Involvement of N-6 Adenine-Specific DNA Methyltransferase 1 (
            <i>N6AMT1</i>
            ) in Arsenic Biomethylation and Its Role in Arsenic-Induced Toxicity

Ren, Xuefeng; Aleshin, Maria; Jo, William J.; Dills, Russel; Kalman, David A.; Vulpe, Chris D.; Smith, Martyn T.; Zhang, Luoping

doi:10.1289/ehp.1002733

Cited by 67 publications

(50 citation statements)

References 36 publications

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“…The A. niger genomic sequences were obtained from the Central Aspergillus Data Repository (CADRE) (www.cadre-genomes.org.uk/Aspergillus_niger/). The putative arsenic homeostasis genes in Aspergillus niger were found by comparing gene and protein sequences with those of S. cerevisiae (12,35,39,49,61,62,66) using nucleotide-BLAST and protein-BLAST from the National Center for Biotechnology Information (http://blast.ncbi.nlm.nih .gov/Blast.cgi).…”

Section: Methodsmentioning

confidence: 99%

Role of Aspergillus niger acrA in Arsenic Resistance and Its Use as the Basis for an Arsenic Biosensor

Choe

Gravelat

Abdallah

et al. 2012

Appl Environ Microbiol

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ABSTRACTArsenic contamination of groundwater sources is a major issue worldwide, since exposure to high levels of arsenic has been linked to a variety of health problems. Effective methods of detection are thus greatly needed as preventive measures. In an effort to develop a fungal biosensor for arsenic, we first identified seven putative arsenic metabolism and transport genes inAspergillus niger, a widely used industrial organism that is generally regarded as safe (GRAS). Among the genes tested for RNA expression in response to arsenate,acrA, encoding a putative plasma membrane arsenite efflux pump, displayed an over 200-fold increase in gene expression in response to arsenate. We characterized the function of thisA. nigerprotein in arsenic efflux by gene knockout and confirmed that AcrA was located at the cell membrane using an enhanced green fluorescent protein (eGFP) fusion construct. Based on our observations, we developed a putative biosensor strain containing a construct of the native promoter ofacrAfused withegfp. We analyzed the fluorescence of this biosensor strain in the presence of arsenic using confocal microscopy and spectrofluorimetry. The biosensor strain reliably detected both arsenite and arsenate in the range of 1.8 to 180 μg/liter, which encompasses the threshold concentrations for drinking water set by the World Health Organization (10 and 50 μg/liter).

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Section: Methodsmentioning

confidence: 99%

Role of Aspergillus niger acrA in Arsenic Resistance and Its Use as the Basis for an Arsenic Biosensor

Choe

Gravelat

Abdallah

et al. 2012

Appl Environ Microbiol

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“…We and others have published data on genes involved in resistance to toxic metabolites of arsenic [33], benzene [34], and benzo[a]pyrene [35], formaldehyde [36, 37] as well as mechanisms of toxicity associated with these chemicals. In follow up studies, we validated the roles of human orthologs of some of the yeast genes associated with benzene [38–40] and arsenic [41, 42] toxicity in mammalian cell lines using RNAi-based in vitro knockdown approaches.…”

Section: Functional Genomics In Yeastmentioning

confidence: 99%

“…As mentioned in Section 2.2., we used RNAi to knockdown and validate the functional roles of human orthologs of genes identified in yeast screens associated with benzene [38–40] and arsenic [41, 42] in mammalian cell lines. The flexibility of the approach has allowed RNAi to become one of the most powerful tools for genome-wide characterization of gene functions and it is adaptable to HTS.…”

Section: Functional Genomics By Rna Interference (Rnai)mentioning

confidence: 99%

Functional genomic screening approaches in mechanistic toxicology and potential future applications of CRISPR-Cas9

Shen¹,

McHale²,

Smith³

et al. 2015

Mutation Research/Reviews in Mutation Research

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Characterizing variability in the extent and nature of responses to environmental exposures is a critical aspect of human health risk assessment. Chemical toxicants act by many different mechanisms, however, and the genes involved in adverse outcome pathways (AOPs) and AOP networks are not yet characterized. Functional genomic approaches can reveal both toxicity pathways and susceptibility genes, through knockdown or knockout of all non-essential genes in a cell of interest, and identification of genes associated with a toxicity phenotype following toxicant exposure. Screening approaches in yeast and human near-haploid leukemic KBM7 cells, have identified roles for genes and pathways involved in response to many toxicants but are limited by partial homology among yeast and human genes and limited relevance to normal diploid cells. RNA interference (RNAi) suppresses mRNA expression level but is limited by off-target effects (OTEs) and incomplete knockdown. The recently developed gene editing approach called clustered regularly interspaced short palindrome repeats-associated nuclease (CRISPR)-Cas9, can precisely knock-out most regions of the genome at the DNA level with fewer OTEs than RNAi, in multiple human cell types, thus overcoming the limitations of the other approaches. It has been used to identify genes involved in the response to chemical and microbial toxicants in several human cell types and could readily be extended to the systematic screening of large numbers of environmental chemicals. CRISPR-Cas9 can also repress and activate gene expression, including that of non-coding RNA, with near-saturation, thus offering the potential to more fully characterize AOPs and AOP networks. Finally, CRISPR-Cas9 can generate complex animal models in which to conduct preclinical toxicity testing at the level of individual genotypes or haplotypes. Therefore, CRISPR-Cas9 is a powerful and flexible functional genomic screening approach that can be harnessed to provide unprecedented mechanistic insight in the field of modern toxicology.

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“…These findings suggest that although AS3MT may be the predominant enzyme in the pathway for As 2 O 3 methylation, there could be AS3MT-independent mechanisms and unidentified methyltransferases involved in alternative As 2 O 3 methylation pathways. [46][47][48][49][50] In order to demonstrate that As 2 O 3 as a DNA methylation inhibitor can induce hypomethylation of aberrantly methylated cell cycle regulatory genes in breast cancer cells, we examined the methylation status of promoterassociated CpG islands of the RBL1, RASSF1A, and cyclin D2, before and after treatment with As 2 O 3 by MSP in MCF-7, MDA-MB-231, and MDA-MB-468 cell lines. Treatment with 3 µM of As 2 O 3 for 48 h induced hypomethylation of the partially or fully hypermethylated CpG islands around the promoter regions of the RBL1, RASSF1A, and cyclin D2 genes in all three cell lines.…”

Section: Tp53mentioning

confidence: 99%

Demethylation and alterations in the expression level of the cell cycle–related genes as possible mechanisms in arsenic trioxide–induced cell cycle arrest in human breast cancer cells

et al. 2017

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Arsenic trioxide (As 2 O 3 ) has been used clinically as an anti-tumor agent. Its mechanisms are mostly considered to be the induction of apoptosis and cell cycle arrest. However, the detailed molecular mechanisms of its anti-cancer action through cell cycle arrest are poorly known. Furthermore, As 2 O 3 has been shown to be a potential DNA methylation inhibitor, inducing DNA hypomethylation. We hypothesize that As 2 O 3 may affect the expression of cell cycle regulatory genes by interfering with DNA methylation patterns. To explore this, we examined promoter methylation status of 24 cell cycle genes in breast cancer cell lines and in a normal breast tissue sample by methylation-specific polymerase chain reaction and/or restriction enzyme-based methods. Gene expression level and cell cycle distribution were quantified by real-time polymerase chain reaction and flow cytometric analyses, respectively. Our methylation analysis indicates that only promoters of RBL1 (p107), RASSF1A, and cyclin D2 were aberrantly methylated in studied breast cancer cell lines. As 2 O 3 induced CpG island demethylation in promoter regions of these genes and restores their expression correlated with DNA methyltransferase inhibition. As 2 O 3 also induced alterations in messenger RNA expression of several cell cycle-related genes independent of demethylation. Flow cytometric analysis revealed that the cell cycle arrest induced by As 2 O 3 varied depending on cell lines, MCF-7 at G1 phase and both MDA-MB-231 and MDA-MB-468 cells at G2/M phase. These changes at transcriptional level of the cell cycle genes by the molecular mechanisms dependent and independent of demethylation are likely to represent the mechanisms of cell cycle redistribution in breast cancer cells, in response to As 2 O 3 treatment.

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Involvement of N-6 Adenine-Specific DNA Methyltransferase 1 ( N6AMT1 ) in Arsenic Biomethylation and Its Role in Arsenic-Induced Toxicity

Cited by 67 publications

References 36 publications

Role of Aspergillus niger acrA in Arsenic Resistance and Its Use as the Basis for an Arsenic Biosensor

Role of Aspergillus niger acrA in Arsenic Resistance and Its Use as the Basis for an Arsenic Biosensor

Functional genomic screening approaches in mechanistic toxicology and potential future applications of CRISPR-Cas9

Demethylation and alterations in the expression level of the cell cycle–related genes as possible mechanisms in arsenic trioxide–induced cell cycle arrest in human breast cancer cells

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