad Bhagwat
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.669.13
Subject(s) - cyp2a6 , microsome , flavin containing monooxygenase , single nucleotide polymorphism , genotype , chemistry , cyp2e1 , microbiology and biotechnology , cyp1a2 , cytochrome p450 , biology , biochemistry , metabolism , monooxygenase , gene , enzyme
Background and Purpose Hepatic flavin monooxigenase 3 (FMO3) metabolizes a broad array of nucleophilic heteroatom‐containing drugs (e.g., amphetamine, sulindac, benzydamine, ranitidine, tamoxifen and ethioniamide), endogenous and exogenous chemicals (e.g., catecholamine, trimethylamine and nicotine) and pesticides. To predict the effect of genotype, age and gender on the hepatic metabolism of FMO3 substrates, we quantified FMO3 protein abundance in human liver microsomes by LC‐MS/MS proteomics. Methods Human liver microsomes were isolated from the tissue samples procured from University of Washington (UW, n=39) and St. Jude Children's Hospital (SJLB, n=249). Two peptides, i.e., VAIIGAGVSGLASIR (quantifier) and NNLPTAISDWLYVK (qualifier) were selected for LC‐MS/MS quantification. Total protein concentration was determined and the samples were denatured, reduced, alkylated, desalted and digested as previously reported (1, 2). FMO3 was quantified by AB Sciex 6500 triple quadrupole MS/MS using optimum conditions of reproducibility (1). Genotyping and mRNA expression analyses were performed using previously reported methods (3). The functional activity of FMO3 in selected human liver microsomes (UW samples) was quantified by using benzydamine as a probe substrate. Results Genotype and age significantly affect FMO3 protein abundance and activity. Out of the common twenty‐one FMO3 SNPs, six SNPs (rs2064074, rs28363536, rs2266782, rs909530, rs2266780 and rs909531) were associated with significantly decreased protein abundance. However, there was no correlation of these SNPs on the mRNA expression of FMO3 perhaps due to the effect of these SNPs on post‐translational modification, e.g., proteosomal degradation. Based on the activity data on representative samples, human livers harboring variant allele of rs2266780 showed no in vitro metabolic activity toward benzydamine, indicating effect of this SNP on both substrate affinity (Km) and FMO3 protein abundance. Consistent with our previous data (4), infants and children have significantly lower FMO3 abundance as compared to adults. FMO3 abundance was not associated with gender. Conclusions FMO3 protein abundance is highly affected by genotype and age but is independent of gender. These quantitative data are important in predicting FMO3 mediated hepatic N‐oxidation or S‐oxidation of endogenous biomolecules and xenobiotics. Support or Funding Information NICHD R01HD081299‐02