Expression and genotype-dependent catalytic activity of N-acetyltransferase 2 (NAT2) in human peripheral blood mononuclear cells and its modulation by Sirtuin 1

Abstract

N-acetyltransferase 2 (NAT2) catalyzes the biotransformation of numerous arylamine and hydrazine drugs and carcinogens. Genetic polymorphisms of NAT2 modify drug efficacy and toxicity and susceptibility to diseases such as cancer and type 2 diabetes. Expression of NAT2 has been documented in the liver and gastrointestinal tract but not in other tissues. Deacetylation of cytosolic proteins by sirtuins is a post-translational modification important in regulatory networks of diverse cellular processes. The aim of the present study was to investigate NAT2 expression in peripheral blood mononuclear cells (PBMC) and the effects of NAT2 genotype and Sirtuin 1 (SIRT1). Both NAT2 and SIRT1 proteins were expressed on PBMC. Their expression was more prevalent on CD3+ compared to CD19+ and CD56+ cell populations. N-acetylation capacity of PBMC exhibited a NAT2 gene-dose response toward the N-acetylation of isoniazid. Subjects with rapid NAT2 genotype showed an apparent V of 42.1 ± 2.4; intermediate NAT2 genotypes an apparent V of 22.6 ± 2.2; and slow acetylator NAT2 genotypes an apparent V of 19.9 ± 1.7 nM acetyl-isoniazid/24 h/million cells. The N-acetylation capacity of NAT2 in the presence of SIRT1 enhancer was significantly decreased (p < 0.001), conversely, the transient silencing of SIRT1 resulted in an increase of N-acetylation capacity (p < 0.001). These findings are the first report of NAT2 genotype-dependent expression on PBMC and post-translational modification by SIRT1. These findings constitute a substantial advance in our understanding of human N-acetyltransferase expression and a new much less invasive method for measurement of human NAT2 expression and phenotype.

<p>SIRT1 inhibits hepatocellular carcinoma metastasis by promoting M1 macrophage polarization via NF-&kappa;B pathway</p>

“…As a part of sirtuin family (SIRT1–SIRT7) in mammals, SIRT1 is a conserved deacetylase relying on nicotinamide adenine dinucleotide (NAD)+, which contributes to the regulation of transcriptional silencing and cell viability 19–22. The expression of SIRT1 was significantly increased in the HCC cell line.…”

Association of NAT2 genetic polymorphism with the efficacy of Neurotropin® for the enhancement of aggrecan gene expression in nucleus pulposus cells: a pilot study

“…Generally, NAT2 genetic variants have been linked to decreased enzymatic activity and variable stability, leading to an imbalance in the xenobiotic detoxification and increased susceptibility to different forms of cancer [ 22 , 31 ]. Nevertheless, the rapid NAT2 phenotype has been reported to metabolically activate the toxicity of xenobiotic substances, such as N -hydroxylated heterocyclic aromatic amines (HAAs) via O -acetylation, to form the reactive N -acetoxy species.…”

Human arylamine N-acetyltransferase 2 genotype-dependent protein expression in cryopreserved human hepatocytes

“…NAT1 mRNA and protein expression have been consistently reported to be found across the four different tissues (epithelial, nervous, connective and muscular), as well as, blood cells and major organs 2,4,18 . On the other hand, NAT2 mRNA and protein are primarily expressed in the liver, colon and intestine 3,19 ; however, basal levels of expression can be found in blood cells 20 , and during fetal development 21 . Recent reports have discussed the importance of antibody validation for the specific purpose to be used, not doing so, might lead to misinterpretation of the results due to unspecific binding to its target protein 22,23 .…”