Environmental and Molecular Mutagenesis最新文献

The mitochondria (mt) and nucleus engage in a dynamic bidirectional communication to maintain cellular homeostasis, regulating energy production, stress response, and cell fate. Anterograde signaling directs mt function, while retrograde signaling conveys metabolic and stress-related changes from mt to the nucleus. Central to this crosstalk is mitochondrial DNA (mtDNA), which encodes key oxidative phosphorylation components. MtDNA integrity is preserved through quality control mechanisms, including fusion and fission dynamics, mitophagy, and nuclear-encoded DNA repair. Disruption in these pathways contributes to mt dysfunction, oxidative stress, and genetic instability—hallmarks of aging and diseases. Additionally, redox signaling and NAD+ homeostasis integrate mt and nuclear responses, modulating transcriptional programs that support mt biogenesis and stress adaptation. This review explores the molecular mechanisms coordinating mito-nuclear interactions, emphasizing their role in maintaining mtDNA integrity and cellular equilibrium. Understanding these processes provides insights into how mt dysfunction drives aging and disease, paving the way for targeted therapeutic strategies.

Tattoo inks contain several substances, including organic and inorganic pigments, additives, and solvents, which may pose a health risk to not only the tattooed skin but also to other parts of the human body due to intradermal exposure. Substances in tattoo inks are regulated by entry 75 in Annex XVII of REACH Regulation (EC) No. 1907/2006. However, despite these legal requirements, a well-defined criterion for the safety assessment of tattoo inks remains lacking. In this context, 2021 BfR opinion titled “Tattoo inks: minimum requirements and test methods” proposed a comprehensive risk assessment of pigments using in vitro/in-chemico data in accordance with OECD Guidelines and CLP Regulations. In the absence of experimental data, new approach methodologies (NAMs) may be used for data-gap filling. Therefore, this work evaluates the applicability of in silico NAMs for data-gap filling for a list of tattoo ink ingredients identified by the Joint Research Centre (JRC) and BfR for genotoxicity assessment. Experimental in vitro genotoxicity data were acquired from the International Uniform Chemical Information Database (IUCLID) which makes non-confidential REACH Study Results publicly accessible. The specific aims of this analysis were the evaluation of in silico genotoxicity predictions from publicly available QSAR tools and structural alerts, the development and validation of new QSAR models specific to tattoo ink ingredients, and the application of in silico models for categorization and prioritization of data-poor ingredients for further screening. Based on the workflow developed in this study, 4 high priority, 18 medium priority, and 2 low priority substances were identified for further assessment.

The Chicken Egg Genotoxicity Assay (CEGA) is an avian egg-based model that utilizes the livers of developing chicken embryo-fetuses to assess the ability of chemicals to produce direct DNA damage. The main goal of the study was to evaluate target tissue exposure and metabolism in the CEGA to assess its suitability as a biologically relevant new approach methodology (NAM) for detecting the genotoxic potential of chemicals. An imaging study using two-photon excitation microscopy after the administration of a fluorescent dye (acridine orange) verified that chemicals following administration into the air sac of the fertilized chicken egg reach the target organ, liver. A metabolism study using liquid chromatography with high resolution mass spectrometry (LC/MS), conducted after the administration of benzo(a)pyrene (B(a)P) according to the CEGA protocol, confirmed the formation of sufficient amounts of reactive metabolite(s) responsible for the genotoxic effects of a parent compound upon reaching the target tissue. Moreover, an RNA sequencing study revealed that B(a)P in embryo-fetal chicken livers significantly upregulated several genes responsible for the activity of the CYP1A1 enzyme, which is critical for the bioactivation of B(a)P. These findings, along with the previously reported DNA damage (i.e., DNA adducts and single-strand breaks) produced by B(a)P in CEGA, support sufficient target tissue exposure to B(a)P and the ability of avian fetal livers to bioactivate B(a)P to a reactive intermediate. Overall, the findings in the study support the conclusion that the CEGA can be considered a robust potential alternative to the animal testing strategy for assessing the genotoxic potential of chemicals.

Adverse outcome pathways (AOPs) provide a framework to organize and weigh evidence linking molecular interactions of toxicants in cells to adverse outcomes relevant to risk assessment or regulatory decision-making. Applying this framework facilitates the interpretation of data produced using new test methods. We used an existing AOP (AOP #296) that describes how oxidative DNA damage leads to mutations and chromosomal aberrations to develop an integrated testing strategy to evaluate whether a chemical operates through this pathway. We exposed human TK6 cells to increasing concentrations of 4-nitroquinoline 1-oxide (4NQO), a tobacco mimetic that causes oxidative DNA damage, in a time-series design. We measured oxidative DNA damage and strand breaks using the high-throughput CometChip assay with and without formamidopyrimidine DNA glycosylase (Fpg), alongside analyses of micronucleus (MN) frequency by flow cytometry, and mutations by error-corrected sequencing (duplex sequencing—DS). Our analysis shows how these methods can be combined to quantify 4NQO-induced, concentration- and time-dependent increases in: (a) oxidative DNA damage (occurred early and at low concentrations); (b) strand breaks (remained elevated to 6 h post-exposure); (c) MN frequency (at 24 h); (d) mutation frequency (at 48 h); and (e) C > A transversions consistent with expected substitutions induced by oxidative DNA lesions. The time series shows the repair of oxidative DNA damage with persistent strand breaks remaining at 6 h. Overall, we provide an example of an AOP-informed testing strategy and contribute to the quantitative understanding of AOP #296. We also demonstrate the value of DS as an effective approach for mutagenicity assessment.

The benchmark dose (BMD) approach constitutes the most effective and pragmatic strategy for the derivation of a point of departure (PoD) for comparative potency analysis, risk assessment, and regulatory decision-making. There is considerable controversy regarding the most appropriate benchmark response (BMR) for genotoxicity endpoints. This work employed the Slob (2017) Effect Size (ES) theory to define robust BMR values for the in vivo transgenic rodent (TGR) and Pig-a mutagenicity endpoints. An extensive database of dose–response data was prepared and curated; BMD analyses were used to determine endpoint-specific maxima (i.e., parameter c) and within-group variance (i.e., var). Detailed analyses investigated the dependence of var on experimental factors such as tissue, administration route, treatment duration, and post-exposure tissue sampling time. The overall lack of influence of these experimental factors on var permitted the determination of typical values for the endpoints investigated. Typical var for the TGR endpoint is 0.19; the value for the Pig-a endpoint is 0.29. Endpoint-specific var values were used to calculate endpoint-specific BMR values; the values are 47% for TGR and 60% for Pig-a. Endpoint-specific BMR values were also calculated using the trimmed distribution of study-specific standard deviation (SD) values for concurrent controls. Those analyses yielded endpoint-specific BMR values for the TGR and Pig-a endpoints of 33% and 58%, respectively. Considering the results obtained, and the in vivo genetic toxicity BMR values noted in the literature, we recommend a BMR of 50% for in vivo mutagenicity endpoints. The value can be employed to interpret mutagenicity dose–response data in a risk assessment context.