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Aging Jan 2021The naked mole rat (NMR), is the longest-living rodent species, and is extraordinarily resistant to cancer and aging-related diseases. The molecular basis for these...
The naked mole rat (NMR), is the longest-living rodent species, and is extraordinarily resistant to cancer and aging-related diseases. The molecular basis for these unique phenotypic traits of the NMR is under extensive research. However, the role of regulated cell death (RCD) in the longevity and the protection from cancer in the NMR is still largely unknown. RCD is a mechanism restricting the proliferation of damaged or premalignant cells, which counteracts aging and oncotransformation. In this study, DNA damage-induced cell death in NMR fibroblasts was investigated in comparison to RCD in fibroblasts from . The effects of methyl methanesulfonate, 5-fluorouracil, and etoposide in both cell types were examined using contemporary cell death analyses. Skin fibroblasts from were found to be more resistant to the action of DNA damaging agents compared to fibroblasts from . Strikingly, our results revealed that NMR cells also exhibit a limited apoptotic response and seem to undergo regulated necrosis. Taken together, this study provides new insights into the mechanisms of cell death in NMR expanding our understanding of longevity, and it paves the way towards the development of innovative therapeutic approaches.
Topics: Animals; Cells, Cultured; DNA Damage; Fibroblasts; Longevity; Methyl Methanesulfonate; Mice; Mole Rats; Regulated Cell Death
PubMed: 33510044
DOI: 10.18632/aging.202577 -
ACS Omega Jun 2022Ammonium salt derivatives with a neopentyl moiety are remarkably stable against Hofmann elimination, but the neopentyl moiety slows nucleophilic substitution,...
Ammonium salt derivatives with a neopentyl moiety are remarkably stable against Hofmann elimination, but the neopentyl moiety slows nucleophilic substitution, complicating their synthesis. To identify the best leaving group for the synthesis of the ammonium salts, we prepared six 1,1,1-tris(X-methyl)ethane derivatives, where X is chloride, bromide, iodide, methanesulfonate, -toluenesulfonate, and trifluoromethanesulfonate (triflate), and studied the kinetics of their reactions with sodium, cesium, or tetramethylammonium azide in deuterated dimethylsulfoxide (DMSO) at 100 °C by NMR spectroscopy. Iodide and bromide were found to be more reactive than -toluenesulfonate and methanesulfonate. As expected, the best leaving group for nucleophilic substitution was triflate. Despite the usual high reactivity and instability of primary alkyl triflates, neopentyl triflate can be used as a stable but sufficiently reactive reactant for nucleophilic substitution on neopentyl skeletons.
PubMed: 35721974
DOI: 10.1021/acsomega.2c01965 -
The New Phytologist Mar 2023The endonuclease methyl methanesulfonate and UV-sensitive protein 81 (MUS81) has been reported to participate in DNA repair during mitosis and meiosis. However, the...
The endonuclease methyl methanesulfonate and UV-sensitive protein 81 (MUS81) has been reported to participate in DNA repair during mitosis and meiosis. However, the exact meiotic function of MUS81 in rice remains unclear. Here, we use a combination of physiological, cytological, and genetic approaches to provide evidence that MUS81 functions in atypical recombination intermediate resolution rather than crossover designation in rice. Cytological and genetic analysis revealed that the total chiasma numbers in mus81 mutants were indistinguishable from wild-type. The numbers of HEI10 foci (the sites of interference-sensitive crossovers) in mus81 were also similar to that of wild-type. Moreover, disruption of MUS81 in msh5 or msh4 msh5 background did not further decrease chiasmata frequency, suggesting that rice MUS81 did not function in crossover designation. Mutation of FANCM and ZEP1 could enhance recombination frequency. Unexpectedly, chromosome fragments and bridges were frequently observed in mus81 zep1 and mus81 fancm, illustrating that MUS81 may resolve atypical recombination intermediates. Taken together, our data suggest that MUS81 contributes little to crossover designation but plays a crucial role in the resolution of atypical meiotic intermediates by working together with other anti-crossover factors.
Topics: Crossing Over, Genetic; DNA-Binding Proteins; Oryza; Meiosis; Endonucleases
PubMed: 36495065
DOI: 10.1111/nph.18668 -
International Journal of Molecular... Sep 2021Here, we present a new lux-biosensor based on for detecting of DNA-tropic and oxidative stress-causing agents. Hybrid plasmids pNK-DinC, pNK-AlkA, and pNK-MrgA have...
Here, we present a new lux-biosensor based on for detecting of DNA-tropic and oxidative stress-causing agents. Hybrid plasmids pNK-DinC, pNK-AlkA, and pNK-MrgA have been constructed, in which the reporter genes are transcribed from the stress-inducible promoters of : the SOS promoter P, the methylation-specific response promoter P, and the oxidative stress promoter P. The luminescence of based biosensors specifically increases in response to the appearance in the environment of such common toxicants as mitomycin C, methyl methanesulfonate, and HO. Comparison with -based lux-biosensors, where the promoters P, P, and P were used, showed generally similar characteristics. However, for P, a higher response amplitude was observed, and for P, on the contrary, both the amplitude and the range of detectable toxicant concentrations were decreased. P and P showed increased sensitivity to the genotoxic effects of the 2,2'-bis(bicyclo [2.2.1] heptane) compound, which is a promising propellant, compared to -based lux-biosensors. The obtained biosensors are applicable for detection of toxicants introduced into soil. Such bacillary biosensors can be used to study the differences in the mechanisms of toxicity against Gram-positive and Gram-negative bacteria.
Topics: Bacillus subtilis; Bacterial Proteins; Biosensing Techniques; Microorganisms, Genetically-Modified; Plasmids; Promoter Regions, Genetic
PubMed: 34502476
DOI: 10.3390/ijms22179571 -
Nucleic Acids Research Dec 2022UV-DDB is a DNA damage recognition protein recently discovered to participate in the removal of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxoG) by stimulating multiple...
UV-DDB is a DNA damage recognition protein recently discovered to participate in the removal of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxoG) by stimulating multiple steps of base excision repair (BER). In this study, we examined whether UV-DDB has a wider role in BER besides oxidized bases and found it has specificity for two known DNA substrates of alkyladenine glycosylase (AAG)/N-methylpurine DNA glycosylase (MPG): 1, N6-ethenoadenine (ϵA) and hypoxanthine. Gel mobility shift assays show that UV-DDB recognizes these two lesions 4-5 times better than non-damaged DNA. Biochemical studies indicated that UV-DDB stimulated AAG activity on both substrates by 4- to 5-fold. Native gels indicated UV-DDB forms a transient complex with AAG to help facilitate release of AAG from the abasic site product. Single molecule experiments confirmed the interaction and showed that UV-DDB can act to displace AAG from abasic sites. Cells when treated with methyl methanesulfonate resulted in foci containing AAG and UV-DDB that developed over the course of several hours after treatment. While colocalization did not reach 100%, foci containing AAG and UV-DDB reached a maximum at three hours post treatment. Together these data indicate that UV-DDB plays an important role in facilitating the repair of AAG substrates.
Topics: DNA Glycosylases; DNA Damage; DNA Repair; DNA
PubMed: 36511855
DOI: 10.1093/nar/gkac1145 -
Data in Brief Dec 2023Toxicological analysis of the effects of natural compounds is frequently mandated to assess their safety. In addition to more simple cellular systems, more complex...
Toxicological analysis of the effects of natural compounds is frequently mandated to assess their safety. In addition to more simple cellular systems, more complex biological systems can be used to evaluate toxicity. This dataset is comprised of bright-field microscopy images of chicken-embryo blood cells, a complex biological model that recapitulates several features found in human organisms, including circulation in blood stream and biodistribution to different organs. In the presented collection of blood smear images, cells were exposed to the flavonoid quercetin, and the two mutagens methyl methanesulfonate (MMS) and cadmium chloride (CdCl). models offer a unique opportunity to investigate the effects of various substances, pathogens, or cancer treatments on developing embryos, providing valuable insights into potential risks and therapeutic strategies. In toxicology, models allow for early detection of harmful compounds and their impact on embryonic development, aiding in the assessment of environmental hazards. In immunology, these models offer a controlled system to explore the developing immune responses and the interaction between pathogens and host defenses. Additionally, models are instrumental in oncology research as they enable the study of tumor development and response to therapies in a dynamic, rapidly developing environment. Thus, these versatile models play a crucial role in advancing our understanding of complex biological processes and guiding the development of safer therapeutics and interventions. The data presented here can aid in understanding the potential toxic effects of these substances on hematopoiesis and the overall health of the developing organism. Moreover, the large dataset of blood smear images can serve as a resource for training machine learning algorithms to automatically detect and classify blood cells, provided that specific optimized conditions such as image magnification and background light are maintained for comparison. This can lead to the development of automated tools for blood cell analysis, which can be useful in research. Moreover, the data is amenable to the use as teaching and learning resource for histology and developmental biology.
PubMed: 37876742
DOI: 10.1016/j.dib.2023.109673 -
BMC Plant Biology Dec 2022MicroRNAs (miRNAs) and other epigenetic modifications play fundamental roles in all eukaryotic biological processes. DNA damage repair is a key process for maintaining...
BACKGROUND
MicroRNAs (miRNAs) and other epigenetic modifications play fundamental roles in all eukaryotic biological processes. DNA damage repair is a key process for maintaining the genomic integrity of different organisms exposed to diverse stresses. However, the reaction of miRNAs in the DNA damage repair process is unclear.
RESULTS
In this study, we found that the simultaneous mutation of zinc finger DNA 3'-phosphoesterase (ZDP) and AP endonuclease 2 (APE2), two genes that play overlapping roles in active DNA demethylation and base excision repair (BER), led to genome-wide alteration of miRNAs. The transcripts of newly transcribed miRNA-encoding genes (MIRs) decreased significantly in zdp/ape2, indicating that the mutation of ZDP and APE2 affected the accumulation of miRNAs at the transcriptional level. In addition, the introduction of base damage with the DNA-alkylating reagent methyl methanesulfonate (MMS) accelerated the reduction of miRNAs in zdp/ape2. Further mutation of FORMAMIDOPYRIMIDINE DNA GLYCOSYLASE (FPG), a bifunctional DNA glycosylase/lyase, rescued the accumulation of miRNAs in zdp/ape2, suggesting that the accumulation of DNA damage repair intermediates induced the transcriptional repression of miRNAs.
CONCLUSIONS
Our investigation indicates that the accumulation of DNA damage repair intermediates inhibit miRNAs accumulation by inhibiting MIR transcriptions.
Topics: Arabidopsis; DNA Damage; DNA Repair; Transcription, Genetic; MicroRNAs; Endonucleases; Arabidopsis Proteins
PubMed: 36503409
DOI: 10.1186/s12870-022-03951-9 -
Frontiers in Molecular Neuroscience 2022Retinitis pigmentosa (RP) is a group of neurodegenerative retinopathies causing blindness due to progressive and irreversible photoreceptor cell death. The alkylating...
INTRODUCTION
Retinitis pigmentosa (RP) is a group of neurodegenerative retinopathies causing blindness due to progressive and irreversible photoreceptor cell death. The alkylating agent methyl methanesulfonate (MMS) can induce selective photoreceptor cell death, which is used to establish RP animal models. MMS induces DNA base damage by adding alkyl groups to DNA, and epigenetic modifications influence DNA damage response. Here, we aimed to explore the relationship between DNA methylation and DNA damage response in dying photoreceptors of RP.
METHODS
The mouse RP model was established by a single intraperitoneal injection of MMS. The retinal structure and function were assessed by H&E, OCT, TUNEL, and ERG at several time points. The expression of DNA methylation regulators was assessed by qPCR and Western blot. DNMT inhibitor 5-aza-dC was applied to inhibit the activity of DNA methyltransferases and improve the retinal photoreceptor damage.
RESULTS
The outer nuclear layer (ONL) and IS/OS layer were significantly thinner and the retinal function was impaired after MMS treatment. The cell death was mainly located in the ONL. The retinal damage induced by MMS was accompanied by hyperexpression of DNMT3A/3B. The application of DNMT inhibitor 5-aza-dC could suppress the expression level of DNMT3A/3B, resulting in the remission of MMS-induced photoreceptor cell damage. The ONL and IS/OS layers were thicker than that of the control group, and the retinal function was partially restored. This protective effect of 5-aza-dC was associated with the down-regulated expression of DNMT3A/3B.
CONCLUSION
These findings identified a functional role of DNMT3A/3B in MMS-induced photoreceptor cell damage and provided novel evidence to support DNMTs as potential therapeutic targets in retinal degenerative diseases.Graphical Abstract.
PubMed: 36704326
DOI: 10.3389/fnmol.2022.1057365 -
Frontiers in Neuroscience 2022The retina is an important visual organ, which is responsible for receiving light signals and transmitting them to the optic nerve center step by step. The retina...
The retina is an important visual organ, which is responsible for receiving light signals and transmitting them to the optic nerve center step by step. The retina contains a variety of cells, among which photoreceptor cells receive light signals and convert them into nerve signals, and are mainly responsible for light and dark vision. Retinal degeneration is mainly the degeneration of photoreceptor cells, and retinitis pigmentosa (RP) is characterized by rod degeneration followed by cone degeneration. So far, there is still a lack of effective drugs to treat RP. Here, we established a stable RP model by tail vein injection of methyl methanesulfonate to study the mechanism of retinal photoreceptor degeneration. Mechanistic target of rapamycin (mTOR) is located in the central pathway of growth and energy metabolism and changes in a variety of diseases in response to pathological changes. We found that the mTOR was activated in this model. Therefore, the inhibitor of mTOR, rapamycin was used to suppress the expression of mTOR and interfere with photoreceptor degeneration. Electroretinogram assay showed that the function of mice retina was improved. Hematoxylin and eosin staining results displayed that retinal photoreceptor thickness and morphology were improved. Also, the autophagy in rapamycin group was activated, which revealed that rapamycin may protect the retinal photoreceptor by inhibiting mTOR and then activating autophagy.
PubMed: 35295093
DOI: 10.3389/fnins.2022.846584 -
Frontiers in Genetics 2022Methyl methanesulfonate-sensitivity protein 22-like (MMS22L) is crucial in protecting genome integrity during DNA replication by preventing DNA damage and maintaining...
Methyl methanesulfonate-sensitivity protein 22-like (MMS22L) is crucial in protecting genome integrity during DNA replication by preventing DNA damage and maintaining efficient homologous recombination. However, the role of MMS22L in human cancers remains unclear. Here, we reported the landscape of MMS22L using multi-omics data and identified the relationship between the MMS22L status and pan-cancer prognosis. In addition, the correlation of MMS22L mRNA expression levels with tumor mutational burden, microsatellite instability, homologous recombination deficiency, and loss of heterozygosity in pan-cancer was also described in this study. Furthermore, this study was the first to characterize the relationship between mRNA expression of MMS22L and immune cell infiltration in the tumor microenvironment in human cancer. Concurrently, this study explored the crucial role of MMS22L in different immunotherapy cohorts through current immunotherapy experiments. Eventually, we investigated the role of MMS22L in hepatocellular carcinoma (HCC). The results demonstrated that MMS22L is widely expressed in multiple HCC cell lines, and our results emphasized that MMS22L was involved in HCC progression and affects the prognosis of patients with HCC through multiple independent validation cohorts. Collectively, our findings reveal the essential role of MMS22L as a tumor-regulating gene in human cancers while further emphasizing its feasibility as a novel molecular marker in HCC. These findings provide an essential reference for the study of MMS22L in tumors.
PubMed: 36276962
DOI: 10.3389/fgene.2022.1025970