Cytochrome P450 phenotyping using the Geneva cocktail improves metabolic capacity prediction in a hospitalized patient population.

Aims: Liver cytochromes (CYPs) play an important role in drug metabolism but display a large interindividual variability resulting both from genetic and environmental factors. Most drug dose adjustment guidelines are based on genetics performed in healthy volunteers. However, hospitalized patients are not only more likely to be the target of new prescriptions and drug treatment modifications than healthy volunteers, but will also be more subject to polypharmacy, drug-drug interactions, or to suffer from disease or inflammation affecting CYP activities.

Insights into the genomic and functional divergence of NAT gene family to serve microbial secondary metabolism.

Microbial NAT enzymes, which employ acyl-CoA to acylate aromatic amines and hydrazines, have been well-studied for their role in xenobiotic metabolism. Some homologues have also been linked to secondary metabolism, but this function of NAT enzymes is not as well-known. For this comparative study, we surveyed sequenced microbial genomes to update the list of formally annotated NAT genes, adding over 4000 new sequences (mainly bacterial, but also archaeal, fungal and protist) and portraying a broad but not universal distribution of NATs in the microbiocosmos.

Differential expression of NAT1 pharmacogene in hormone receptor positive vs. negative female breast tumors may affect drug treatment.

Studies have reported overexpression of NAT1 gene for xenobiotic metabolizing arylamine N -acetyltransferase type 1 in estrogen receptor positive breast tumors, and this association has been linked to patient chemoresistance and response to tamoxifen. We probed the expression of NAT1 , using quantitative reverse transcription PCR to screen clinically characterized breast cancer tissue cDNA arrays. Primers detecting all NAT1 alternative transcripts were used, and the protocol and results are reported according to consensus guidelines.

Human N-acetyltransferase 2 () gene variability in Brazilian populations from different geographical areas.

Several polymorphisms altering the activity have already been identified. The geographical distribution of variants has been extensively studied and has been demonstrated to vary significantly among different ethnic population. Here, we describe the genetic variability of human N-acetyltransferase 2 () gene and the predominant genotype-deduced acetylation profiles of Brazilians.

Joint Analysis of Phenotypic and Genomic Diversity Sheds Light on the Evolution of Xenobiotic Metabolism in Humans.

Variation in genes involved in the absorption, distribution, metabolism, and excretion of drugs (ADME) can influence individual response to a therapeutic treatment. The study of ADME genetic diversity in human populations has led to evolutionary hypotheses of adaptation to distinct chemical environments. Population differentiation in measured drug metabolism phenotypes is, however, scarcely documented, often indirectly estimated via genotype-predicted phenotypes.

A taxonomically representative strain collection to explore xenobiotic and secondary metabolism in bacteria.

Bacteria employ secondary metabolism to combat competitors, and xenobiotic metabolism to survive their chemical environment. This project has aimed to introduce a bacterial collection enabling comprehensive comparative investigations of those functions. The collection comprises 120 strains (Proteobacteria, Actinobacteria and Firmicutes), and was compiled on the basis of the broad taxonomic range of isolates and their postulated biosynthetic and/or xenobiotic detoxification capabilities.

Comparative Investigation of 15 Xenobiotic-Metabolizing -Acetyltransferase (NAT) Homologs from Bacteria.

Arylamines constitute a large group of industrial chemicals detoxified by certain bacteria through conjugation reactions catalyzed by -acetyltransferase (NAT) enzymes. NAT homologs, mostly from pathogenic bacteria, have been the subject of individual studies that do not lend themselves to direct comparisons. By implementing a practicable pipeline, we carried out a comparative investigation of 15 NAT homologs from 10 bacteria, mainly bacilli, streptomycetes, and one alphaproteobacterium.

Functional variability of rhesus macaque (Macaca mulatta) NAT2 gene for drug-metabolising arylamine N-acetyltransferase 2.

Human NAT2 is a polymorphic pharmacogene encoding for N-acetyltransferase 2, a hepatic enzyme active towards arylamine and arylhydrazine drugs, including the anti-tubercular antibiotic isoniazid. The isoenzyme also modulates susceptibility to chemical carcinogenesis, particularly of the bladder. Human NAT2 represents an ideal model for anthropological investigations into the demographic adaptation of worldwide populations to their xenobiotic environment.

The actinobacterium Tsukamurella paurometabola has a functionally divergent arylamine N-acetyltransferase (NAT) homolog.

Actinobacteria in the Tsukamurella genus are aerobic, high-GC, Gram-positive mycolata, considered as opportunistic pathogens and isolated from various environmental sources, including sites contaminated with oil, urban or industrial waste and pesticides. Although studies look into xenobiotic biotransformation by Tsukamurella isolates, the relevant enzymes remain uncharacterized. We investigated the arylamine N-acetyltransferase (NAT) enzyme family, known for its role in the xenobiotic metabolism of prokaryotes and eukaryotes.

Population variability of rhesus macaque (Macaca mulatta) NAT1 gene for arylamine N-acetyltransferase 1: Functional effects and comparison with human.

Human NAT1 gene for N-acetyltransferase 1 modulates xenobiotic metabolism of arylamine drugs and mutagens. Beyond pharmacogenetics, NAT1 is also relevant to breast cancer. The population history of human NAT1 suggests evolution through purifying selection, but it is unclear whether this pattern is evident in other primate lineages where population studies are scarce.

Functional expression of human arylamine N-acetyltransferase NAT1*10 and NAT1*11 alleles: a mini review.

The arylamine N-acetyltransferase (NAT) nomenclature committee assigns functional phenotypes for human arylamine N-acetyltransferase 1 (NAT1) alleles in those instances in which the committee determined a consensus has been achieved in the scientific literature. In the most recent nomenclature update, the committee announced that functional phenotypes for NAT1*10 and NAT1*11 alleles were not provided owing to a lack of consensus. Phenotypic inconsistencies observed among various studies for NAT1*10 and NAT1*11 may be owing to variable allelic expression among different tissues, the limitations of the genotyping assays (which mostly relied on techniques not involving direct DNA sequencing), the differences in recombinant protein expression systems used (bacteria, yeast, and mammalian cell lines) and/or the known inherent instability of human NAT1 protein, which requires very careful handling of native and recombinant cell lysates.

Comparative analysis of xenobiotic metabolising N-acetyltransferases from ten non-human primates as in vitro models of human homologues.

Xenobiotic metabolising N-acetyltransferases (NATs) perform biotransformation of drugs and carcinogens. Human NAT1 is associated with endogenous metabolic pathways of cells and is a candidate drug target for cancer. Human NAT2 is a well-characterised polymorphic xenobiotic metabolising enzyme, modulating susceptibility to drug-induced toxicity.

Homologues of xenobiotic metabolizing N-acetyltransferases in plant-associated fungi: Novel functions for an old enzyme family.

Plant-pathogenic fungi and their hosts engage in chemical warfare, attacking each other with toxic products of secondary metabolism and defending themselves via an arsenal of xenobiotic metabolizing enzymes. One such enzyme is homologous to arylamine N-acetyltransferase (NAT) and has been identified in Fusarium infecting cereal plants as responsible for detoxification of host defence compound 2-benzoxazolinone. Here we investigate functional diversification of NAT enzymes in crop-compromising species of Fusarium and Aspergillus, identifying three groups of homologues: Isoenzymes of the first group are found in all species and catalyse reactions with acetyl-CoA or propionyl-CoA.

Polymorphism p.Val231Ile alters substrate selectivity of drug-metabolizing arylamine N-acetyltransferase 2 (NAT2) isoenzyme of rhesus macaque and human.

Arylamine N-acetyltransferases (NATs) are polymorphic enzymes mediating the biotransformation of arylamine/arylhydrazine xenobiotics, including pharmaceuticals and environmental carcinogens. The NAT1 and NAT2 genes, and their many polymorphic variants, have been thoroughly studied in humans by pharmacogeneticists and cancer epidemiologists. However, little is known about the function of NAT homologues in other primate species, including disease models.

Rapid birth-and-death evolution of the xenobiotic metabolizing NAT gene family in vertebrates with evidence of adaptive selection.

Background: The arylamine N-acetyltransferases (NATs) are a unique family of enzymes widely distributed in nature that play a crucial role in the detoxification of aromatic amine xenobiotics. Considering the temporal changes in the levels and toxicity of environmentally available chemicals, the metabolic function of NATs is likely to be under adaptive evolution to broaden or change substrate specificity over time, making NATs a promising subject for evolutionary analyses. In this study, we trace the molecular evolutionary history of the NAT gene family during the last ~450 million years of vertebrate evolution and define the likely role of gene duplication, gene conversion and positive selection in the evolutionary dynamics of this family.

Arylamine N-acetyltransferases--from drug metabolism and pharmacogenetics to identification of novel targets for pharmacological intervention.

Arylamine N-acetyltransferases (NATs) are defined as xenobiotic metabolizing enzymes, adding an acetyl group from acetyl coenzyme A (CoA) to arylamines and arylhydrazines. NATs are found in organisms from bacteria and fungi to vertebrates. Several isoenzymes, often polymorphic, may be present in one organism.

Comparative genomic and phylogenetic investigation of the xenobiotic metabolizing arylamine N-acetyltransferase enzyme family.

Arylamine N-acetyltransferases (NATs) are xenobiotic metabolizing enzymes characterized in several bacteria and eukaryotic organisms. We report a comprehensive phylogenetic analysis employing an exhaustive dataset of NAT-homologous sequences recovered through inspection of 2445 genomes. We describe the first NAT homologues in viruses, archaea, protists, many fungi and invertebrates, providing complete annotations in line with the consensus nomenclature.

Characterisation of CpG methylation in the upstream control region of mouse Nat2: evidence for a gene-environment interaction in a polymorphic gene implicated in folate metabolism.

Human arylamine N-acetyltransferase 1 (NAT1), a polymorphic xenobiotic metabolising enzyme, has been investigated in relation to susceptibility and prognosis in certain types of cancer. Both human NAT1 and its murine equivalent NAT2 have previously been shown to play roles in the catabolism of folate, which is required for the synthesis of S-adenosylmethionine, the methyl donor for cellular methylation reactions. We have tested whether the expression of mouse Nat2 is subject to epigenetic regulation, specifically CpG methylation in the promoter region, by determining levels of 5-methylcytosine by bisulphite sequencing and methylation-specific PCR.

Arylamine N-acetyltransferases in prokaryotic and eukaryotic genomes: a survey of public databases.

Arylamine N-acetyltransferases (NATs) are xenobiotic metabolizing enzymes found in prokaryotes and eukaryotes. NATs have been characterized in bacteria (Bacilli, Mycobacteria, Salmonella etc.), laboratory animals (chicken, rabbit, rodents etc.

Arylamine N-acetyltransferases: from structure to function.

Arylamine N-acetyltransferases (NATs) are cytosolic conjugating enzymes which transfer an acetyl group from acetylCoenzyme A to a xenobiotic acceptor substrate. The enzyme has an active site cysteine as part of a catalytic triad with histidine and aspartate. NATs have had an important role in pharmacogenetics.

Current trends in N-acetyltransferase research arising from the 2007 International NAT Workshop.

Arylamine N-acetyltransferase (NAT) research has been influenced in recent years by the rapid progress in genomics, proteomics, structural genomics and other cutting-edge disciplines. To keep up with these advancements, the NAT scientific community has fostered collaboration and exchange of know-how between its members. As a specialized event bringing together experts from many different laboratories, the triennial International NAT Workshop has been instrumental in maintaining this culture over the past ten years.

EXEL-7647 inhibits mutant forms of ErbB2 associated with lapatinib resistance and neoplastic transformation.

Purpose: Mutations associated with resistance to kinase inhibition are an important mechanism of intrinsic or acquired loss of clinical efficacy for kinase-targeted therapeutics. We report the prospective discovery of ErbB2 mutations that confer resistance to the small-molecule inhibitor lapatinib.

Experimental Design: We did in vitro screening using a randomly mutagenized ErbB2 expression library in Ba/F3 cells, which were dependent on ErbB2 activity for survival and growth.