N-acetyltransferase Research Articles

Biochemical and structural basis of polyamine, lysine and ornithine acetylation catalyzed by spermine/spermidine N-acetyl transferase in moss and maize.

Polyamines such as spermidine and spermine are essential regulators of cell growth, differentiation, maintenance of ion balance and abiotic stress tolerance. Their levels are controlled by the spermidine/spermine N1 -acetyltransferase (SSAT) via acetylation to promote either their degradation or export outside the cell as shown in mammals. Plant genomes contain at least one gene coding for SSAT (also named NATA for N-AcetylTransferase Activity). Combining kinetics, HPLC-MS and crystallography, we show that three plant SSATs, one from the lower plant moss Physcomitrium patens and two from the higher plant Zea mays, acetylate various aliphatic polyamines and two amino acids lysine (Lys) and ornithine (Orn). Thus, plant SSATs exhibit a broad substrate specificity, unlike more specific human SSATs (hSSATs) as hSSAT1 targets polyamines, whereas hSSAT2 acetylates Lys and thiaLys. The crystal structures of two PpSSAT ternary complexes, one with Lys and CoA, the other with acetyl-CoA and polyethylene glycol (mimicking spermine), reveal a different binding mode for polyamine versus amino acid substrates accompanied by structural rearrangements of both the coenzyme and the enzyme. Two arginine residues, unique among plant SSATs, hold the carboxyl group of amino acid substrates. The most abundant acetylated compound accumulated in moss was N6 -acetyl-Lys, whereas N5 -acetyl-Orn, known to be toxic for aphids, was found in maize. Both plant species contain very low levels of acetylated polyamines. The present study provides a detailed biochemical and structural basis of plant SSAT enzymes that can acetylate a wide range of substrates and likely play various roles in planta.

NAT8L mRNA oxidation is linked to neurodegeneration in multiple sclerosis

RNA oxidation has been implicated in neurodegeneration, but the underlying mechanism for such effects is unclear. Extensive RNA oxidation occurs within the neurons in multiple sclerosis (MS) brains. Here, we identified selectively oxidized mRNAs in neuronal cells that pertained to neuropathological pathways. N-acetyl aspartate transferase 8 like (NAT8L) is one such transcript, whose translation product enzymatically synthesizes N-acetyl aspartic acid (NAA), a neuronal metabolite important for myelin synthesis. We reasoned that impediment of translation of an oxidized NAT8L mRNA will result in a reduction in its cognate protein, thus lowering the NAA level. This hypothesis is supported by our studies on cells, an animal model, and postmortem human MS brain. Reduced brain NAA level hampers myelin integrity making neuronal axons more susceptible to damage, which contributes to MS neurodegeneration. Overall, this work provides a framework for a mechanistic understanding of the link between RNA oxidation and neurodegeneration.

Detection and tracing of Paucilactobacillus wasatchensis from dairy farm to creamery using N-acetyltransferase (NAT) gene-derived primers

A specific, reliable, and fast PCR method to detect Paucilactobacillus wasatchensis, a heterofermentative lactic acid spoilage bacterium, in dairy products, food contact surfaces, and environmental samples from the farm to the processing plant was developed. A primer set was designed specifically targeting the GNAT family N-acetyltransferase (NAT) gene of Plb. wasatchensis. The PCR method developed was specific for Plb. wasatchensis with a detection limit of 2 log cfu mL−1 with ten-fold concentrated milk sample. The method was further validated through tracing the potential source of Plb. wasatchensis from the dairy farm to the cheese processing plant, and the final product; Plb. wasatchensis was detected in the silage, raw silo, defective Cheddar cheese products, raw milk, as well as food contact surfaces after enrichment. This method provides a quick, simple, reliable way to detect Plb. wasatchensis in source materials, dairy farm, production lines, and final aged hard cheese products.

Nanvuranlat, an L-type amino acid transporter (LAT1) inhibitor for patients with pretreated advanced refractory biliary tract cancer (BTC): Primary endpoint results of a randomized, double-blind, placebo-controlled phase 2 study.

494 Background: LAT1 is a transporter ( SLC7A5) of L-type amino acid. Overexpression in cancer cells supports aggressive proliferation. High expression of LAT1 in tumor specimens has been identified as a predictor of poor prognosis in patients with various cancer types, including BTC. The efficacy and safety of nanvuranlat (JPH203), a first-in-class, single agent that selectively inhibits LAT1, was evaluated in patients with pretreated, advanced, refractory BTC in a placebo-controlled randomized trial. Methods: Patients with four different subtypes of advanced BTC were enrolled: intrahepatic (IHC), extrahepatic (EHC), gallbladder (GBC) and ampulla of Vater (AVC). All were refractory to or intolerant of standard chemotherapy and other investigational medicines. Patients were pre-classified as non-rapid acetylators via N-acetyltransferase 2 ( NAT2), to maximize efficacy/safety by minimizing the metabolism of nanvuranlat. The primary endpoint was progression-free survival (PFS), assessed by blinded independent center review (BICR), using RECIST 1.1. Results: At data cut-off (February 28, 2022), 211 BTC patients were consented at 14 centers in Japan. Using NAT2 testing for classification, a total of 106 patients were randomized (2:1) to nanvuranlat (n = 70) or placebo (n = 36). Nanvuranlat met its primary endpoint and demonstrated a statistically significant improvement in PFS by BICR in comparison with the placebo group (Hazard Ratio = 0.557; 95% CI, 0.3435 – 0.9029; one-sided p = 0.0164). The disease control rate (DCR) in the nanvuranlat group was approximately 25% (average = 24.6%) across all BTC subtypes, while it was 11.4% in the placebo group. Grade 3 adverse events were reported in 30.0% for nanvuranlat vs 22.9% for placebo. Treatment-related adverse event rates were respectively 41.4% and 57.1% in the nanvuranlat and placebo groups. No patient had adverse events leading to nanvuranlat treatment discontinuation, dose reduction, or death. Conclusions: The study met the primary endpoint. LAT1 inhibitor monotherapy with nanvuranlat demonstrated useful clinical efficacy in patients with four different subtypes of pre-treated, advanced, refractory BTC. Safe and highly tolerated profile was also documented. Clinical trial information: UMIN000034080 .

Pharmacokinetic Assessment of Isoniazid and Acetylisoniazid in Carbon Tetrachloride-Induced Liver Injury Model in Wistar Rats.

N-acetyl transferase 2 (NAT2) polymorphism testing could not see the light of success as a biomarker tool in tuberculosis management. Additionally, the antitubercular treatment (ATT) drug's reintroduction regimen variations exist because of the scarcity of robust preclinical evidence on ATT drug metabolism. The experiment was planned to understand the pharmacokinetic (PK) behavior of isoniazid and acetylisoniazid (AcINH) in a Wistar rat model of acute liver injury induced by carbon tetrachloride (CCl4) and preclinical drug-induced liver injury (DILI) model induced with CCl4 + anti-Tuberculosis (TB) drugs together. Thirty rats were used for the experiment and were divided into five groups. All rats were administered a single 0.5 ml/kg CCl4 intraperitoneal injection on day 0 to induce an animal model of DILI. Group I rats received CCl4 alone. Groups II-V were started on additional gavage feedings of isoniazid (H) alone, H plus rifampicin (R), H plus pyrazinamide (Z), and H, R, and Z together, respectively, daily for 21 days subsequently. Isoniazid and AcINH PK assessment was accomplished on day 20 of continuous once-daily dosing. Liver function test (LFT) monitoring was done at baseline on days 1, 7, and 21. On the last day of experiments, all experimental rats were sacrificed. Three-week ATT administration sustained the CCl4-induced LFT changes. Area under the curve (AUC) values for isoniazid and AcINH were found to be 2.24 and 1.69 times higher in the H + R group compared with the CCl4 + H group, respectively (P < 0.05). Isoniazid and AcINH maximum concentration (Cmax) reached the highest, while isoniazid clearance reached the lowest in the H + R group. AcINH AUC increased by double in the CCl4 + Isoniazid+Rifampicin+Pyrazinamide (HRZ) group compared with the CCl4 + H group (P < 0.05). Biochemical, histological, and antioxidant changes were consistent with the new liver injury model's development. Rifampicin almost doubles up the isoniazid and AcINH exposure, in presence if DILI.

The Global Acetylation Profiling Pipeline for Quick Assessment of Protein N-Acetyltransferase Specificity In Cellulo.

Global acetylation profiling (GAP) consists of heterologous expression of a given N-acetyltransferase (NAT) in Escherichia coli to assess its specificity. The remarkable sensitivity and robustness of the GAP pipeline relies on the very low frequency of known N-terminal acetylated proteins in E. coli, including their degree of N-terminal acetylation. Using the SILProNAQ mass spectrometry strategy on bacterial protein extracts, GAP permits easy acquisition of both qualitative and quantitative data to decipher the impact of any putative NAT of interest on the N-termini of newly acetylated proteins. This strategy allows rapid determination of the substrate specificity of any NAT.

Altered Arylamine N-acetyltransferase 1 and miR-1290 Levels in Childhood Acute Lymphoblastic Leukemia: A Pilot Study.

Arylamine N-acetyltransferase 1 and 2 (NAT1 and NAT2) are drug-metabolizing enzymes that play a key role in the development of acute lymphoblastic leukemia (ALL). This study evaluated NAT1 and NAT2 mRNA and protein expression and their enzymatic activity in peripheral blood mononuclear cells (PBMC) from patients with ALL (n=20) and healthy children (n=19) and explored the mechanisms that regulate these enzymes in ALL such as microRNAs (miR-1290, miR-26b) and SNPs. PBMC from patients with ALL showed a decrease in NAT1 mRNA and protein expression. In addition, NAT1 enzymatic activity was decreased in patients with ALL. There was no influence of SNP 559 C>T or 560 G>A on low NAT1 activity. The lower expression of NAT1 might be related to the loss of acetylated histone H3K14 in the NAT1 gene promoter in patients with ALL and the higher relative expression of miR-1290 in the plasma of patients with relapsed ALL compared with healthy controls. There were significantly fewer CD3+/NAT1+ double-positive cells in patients who relapsed compared with control subjects. Based on a t-distributed stochastic neighbor embedding algorithm, CD19+ cells that reappeared in patients with relapse showed low NAT1 expression. In contrast, for NAT2, there were no significant results. The expression and function of NAT1 and miR-1290 levels could be involved in modulating immune cells altered in ALL.

Role of NAT-1 gene polymorphism in the etiology and progression of cervical cancer

Cervical cancer (or carcinoma of cervix) incidences show higher occurrence rate in women population residing in poor socio-economic and unhygienic conditions especially in rural areas. However implication of various effective screening and health programmes in western countries, the incidence of invasive cervical cancer has declined greatly. In spite of that, still today cervical cancer remains the most common cancer in women, next to breast and lung cancer, therefore a leading cause of death in India. Gene polymorphisms modify risk of developing cancer like urinary bladder, colorectal, breast cancer etc. The effect of NAT-1gene polymorphism on cancer risk varies with organ involved, reflecting tissue specific expression of these genes. Strong associations exist with cause and increased risk for development of cervical cancer in individuals carrying specific alleles among the population.

Systematic-review-of-population-pharmacokinetic-models-of-isoniazid-in-children-and-adults-with-tuberculosis

Introduction: Isoniazid (INH) is one of the first-line anti-tuberculosis (anti-TB) drugs that have both bactericidal and bacteriostatic properties depending on the rate of mycobacterial growth. Several population pharmacokinetic (PPK) models of INH were established. This systemic review aims to summarise published PPK parameters of INH in the models and to identify covariates influencing the INH pharmacokinetic parameters of models. Method: A search of publications for PPK analyses of INH in volunteers or TB patients from 2011 to 2021 was conducted in PubMed and Scopus databases. Reviews, methodology articles, non-compartmental analysis, in vitro, and animal studies were excluded. Result: Twelve studies were included in this review. Most of the included studies described the pharmacokinetics of INH as two-compartmental with first-order absorption and elimination in most of the included studies. Eleven studies reported N-acetyltransferase 2 (NAT2) genotype polymorphism as the most common significant covariate affecting the pharmacokinetic parameters of INH. Other common significant covariates reported include body weight (n = 2) and body mass index (BMI) (n = 1). Conclusion: The variability of population clearance parameters of INH was explained mainly by the NAT2 genotype polymorphism. This indicates that to optimise and rationalise the dosing regimen of INH, a patient’s NAT2 genotype should be considered. At the same time, body weight and BMI values should be considered when making dosing adjustments for INH to achieve the therapeutic range.

1449. Therapeutic Drug Monitoring of Isoniazid and Rifampicin and Clinical Outcomes in Adults with Tuberculosis.

Abstract Background Directly Observed Treatment Short Course for Tuberculosis (TB) (DOTS) treatment currently produces a cure rate of 80%. Rifampicin (RMP) and isoniazid (INH) are the main bactericides; both show wide inter-individual pharmacokinetics and narrow therapeutic range. Therapeutic drug monitoring (TDM) of antiTB drugs is a strategy to improve the response to treatment. The aim of this work was to optimize and individualize antiTB treatment based on plasma concentrations of RMP and INH, NAT2 genotyping and the Bayesian estimation of PK parameters. Methods A prospective and analytical study including TB patients under DOTS scheme was performed. Venous blood samples were drawn 2 and 4 hours after last dose; INH and RMP were quantified by liquid chromatography coupled to tandem mass spectrometry. Anthropometric and clinical information was retrieved from medical records. Acetylator phenotype was determined based on NAT2 genotyping by real-time PCR. Bayesian estimation of the PK parameters was performed using NONMEM and dosing scheme was proposed to achieve therapeutic concentrations of RIF and INH. Results A total 62 patients were included from 18 to 80 years and 35 to 117 kg of total body weight. The most frequent was pulmonary infection (40%), 25% of patients had type 2 diabetes mellitus and 58.5% were slow acetylators for the NAT2 gene. Lower INH and RMP plasma concentrations were related to adverse clinical outcome, compared to those patients classified with early clinical success [1.9 vs 3.7 mg/L and 16.9 vs 10.0 mg/L (p&amp;lt; 0.05)]. Results indicate the need to adjust anti-TB drugs dose to more than 50% of the patients who show plasma concentrations outside the range for both drugs. Bayesian dosing performed was validated after individualization by quantification and interpretation of INH and RMP plasma concentrations followed by a narrow medical follow up. Conclusion Even with standard anti-TB treatment, great proportion of patients show subtherapeutic concentrations of RMP and INH which is associated with overall therapeutic failure. TDM is a useful tool to individualize antimicrobials dose and improve clinical outcomes at early stages of active TB. Disclosures All Authors: No reported disclosures.

Association between cigarette smoking and ovarian reserve among women seeking fertility care.

This study examined the association of smoking with ovarian reserve in a cross-sectional study of 207 women enrolled in the Louisville Tobacco Smoke Exposure, Genetic Susceptibility, and Infertility (LOUSSI) Study and assessed effect modification by NAT2 acetylator phenotype. Information on current smoking status was collected using a structured questionnaire and confirmed by cotinine assay. Serum anti-Müllerian hormone (AMH) levels were used to assess ovarian reserve. Diminished ovarian reserve (DOR) was defined as AMH <1ng/mL. Single nucleotide polymorphisms in the NAT2 gene, which metabolizes toxins found in cigarette smoke, were analyzed to determine NAT2 acetylator status. Linear and logistic regression were used to determine the effects of smoking on ovarian reserve and evaluate effect modification by NAT2. Regression analyses were stratified by polycystic ovary syndrome (PCOS) status and adjusted for age. Current smoking status, either passive or active as measured by urinary cotinine assay, was not significantly associated with DOR. For dose-response assessed using self-report, the odds of DOR increased significantly for every additional cigarette currently smoked (Odds ratio, OR:1.08; 95% confidence interval, 95%CI:1.01-1.15); additionally, every 1 pack-year increase in lifetime exposure was associated with an increased odds of DOR among women without PCOS (OR: 1.08 95%CI: 0.99-1.18). These trends appear to be driven by the heavy or long-term smokers. Effect modification by NAT2 genotype was not established. A history of heavy smoking may indicate increased risk of diminished ovarian reserve.

Upregulation of cytidine deaminase in NAT1 knockout breast cancer cells.

Arylamine N-acetyltransferase 1 (NAT1), a phase II metabolic enzyme, is frequently upregulated in breast cancer. Inhibition or depletion of NAT1 leads to growth retardation in breast cancer cells in vitro and in vivo. A previous metabolomics study of MDA-MB-231 breast cancer cells suggests that NAT1 deletion leads to a defect in de novo pyrimidine biosynthesis. In the present study, we observed that NAT1 deletion results in upregulation of cytidine deaminase (CDA), which is involved in the pyrimidine salvage pathway, in multiple breast cancer cell lines (MDA-MB-231, MCF-7 and ZR-75-1). We hypothesized that NAT1 KO MDA-MB-231 cells show differential sensitivity to drugs that either inhibit cellular pyrimidine homeostasis or are metabolized by CDA. The cells were treated with (1) inhibitors of dihydroorotate dehydrogenase or CDA (e.g., teriflunomide and tetrahydrouridine); (2) pyrimidine/nucleoside analogs (e.g., gemcitabine and 5-azacytidine); and (3) naturally occurring, modified cytidines (e.g., 5-formyl-2'-deoxycytidine; 5fdC). Although NAT1 KO cells failed to show differential sensitivity to nucleoside analogs that are metabolized by CDA, they were markedly more sensitive to 5fdC which induces DNA damage in the presence of high CDA activity. Co-treatment with 5fdC and a CDA inhibitor, tetrahydrouridine, abrogated the increase in 5fdC cytotoxicity in NAT1 KO cells, suggesting that the increased sensitivity of NAT1 KO cells to 5fdC is dependent on their increased CDA activity. The present findings suggest a novel therapeutic strategy to treat breast cancer with elevated NAT1 expression. For instance, NAT1 inhibition may be combined with cytotoxic nucleosides (e.g., 5fdC) for breast cancer treatment.

Accumulation and distribution of persistent organic pollutants in surface sediment of the estuarine region and correlation between genetic and environmental factors: A case study

In this study, the accumulation and distribution of nine organochlorine pesticides (OCPs) and seven polychlorinated biphenyls (PCBs) in the An Hoa Estuary, Quang Nam Province, Central Vietnam, and the correlation between genetic and environmental factors have been analyzed and assessed. This study analyzed sediment samples from 15 positions in the An Hoa Estuary during the dry season. The OCP concentrations varied between ND (not detected) and 1.82 μ g/kg (S1), mainly consisting of DDE. The total concentration of PCBs ranged between 1.52–19.5 μ g/kg (highest at S13), with PCB-138 and PCB-153 as the congeners most frequently detected in the analyzed samples. The results show that the ecological risk of OCPs and PCBs in the An Hoa Estuary ranges from low to moderate levels. In order to clarify the significance of genetic factors that can be influenced and affected by environmental factors over a certain period, this study also determined the N-acetyltransferase (NAT) enzyme activity in the population residing in the An Hoa Estuary for a period of 30–50 years to show clearly the relationship between weak environmental and genetic factors in determining the risks for environmental health. Based on the results, out of a total of 72 volunteer participants, the phenotype of the N-acetyltransferase system was determined and divided into two groups: rapid (30.6%) and slow (69.4%). Among them, the slow acetylator phenotype is prevalent in two locations, S11 and S13, with 88% and 91.7% of volunteers, respectively. The rapid acetylator phenotype was detected in 17 of 23 participants at location S7, accounting for more than 77% of the total individuals with the rapid acetylator phenotype in this experiment. • The accumulation of nine OCPs and seven PCBs in sediment was determined and assessed. • The highest OCPs (1.82 μ g/kg) and PCBs (19.5 μ g/kg) were detected at sampling sites S1 and S13, respectively. • The activity of xenobiotics biotransformation enzymatic system N-acetyltransferase was determined. • The relationship between weak environmental factors and genetic factors was examined. • The N-acetyltransferase phenotype of citizens was divided into rapid (30.6%) and slow (69.4%).

Review on Molecular Cross-talk of Biofilm Producing Mechanisms of Staphylococcus aureus

Here the review converses the `molecular cross-talk` of biofuel production mechanisms for Staphylococcus aureus. Staphylococcus aureus is a leading cause of bacterial infections globally in both healthcare and community settings. The succes of this bacterium is the of an expansive repertoire of virulence factors in combination with acquired antibiotic resistance and propensity for biofilm formation. S. aureus leverages these factors to adapt to and subvert the host immune response. With the burgeoning fiels of immunometabolism, is has become clear that the metabolic program of leukocytes dictates their inflammatory status and overall effectiveness is clearing an infection. The treatment of S. aureus infections become complicated due to the capacity of S. aureus �multidrug-resistant� occurs because of biofilm formationon the surfaces depending on biotic and abiotic factors, genetic factors, and numerous environmental, which vary from species to species. A broad range of molecular phenomenon contributes a high range of recalcitrance that is insisting on the biofilm formation. The previous published literature illustrated that all strains of Staphylococcal sp. contain the �ica locus� and several can form biofilms in vitro condition. Absences of �ica locus� results diminish of capability to produce biofuels, along with `PIA gene`, or mediate `N-acetyl glucosaminyl transferase activity� in vitro condition.

Acetyl coenzyme A kinetic studies on N-acetylation of environmental carcinogens by human N-acetyltransferase 1 and its NAT1*14B variant.

N-acetyltransferase 1 (NAT1) is a xenobiotic metabolizing enzyme that uses acetyl coenzyme A (AcCoA) as a cofactor for N-acetylation of many carcinogens including aromatic amines and alkylanilines. NAT1 is characterized by single nucleotide polymorphisms (SNPs) that may modulate affinity towards AcCoA. In the current study, we used Chinese hamster ovary (CHO) cells stably transfected with human NAT1*4 (reference allele) or NAT1*14B (variant allele) to measure AcCoA kinetic parameters for N-acetyltransferase activity measurements towards p-aminobenzoic acid (PABA), 4-aminobiphenyl (4-ABP), β-naphthylamine (BNA), benzidine and 3,4-dimethylaniline (3,4-DMA). Our results showed higher N-acetylation rates for each substrate catalyzed by NAT1*4 compared to NAT1*14B. NAT1*4 exhibited higher affinity to AcCoA when catalyzing the N-acetylation of BNA and benzidine compared to NAT1*14B. The results of the current study provide further insights into differences in carcinogen metabolism among individuals possessing the NAT1*14B haplotype.

Fusarium verticillioides NAT1 (FDB2) N-malonyltransferase is structurally, functionally and phylogenetically distinct from its N-acetyltransferase (NAT) homologues.

Fusarium endophytes damage cereal crops and contaminate produce with mycotoxins. Those fungi overcome the main chemical defence of host via detoxification by a malonyl-CoA-dependent enzyme homologous to xenobiotic metabolizing arylamine N-acetyltransferase (NAT). In Fusarium verticillioides (teleomorph Gibberella moniliformis, GIBMO), this N-malonyltransferase activity is attributed to (GIBMO)NAT1, and the fungus has two additional isoenzymes, (GIBMO)NAT3 (N-acetyltransferase) and (GIBMO)NAT2 (unknown function). We present the crystallographic structure of (GIBMO)NAT1, also modelling other fungal NAT homologues. Monomeric (GIBMO)NAT1 is distinctive, with access to the catalytic core through two "tunnel-like" entries separated by a "bridge-like" helix. In the quaternary arrangement, (GIBMO)NAT1 monomers interact in pairs along an extensive interface whereby one entry of each monomer is covered by the N-terminus of the other monomer. Although monomeric (GIBMO)NAT1 apparently accommodates acetyl-CoA better than malonyl-CoA, dimerization changes the active site to allow malonyl-CoA to reach the catalytic triad (Cys110, His158 and Asp173) via the single uncovered entry, and anchor its terminal carboxyl-group via hydrogen bonds to Arg109, Asn157 and Thr261. Lacking a terminal carboxyl-group, acetyl-CoA cannot form such stabilizing interactions, while longer acyl-CoAs enter the active site but cannot reach catalytic Cys. Other NAT isoenzymes lack such structural features, with (GIBMO)NAT3 resembling bacterial NATs and (GIBMO)NAT2 adopting a structure intermediate between (GIBMO)NAT1 and (GIBMO)NAT3. Biochemical assays confirmed differential donor substrate preference of (GIBMO)NAT isoenzymes, with phylogenetic analysis demonstrating evolutionary separation. Given the role of (GIBMO)NAT1 in enhancing Fusarium pathogenicity, unravelling the structure and function of this enzyme may benefit research into more targeted strategies for pathogen control.

Genetic susceptibility of bladder cancer in the Lebanese population

BackgroundBladder cancer (BC) is the 10th most frequent tumor worldwide. Evidence shows an association between elevated risk of BC and various single nucleotide polymorphisms (SNP). BC incidence was the highest in Lebanon according to Globocan 2018 report, but little is known about the genetic susceptibility of Lebanese people to this disease. We aim to evaluate whether this prominent incidence of BC in Lebanon is attributable to known coding genetic variants.MethodsA case-control study was conducted at Hotel-Dieu de France Hospital, Beirut. A cohort of 51 Lebanese patients with BC were recruited between 2017 and 2020. Whole Exome Sequencing (WES) was performed on peripheral blood samples to detect coding genetic variants in the patients. An in-house database including WES data from 472 Lebanese individuals served as control. Literature review of the genetic predisposition to BC was conducted to establish a database of variants known to influence the risk of BC. In-common SNPs were identified between cases and the aforecited database, and their allelic frequencies was quantified in the former and in controls. Comparative analysis of the allelic frequencies of each in-common SNP was carried out between cases, controls, and the genome aggregation database (gnomAD). Analysis was performed by applying the binomial law and setting the p-value to 10− 10.Results484 polymorphisms associated with BC were extracted from the literature review ;151 of which were in-common with the 206 939 variations detected by WES in our cases. Statistically significant differences (p-value < 10− 10) in allelic frequencies was seen in 11 of the 151 in-common SNPs, but none of which corresponds with a higher BC risk. Moreover, rs4986782 variant in the NAT1 gene is not associated with BC in the Lebanese population. `.ConclusionThis is the first next-generation sequencing (NGS)- based study investigating BC risk in a Lebanese cohort of 51 patients. The majority of known exonic variants in the literature were not associated with BC in our patients. Further studies with larger sample sizes are warranted to explore the association of BC in our population with known non-coding genetic variants, and the remainder of WES-generated private Lebanese variants.

Transcriptional Regulation of Human Arylamine N-Acetyltransferase 2 Gene by Glucose and Insulin in Liver Cancer Cell Lines.

Arylamine N-acetyltransferase 2 (NAT2) is well-known for its role in phase II metabolism of xenobiotics and drugs. More recently, genome wide association studies and murine models implicated NAT2 in regulation of insulin sensitivity and plasma lipid levels. However, the mechanism remains unknown. Transcript levels of human NAT2 varied dynamically in HepG2 (hepatocellular) cells, depending on the nutrient status of the culture media. Culturing the cells in the presence of glucose induced NAT2 mRNA expression as well as its N-acetyltransferase activity significantly. In addition, insulin or acetate treatment also significantly induced NAT2 mRNA. We examined and compared the glucose- and acetate-dependent changes in NAT2 expression to those of genes involved in glucose and lipid metabolism, including FABP1, CPT1A, ACACA, SCD, CD36, FASN, ACLY, G6PC, and PCK1. Genes that are involved in fatty acid transport and lipogenesis, such as FABP1 and CD36, shared a similar pattern of expression with NAT2. In silico analysis of genes co-expressed with NAT2 revealed an enrichment of biological processes involved in lipid and cholesterol biosynthesis and transport. Among these, A1CF (APOBEC1 complementation factor) showed the highest correlation with NAT2 in terms of its expression in normal human tissues. The current study shows, for the first time, that human NAT2 is transcriptionally regulated by glucose and insulin in liver cancer cell lines and that the gene expression pattern of NAT2 is similar to that of genes involved in lipid metabolism and transport.

N-acetyltransferase 2 genetic polymorphism modifies genotoxic and oxidative damage from new psychoactive substances.

The use of new psychoactive substances (NPS) as drugs of abuse is common and increasingly popular, particularly among youth and neglected communities. Recent studies have reported acute toxic effects from these chemicals; however, their long-term toxicity is unknown. Genetic differences between individuals likely affect the toxicity risk. Arylamine N-acetyltransferase 2 (NAT2) capacity differs among individuals due to genetic inheritance. The goal of the present study is to investigate the gene-environment interaction between NAT2 polymorphism and toxicity after exposure to these chemicals. We measured N-acetylation by human NAT1 and NAT2 and found that N-acetylation of NPS is carried out exclusively by NAT2. Differences in N-acetylation between NAT2*4 (reference allele) and NAT2*5B (common variant allele) were highly significant (p < 0.0001). Using DNA repair-deficient genetically engineered Chinese hamster ovary (CHO cells), expressing human CYP1A2 and either NAT2*4 or NAT2*5B, we measured the induction of DNA double-strand breaks ([Formula: see text]H2Ax) following treatment of the CHO cells with increasing concentrations of NPS. The induction of [Formula: see text]H2Ax showed a NAT2 allele-dependent response, higher in the NAT2*4 vs NAT2*5B alleles (p < 0.05). Induction of oxidative stress (ROS/RNS) was evaluated; we observed NAT2 allele-dependent response for all compounds in concentrations as low as 10 [Formula: see text]M, where NAT2*4 showed increased ROS/RNS vs NAT2*5B (p < 0.05). In summary, NPS are N-acetylated by NAT2 at rates higher in cells expressing NAT2*4 than NAT2*5B. Exposure to psychoactive chemicals results in genotoxic and oxidative damage that is modified by the NAT2 genetic polymorphism.

Fluorescence-based visual analysis and inhibitor screening of Arylamine N-acetyltransferase 2, a key enzyme for tuberculosis

Tuberculosis is a global epidemic caused by pathogenic Mycobacterium tuberculosis (Mtb), which seriously threatens human life. Arylamine N-acetyltransferase 2 (NAT2) is a vital enzyme in the synthesis of Mtb wall, and closely related to the growth of Mtb. Herein, a fluorescence-based recognition tool (BDPN) has been developed for rapid, sensitive, and selective detection of NAT2 activity in Mtb. As well as a visual high-throughput screening approach for NAT2 inhibitors was established based on BDPN, and four active natural compounds derived from Psoraleae Fructus were discovered that exhibited strong inhibitory effect toward NAT2. Furthermore, Isobavachalcone exhibited the considerable anti-tuberculosis effect through prominently destroying the bacterial cell wall of Mtb and slow down its growth. Moreover, Isobavachalcone could delay the elimination of the anti-tuberculosis drug Isoniazid (INH) mediated by NAT2 and enhance anti-tuberculosis effect of INH. In summary, BDPN was a promising tool for monitoring endogenous NAT2 in Mtb and provided some useful guidance for the rational administration of anti-tuberculosis drug.