Environmental and Molecular Mutagenesis最新文献

Individual differences in drug response have always existed in clinical treatment. Many non-genetic factors show non-negligible impacts on personalized medicine. Emerging studies have demonstrated epigenetic could connect non-genetic factors and individual treatment differences. We used systematic retrieval methods and reviewed studies that showed individual factors’ impact on DNA methylation of drug metabolism genes. In total, 68 studies were included, and half (n = 36) were cohort studies. Six aspects of individual factors were summarized from the perspective of personalized medicine: parental exposure, environmental pollutants exposure, obesity and diet, drugs, gender and others. The most research (n = 11) focused on ABCG1 methylation. The majority of studies showed non-genetic factors could result in a significant DNA methylation alteration in drug metabolism genes, which subsequently affects the pharmacokinetic processes. However, the underlying mechanism remained unknown. Finally, some viewpoints were presented for future research.

DNA base editors (BEs) composed of a nuclease-deficient Cas9 fused to a DNA-modifying enzyme can achieve on-target mutagenesis without creating double-strand DNA breaks (DSBs). As a result, BEs generate far less DNA damage than traditional nuclease-proficient Cas9 systems, which do rely on the creation of DSBs to achieve on-target mutagenesis. The inability of BEs to create DSBs makes the detection of their undesired off-target effects very difficult. PacBio HiFi sequencing can efficiently detect ultrarare mutations resulting from chemical mutagenesis in whole genomes with a sensitivity ~1 × 10⁻⁸ mutations per base pair. In this proof-of-principle study, we evaluated whether this technique could also detect the on- and off-target mutations generated by a cytosine-to-thymine (C>T) BE targeting the LacZ gene in Escherichia coli (E. coli). HiFi sequencing detected on-target mutant allele fractions ranging from ~7% to ~63%, depending on the single-guide RNA (sgRNA) used, while no on-target mutations were detected in controls lacking the BE. The presence of the BE resulted in a ~3-fold increase in mutation frequencies compared to controls lacking the BE, irrespective of the sgRNA used. These increases were mostly composed of C:G>T:A substitutions distributed throughout the genome. Our results demonstrate that HiFi sequencing can efficiently identify on- and off-target mutations in cell populations that have undergone genome editing.

Cadmium (Cd), a heavy metal, is used in a wide range of applications, such as plastics, electroplating process, electronics, and so forth. Due to its bioaccumulation ability, Cd can contaminate soil, water, air and food. To determine the effect of Cd exposure on the necroptosis in pig spleen and its mechanistic investigation, we constructed a model in pigs by feeding them food containing 20 mg/kg Cd. In this study, we analyzed the effects of Cd exposure on pig spleen through HE staining, Quantitative real-time PCR (qRT-PCR), Western blot (WB), and principal component analysis (PCA). Results show that Cd exposure can destroy the structure and function of pig spleen, which is closely related to necroptosis. Further results show that Cd exposure can induce necroptosis through ROS-mediated activation of Signal transducer and activator of transcription 1/Receptor-Interacting Serine/Threonine-Protein Kinase 3 (STAT1/RIPK3) signaling pathway in pig spleen. Additionally, Cd exposure also can affect the stability of mitochondrial-associated endoplasmic reticulum membrane (MAMs) structure, which also contributes to the process of necroptosis. Our study provides insights into the physiological toxicity caused by Cd exposure.

Deletions associated with the repair of DNA double-strand breaks is a source of genetic alternation and a recognized source of disease-causing mutagenesis. Theta-mediated end joining is a DNA repair mechanism, which guarantees deletions by its employment of microhomology (MH) alignment to facilitate end joining. A lesser-characterized templated insertion ability of this pathway, on the other hand, is associated with both deletion and insertion. This mechanism is characterized by at least one round of polymerase θ-mediated synthesis, which does not result in successful repair, followed by a subsequent round of polymerase engagement and synthesis that does lead to repair. Here we focus on the mechanisms by which polymerase θ introduces these insertions—direct, inverse, and a new class which we have termed strand switching. We observe this new class of templated insertions at multiple loci and across multiple species, often at a comparable frequency to those previously characterized. Templated insertion mutations are often enriched in cancer genomes and repeat expansion disorders. This repair mechanism thus contributes to disease-associated mutagenesis, and may plausibly even promote disease. Characterization of the types of polymerase θ-dependent insertions can provide new insight into these diseases and clinical promise for treatment.

The aim of this study was to compare the kinetics of the in vivo action of equimolar doses of methyl gallate (MG) and epigallocatechin gallate (EGCG) on their capacity to induce DNA damage and to protect against DNA damage induced by ⁶⁰Co gamma rays. DNA-damaged cells were determined by single-cell gel electrophoresis (comets) in murine peripheral blood leukocytes. The maximum radioprotective effects of MG and EGCG (approximately 70%) occurred at 15 min after administration when their effect was determined 2 min following irradiation. MG and EGCG have similar radioprotective indexes, which due to their fast response indicate that they are involved in free radical scavenging. Due to the similar radioprotective activities of MG and EGCG, the in vivo radioprotective effects of these agents do not seem to be dependent on the number of hydroxyl groups present in their structures but instead on the presence of the galloyl radical. EGCG induces an early, significant, and persistent increase in the number of DNA-damaged cells and a later and more important increase in the number of damaged cells, suggesting that it has two mechanisms by which it can induce DNA damage. MG at the same molar dose as EGCG caused a significant and persistent increase in DNA damaged cells but to a much lesser extent to that induce by EGCG, suggesting that the galloyl radical is not involved in the mechanism of DNA breaks induction.

Air pollution is an important environmental factor influencing human health. In this study, we compared chromosome damage in city policemen from three cities in the Czech Republic: industrial Ostrava characterized by high levels of benzo[a]pyrene, Prague with heavy traffic emitting nitrogen oxides, and relatively clean Ceske Budejovice located in an area with predominantly agricultural activity. Chromosomal aberrations in lymphocytes were evaluated by fluorescence in situ hybridization with painting probes for chromosomes 1, 2, 3, and 4 in spring and autumn. An increase in the frequency of unstable chromosome aberrations, that is, dicentric chromosomes and acentric fragments, was observed in spring samples from Ostrava (p = .014 and p = .044, respectively) and Prague (p = .002 and p = .006, respectively) in comparison with Ceske Budejovice. The difference was significant only for samples taken after the winter period, when the concentration of pollutants in the air increases due to poor dispersion conditions. An increased frequency of dicentric chromosomes was observed in spring compared to autumn in both Ostrava and Prague (p = .017 and p = .023, respectively), but not in Ceske Budejovice. More breakpoints were observed on chromosome 1 than on the other chromosomes examined (p < .001). The number of breakpoints in the heterochromatin region 1p11-q12 was lower than in other parts of chromosome 1 (p < .001), suggesting a protective function of heterochromatin against damage. Our study showed, that air pollution increased the frequency of unstable chromosome aberrations, especially dicentric chromosomes. However, we did not show an effect on stable chromosome rearrangements.

N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine-quinone (6PPD-quinone), an oxidation product of the tire additive, 6PPD, has been associated with high mortality of salmonids (0.1 μg/L). The objective of this study was to determine the acute toxicity using neonates and mutagenicity (micronuclei in hemolymph of exposed adults) of 6PPD-quinone in the marine amphipod Parhyale hawaiensis. Also, we studied its mutagenicity in the Salmonella/microsome assay using five strains of Salmonella with and without metabolic system (rat liver S9, 5%). 6PPD-quinone did not present acute toxicity to P. hawaiensis from 31.25 to 500 μg/L. Micronuclei frequency increased after 96 h-exposure to 6PPD-quinone (250 and 500 μg/L) when compared to the negative control. 6PPD-quinone also showed a weak mutagenic effect for TA100 only in the presence of S9. We conclude that 6PPD-quinone is mutagenic to P. hawaiensis and weakly mutagenic to bacteria. Our work provides information for future risk assessment of the presence of 6PPD-quinone in the aquatic environment.

CircRNAs are considered as one of the potential therapeutic targets of multiple cancers. According to accumulating evidence, circRNA regulates cancer progression by acting as a miRNA sponge. In the current work, our data discovered that hsa_circ_0087856 and CITED2 expression was increased, while miR-1184 expression was decreased in BC cell lines and tissues. Hsa_circ_0087856 expression negatively correlated with miR-1184, whereas positively correlated with CITED2. Hsa_circ_0087856 silencing suppressed BC tumor growth, and contributed to the inhibition of cisplatin to tumor growth. In cellular experiments, hsa_circ_0087856 increasing promoted BC cells proliferation, migration and invasion, and inhibited the cells apoptosis. Hsa_circ_0087856 increasing partly reversed the inhibition of cisplatin to BC cell proliferation and the promotion to cell apoptosis. Oppositely, hsa_circ_0087856 silencing could increase the sensitivity of BC cells to cisplatin. Hsa_circ_0087856 promoted CITED2 expression through binding with miR-1184 and inhibiting its expression. CITED2 increasing partly reversed the promotion of hsa_circ_0087856 silencing to cisplatin-induced BC cells apoptosis promotion and proliferation suppression. Overall, our results revealed the role of hsa_circ_0087856 that downregulation its expression could enhance the BC cells sensitivity to cisplatin by facilitating CITED expression via sponging miR-1184. Moreover, our research provided a potential therapeutic target for BC.

Circular RNAs (circRNAs), including circ_0000033, were shown to be abnormally expressed in breast cancer (BC) and play an important regulatory function in the development of this cancer. This study aimed to investigate the action and mechanism of circ_0000033 in BC carcinogenesis. Specifically, levels of genes and proteins were analyzed using quantitative real-time PCR (qRT-PCR) and western blotting. Circ_0000033 was highly expressed in BC tissues and cells. Properties of cells with modified expression of circ_0000033 were characterized using an in vitro colony formation assay, EdU assay, flow cytometry, caspase-3 activity analysis, transwell assay, and tube formation assay, respectively. Functionally, knockdown of circ_0000033 suppressed BC cell proliferation, migration, invasion, angiogenesis, and induced apoptosis and cell cycle arrest in vitro. An in vivo experiment was conducted using a murine xenograft model and showed circ_0000033 silencing also impeded the growth of BC in nude mice. The binding between miR-378a-3p and circ_0000033 or NUAK2 (NUAK Family Kinase 2) was validated using a dual-luciferase reporter assay. Circ_0000033 sequestered miR-378a-3p and resulted in NUAK2 release, indicating a circ_0000033/miR-378a-3p/NUAK2 regulatory network operates in BC cells. Circ_0000033 down-regulation in BC cells was accompanied by decreased NUAK2 and increased miR-378a-3p expression. Moreover, the anticancer effects mediated by circ_0000033 knockdown were abolished by miR-378a-3p inhibition or NUAK2 overexpression in BC cells. Overall, circ_0000033 up-regulates NUAK2 through sequestration miR-378a-3p, which promoted breast tumorigenesis, suggesting circ_0000033 is a promising therapeutic target for BC treatment.