scholarly journals p53-Dependent DNA damage response sensitive to editing-defective tRNA synthetase in zebrafish

2016 ◽  
Vol 113 (30) ◽  
pp. 8460-8465 ◽  
Author(s):  
Youngzee Song ◽  
Yi Shi ◽  
Tristan M. Carland ◽  
Shanshan Lian ◽  
Tomoyuki Sasaki ◽  
...  
Keyword(s):  
Dna Damage ◽  
Life Span ◽  
Morphological Changes ◽  
Critical Role ◽  
Trna Synthetase ◽  
Trna Synthetases ◽  
Downstream Signaling ◽  
Cycle Arrest ◽  
Normal Life Span ◽  
Transient Overexpression

Brain and heart pathologies are caused by editing defects of transfer RNA (tRNA) synthetases, which preserve genetic code fidelity by removing incorrect amino acids misattached to tRNAs. To extend understanding of the broader impact of synthetase editing reactions on organismal homeostasis, and based on effects in bacteria ostensibly from small amounts of mistranslation of components of the replication apparatus, we investigated the sensitivity to editing of the vertebrate genome. We show here that in zebrafish embryos, transient overexpression of editing-defective valyl-tRNA synthetase (ValRSED) activated DNA break-responsive H2AX and p53-responsive downstream proteins, such as cyclin-dependent kinase (CDK) inhibitor p21, which promotes cell-cycle arrest at DNA damage checkpoints, and Gadd45 and p53R2, with pivotal roles in DNA repair. In contrast, the response of these proteins to expression of ValRSED was abolished in p53-deficient fish. The p53-activated downstream signaling events correlated with suppression of abnormal morphological changes caused by the editing defect and, in adults, reversed a shortened life span (followed for 2 y). Conversely, with normal editing activities, p53-deficient fish have a normal life span and few morphological changes. Whole-fish deep sequencing showed genomic mutations associated with the editing defect. We suggest that the sensitivity of p53 to expression of an editing-defective tRNA synthetase has a critical role in promoting genome integrity and organismal homeostasis.

scholarly journals F-box protein FBXO31 directs degradation of MDM2 to facilitate p53-mediated growth arrest following genotoxic stress

2015 ◽  
Vol 112 (28) ◽  
pp. 8632-8637 ◽  
Author(s):  
Sunil K. Malonia ◽  
Parul Dutta ◽  
Manas Kumar Santra ◽  
Michael R. Green
Keyword(s):  
Dna Damage ◽  
Tumor Suppressor ◽  
Critical Role ◽  
Growth Arrest ◽  
Genotoxic Stress ◽  
26S Proteasome ◽  
Negative Regulator ◽  
Induce Cell Cycle Arrest ◽  
Cycle Arrest ◽  
F Box Protein

The tumor suppressor p53 plays a critical role in maintaining genomic stability. In response to genotoxic stress, p53 levels increase and induce cell-cycle arrest, senescence, or apoptosis, thereby preventing replication of damaged DNA. In unstressed cells, p53 is maintained at a low level. The major negative regulator of p53 is MDM2, an E3 ubiquitin ligase that directly interacts with p53 and promotes its polyubiquitination, leading to the subsequent destruction of p53 by the 26S proteasome. Following DNA damage, MDM2 is degraded rapidly, resulting in increased p53 stability. Because of the important role of MDM2 in modulating p53 function, it is critical to understand how MDM2 levels are regulated. Here we show that the F-box protein FBXO31, a candidate tumor suppressor encoded in 16q24.3 for which there is loss of heterozygosity in various solid tumors, is responsible for promoting MDM2 degradation. Following genotoxic stress, FBXO31 is phosphorylated by the DNA damage serine/threonine kinase ATM, resulting in increased levels of FBXO31. FBXO31 then interacts with and directs the degradation of MDM2, which is dependent on phosphorylation of MDM2 by ATM. FBXO31-mediated loss of MDM2 leads to elevated levels of p53, resulting in growth arrest. In cells depleted of FBXO31, MDM2 is not degraded and p53 levels do not increase following genotoxic stress. Thus, FBXO31 is essential for the classic robust increase in p53 levels following DNA damage.

scholarly journals Assessment of the Influence of 5-fluorouracil on the SMAD4 Gene Expression, Apoptosis induction and DNA Damage in the Human CACO-2 Cell Line

2021 ◽  
Author(s):  
Agnieszka Wosiak ◽  
Katarzyna Michalska ◽  
Jacek Pietrzak ◽  
Marek Mirowski ◽  
Ewa Balcerczak
Keyword(s):  
Gene Expression ◽  
Colorectal Cancer ◽  
Dna Damage ◽  
Cancer Cells ◽  
Downstream Signaling ◽  
Cycle Arrest ◽  
Low Concentrations ◽  
Late Stage Cancer ◽  
Colorectal Cancer Cells ◽  
Colorectal Cancer Patients

Abstract Colorectal cancer (CRC) is the third most common cancer in the world. There are two major distinct precursor lesion pathways: the traditional adenoma–carcinoma pathway leading to most cases CRC, and the serrated neoplasia pathway. SMAD4 gene is involved in adenoma–carcinoma pathway. The protein encoded by the SMAD4 gene is a key downstream signaling mediator in the TGFβ pathway. This pathway has tumor-suppressor functions, including cell-cycle arrest and apoptosis. Its activation in late-stage cancer can promote tumorigenesis, including metastasis and chemoresistance. This study aimed to evaluate the effect of 5-fluorouracil (5-FU) on viability of advanced colorectal cancer cells and establishing whether the test compound may have an effect on the expression level of the SMAD4 gene, DNA damage and apoptosis. Chemotherapy based on 5-FU is used as an adjuvant treatment in most colorectal cancer patients. The results obtained in the study showed that the use of 5-FU in low concentrations may not have a therapeutic effect, and may also influence drug resistance in cancer cells. Moreover, it has been shown that by using 5-FU at higher concentrations and prolonging the exposure time, SMAD4 gene expression is significantly increased which may have an impact on the effectiveness of the therapy.

scholarly journals Anticancer Imidazoacridinone C-1311 is Effective in Androgen-Dependent and Androgen-Independent Prostate Cancer Cells

Biomedicines ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 292 ◽  
Author(s):  
Magdalena Niemira ◽  
Barbara Borowa-Mazgaj ◽  
Samuel B. Bader ◽  
Adrianna Moszyńska ◽  
Marcin Ratajewski ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Dna Damage ◽  
Cell Cycle Progression ◽  
Target Genes ◽  
Critical Role ◽  
Specific Antigen ◽  
Transcriptional Response ◽  
Downstream Signaling ◽  
Induced Apoptosis ◽  
Androgen Independent

The androgen receptor (AR) plays a critical role in prostate cancer (PCa) development and metastasis. Thus, blocking AR activity and its downstream signaling constitutes a major strategy for PCa treatment. Here, we report on the potent anti-PCa activity of a small-molecule imidazoacridinone, C-1311. In AR-positive PCa cells, C-1311 was found to inhibit the transcriptional activity of AR, uncovering a novel mechanism that may be relevant for its anticancer effect. Mechanistically, C-1311 decreased the AR binding to the prostate-specific antigen (PSA) promoter, reduced the PSA protein level, and, as shown by transcriptome sequencing, downregulated numerous AR target genes. Importantly, AR-negative PCa cells were also sensitive to C-1311, suggesting a promising efficacy in the androgen-independent PCa sub-type. Irrespective of AR status, C-1311 induced DNA damage, arrested cell cycle progression, and induced apoptosis. RNA sequencing indicated significant differences in the transcriptional response to C-1311 between the PCa cells. Gene ontology analysis showed that in AR-dependent PCa cells, C-1311 mainly affected the DNA damage response pathways. In contrast, in AR-independent PCa cells, C-1311 targeted the cellular metabolism and inhibited the genes regulating glycolysis and gluconeogenesis. Together, these results indicate that C-1311 warrants further development for the treatment of PCa.

scholarly journals Pds1p, an inhibitor of anaphase in budding yeast, plays a critical role in the APC and checkpoint pathway(s).

1996 ◽  
Vol 133 (1) ◽  
pp. 99-110 ◽  
Author(s):  
A Yamamoto ◽  
V Guacci ◽  
D Koshland
Keyword(s):  
Cell Cycle ◽  
Dna Damage ◽  
Gamma Irradiation ◽  
Critical Role ◽  
Dna Damage Checkpoint ◽  
Microtubule Inhibitors ◽  
Cycle Arrest ◽  
Isolation And Characterization ◽  
Checkpoint Pathway ◽  
Cycle Regulation

We report the isolation and characterization of pds1 mutants in Saccharomyces cerevisiae. The initial pds1-1 allele was identified by its inviability after transient exposure to microtubule inhibitors and its precocious dissociation of sister chromatids in the presence of these microtubule inhibitors. These findings suggest that pds1 mutants might be defective in anaphase arrest that normally is imposed by a spindle-damage checkpoint. To further examine a role for Pds1p in anaphase arrest, we compared the cell cycle arrest of pds1 mutants and PDS1 cells after: (a) the inactivation of Cdc16p or Cdc23p, two proteins that are required for the degradation of mitotic cyclins and are putative components of the yeast anaphase promoting complex (APC); (b) the inactivation of Cdc20p, another protein implicated in the degradation of mitotic cyclins; and (c) the inactivation of Cdc13 protein or gamma irradiation, two circumstances that induce a DNA-damage checkpoint. Under all these conditions, anaphase is inhibited in PDS1 cells but not in pds1 mutants. From these results we suggest that Pds1 protein is an anaphase inhibitor in PDS1 cells but not in pds1 mutants. From these results we suggest that Pds1 protein is an anaphase inhibitor that plays a critical role in the control of anaphase by both APC and checkpoints. We also show that pds1 mutants exit mitosis and initiate new rounds of cell division after gamma irradiation and Cdc13p inactivation but no after nocodazole-treatment or inactivation of Cdc16p, Cdc20p or Cdc23p function. Therefore, in the DNA-damage checkpoint, Pds1p is required for the inhibition of cytokinesis and DNA replication as well as anaphase. The role of Pds1 protein in anaphase inhibition and general cell cycle regulation is discussed.

scholarly journals Interplay between genotoxic factors formaldehyde and UV-B exacerbates genome instability in Arabidopsis

2021 ◽  
Author(s):  
Yu Wang ◽  
Jinzheng WANG ◽  
Qiang Lv ◽  
Yi-Kun He
Keyword(s):  
Dna Damage ◽  
Genome Stability ◽  
Genome Instability ◽  
Critical Role ◽  
Genotoxic Stress ◽  
Cycle Arrest ◽  
Ros Accumulation ◽  
Genotoxic Factors ◽  
Living Organisms ◽  
Alcohol Dehydrogenase 2

Maintenance of genome stability is quintessential feature for all living organisms. The simplest aldehyde formaldehyde and UV-B radiation, two environmental toxic factors, cause DNA damage, affect genome stability, subsequently growth and development across kingdoms. However, the interrelationship of genotoxicity caused by formaldehyde and UV-B remains fragmented in plants. Here, we show that mutants lacking one aldehyde detoxifying enzyme, alcohol dehydrogenase 2 (ADH2, also named GSNOR/FALDH), are hypersensitive to low dosage UV-B radiation or UV-B radiation-mimetic chemical in seedling and root growth. The defects are not caused by the alteration of UV-B sensing, secondary metabolites flavonoid accumulation, or ROS accumulation, rather are UV-B-induced genotoxicity. Increased DNA damage response genes and comet assay tail, cell cycle arrest upon exposure to UV-B provide direct evidence for DNA damage in gsnor mutant. Pharmacological analyses show that the susceptibility to genotoxic stresses is caused by the increased DNA crosslink which results from the enhanced endogenous formaldehyde in gsnor while UV-B promotes the production of formaldehyde. This implies formaldehyde clearance through GSNOR plays a critical role in response to environmental genotoxic stress and interplay between formaldehyde and UV-B exacerbates genome instability.

scholarly journals Moderate hyperoxia induces senescence in developing human lung fibroblasts

2019 ◽  
Vol 317 (5) ◽  
pp. L525-L536 ◽  
Author(s):  
Kai You ◽  
Pavan Parikh ◽  
Karl Khandalavala ◽  
Sarah A. Wicher ◽  
Logan Manlove ◽  
...  
Keyword(s):  
Dna Damage ◽  
Er Stress ◽  
Morphological Changes ◽  
Fetal Lung ◽  
Positive Control ◽  
Lung Fibroblasts ◽  
Cycle Arrest ◽  
Tnf Α ◽  
M Phase ◽  
Human Fetal Lung

Hyperoxia exposure in premature infants increases the risk of subsequent lung diseases, such as asthma and bronchopulmonary dysplasia. Fibroblasts help maintain bronchial and alveolar integrity. Thus, understanding mechanisms by which hyperoxia influences fibroblasts is critical. Cellular senescence is increasingly recognized as important to the pathophysiology of multiple diseases. We hypothesized that clinically relevant moderate hyperoxia (<50% O2) induces senescence in developing fibroblasts. Using primary human fetal lung fibroblasts, we investigated effects of 40% O2 on senescence, endoplasmic reticulum (ER) stress, and autophagy pathways. Fibroblasts were exposed to 21% or 40% O2 for 7 days with etoposide as a positive control to induce senescence, evaluated by morphological changes, β-galactosidase activity, and DNA damage markers. Senescence-associated secretory phenotype (SASP) profile of inflammatory and profibrotic markers was further assessed. Hyperoxia decreased proliferation but increased cell size. SA-β-gal activity and DNA damage response, cell cycle arrest in G2/M phase, and marked upregulation of phosphorylated p53 and p21 were noted. Reduced autophagy was noted with hyperoxia. mRNA expression of proinflammatory and profibrotic factors (TNF-α, IL-1, IL-8, MMP3) was elevated by hyperoxia or etoposide. Hyperoxia increased several SASP factors (PAI-1, IL1-α, IL1-β, IL-6, LAP, TNF-α). The secretome of senescent fibroblasts promoted extracellular matrix formation by naïve fibroblasts. Overall, we demonstrate that moderate hyperoxia enhances senescence in primary human fetal lung fibroblasts with reduced autophagy but not enhanced ER stress. The resulting SASP is profibrotic and may contribute to abnormal repair in the lung following hyperoxia.

scholarly journals MDM2/X Inhibitors as Radiosensitizers for Glioblastoma Targeted Therapy

2021 ◽  
Vol 11 ◽  
Author(s):  
Xanthene Miles ◽  
Charlot Vandevoorde ◽  
Alistair Hunter ◽  
Julie Bolcaen
Keyword(s):  
Dna Damage ◽  
Therapeutic Interventions ◽  
Cellular Damage ◽  
Current Status ◽  
Cancer Therapies ◽  
Downstream Signaling ◽  
Cycle Arrest ◽  
Radiation Induced ◽  
P53 Activation

Inhibition of the MDM2/X-p53 interaction is recognized as a potential anti-cancer strategy, including the treatment of glioblastoma (GB). In response to cellular stressors, such as DNA damage, the tumor suppression protein p53 is activated and responds by mediating cellular damage through DNA repair, cell cycle arrest and apoptosis. Hence, p53 activation plays a central role in cell survival and the effectiveness of cancer therapies. Alterations and reduced activity of p53 occur in 25-30% of primary GB tumors, but this number increases drastically to 60-70% in secondary GB. As a result, reactivating p53 is suggested as a treatment strategy, either by using targeted molecules to convert the mutant p53 back to its wild type form or by using MDM2 and MDMX (also known as MDM4) inhibitors. MDM2 down regulates p53 activity via ubiquitin-dependent degradation and is amplified or overexpressed in 14% of GB cases. Thus, suppression of MDM2 offers an opportunity for urgently needed new therapeutic interventions for GB. Numerous small molecule MDM2 inhibitors are currently undergoing clinical evaluation, either as monotherapy or in combination with chemotherapy and/or other targeted agents. In addition, considering the major role of both p53 and MDM2 in the downstream signaling response to radiation-induced DNA damage, the combination of MDM2 inhibitors with radiation may offer a valuable therapeutic radiosensitizing approach for GB therapy. This review covers the role of MDM2/X in cancer and more specifically in GB, followed by the rationale for the potential radiosensitizing effect of MDM2 inhibition. Finally, the current status of MDM2/X inhibition and p53 activation for the treatment of GB is given.

Glutamyl and Glutaminyl-tRNA Synthetases Are a Promising Target for the Design of Threonine-Producing Strain

2019 ◽  
Vol 35 (6) ◽  
pp. 39-50
Author(s):  
T.V. Yuzbashev ◽  
A.S. Fedorov ◽  
F.V. Bondarenko ◽  
A.S. Savchenko ◽  
T.V. Vybornaya ◽  
...  
Keyword(s):  
Biomass Accumulation ◽  
Trna Synthetase ◽  
Temperature Sensitive ◽  
Original Strain ◽  
Trna Synthetases ◽  
Resource Center ◽  
Promising Target ◽  
The Russian Federation ◽  
Increase In Productivity ◽  
Culture Growth

The present work describes an approach that improves the properties of the strain producing L-threonine via the reduction in the biomass accumulation during fermentation. Glutamyl- and glutaminyl-tRNA synthetases were chosen as targets. Mutants carrying temperature-sensitive alleles were obtained. It was shown that the used system caused the suppression of the function of tRNA synthetases which led to a rapid arrest of the culture growth, and an increase in productivity and yield of the L-threonine synthesis. One of the temperature-sensitive strains was used to obtain under non-permissive conditions of mutants with the suppressed above phenotype. Some of these mutants accumulate less biomass and produce by 10-12% more threonine than the original strain. Escherichia coli, producing strain, threonine, aminoacyl-tRNA synthetase, ts-mutation This work was supported by the Ministry of Science and Higher Education of the Russian Federation (project code RFMEFI61017X0011), and it was carried out using the equipment of the National Bio-Resource Center All-Russian Collection of Industrial Microorganisms, NRC «Kurchatov Institute» - GosNIIgenetika.

Oxidative Stress, Ocular Disease and Diabetes Retinopathy

2019 ◽  
Vol 24 (40) ◽  
pp. 4726-4741 ◽  
Author(s):  
Orathai Tangvarasittichai ◽  
Surapon Tangvarasittichai
Keyword(s):  
Oxidative Stress ◽  
Dna Damage ◽  
Cell Death ◽  
Protein Modification ◽  
Morphological Changes ◽  
Corneal Dystrophy ◽  
Age Related Macular Degeneration ◽  
Ocular Diseases ◽  
Retinal Light Damage ◽  
Age Related

Background: Oxidative stress is caused by free radicals or oxidant productions, including lipid peroxidation, protein modification, DNA damage and apoptosis or cell death and results in cellular degeneration and neurodegeneration from damage to macromolecules. Results: Accumulation of the DNA damage (8HOdG) products and the end products of LPO (including aldehyde, diene, triene conjugates and Schiff’s bases) were noted in the research studies. Significantly higher levels of these products in comparison with the controls were observed. Oxidative stress induced changes to ocular cells and tissues. Typical changes include ECM accumulation, cell dysfunction, cell death, advanced senescence, disarrangement or rearrangement of the cytoskeleton and released inflammatory cytokines. It is involved in ocular diseases, including keratoconus, Fuchs endothelial corneal dystrophy, and granular corneal dystrophy type 2, cataract, age-related macular degeneration, primary open-angle glaucoma, retinal light damage, and retinopathy of prematurity. These ocular diseases are the cause of irreversible blindness worldwide. Conclusions: Oxidative stress, inflammation and autophagy are implicated in biochemical and morphological changes in these ocular tissues. The development of therapy is a major target for the management care of these ocular diseases.

A Novel Camptothecin Derivative 3j Inhibits Nsclc Proliferation Via Induction of Cell Cycle Arrest By Topo I-Mediated DNA Damage

2019 ◽  
Vol 19 (3) ◽  
pp. 365-374 ◽  
Author(s):  
Yang Liu ◽  
Jingyin Zhang ◽  
Shuyun Feng ◽  
Tingli Zhao ◽  
Zhengzheng Li ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Flow Cytometry ◽  
Dna Damage ◽  
Cyclin D ◽  
Dna Relaxation ◽  
Cycle Arrest ◽  
H460 Cell ◽  
H1975 Cell

Objective: The aim of this study is to investigate the inhibitory effect of camptothecin derivative 3j on Non-Small Cell Lung Cancer (NSCLCs) cells and the potential anti-tumor mechanisms. Background: Camptothecin compounds are considered as the third largest natural drugs which are widely investigated in the world and they suffered restriction because of serious toxicity, such as hemorrhagic cystitis and bone marrow suppression. Methods: Using cell proliferation assay and S180 tumor mice model, a series of 20(S)-O-substituted benzoyl 7- ethylcamptothecin compounds were screened and evaluated the antitumor activities in vitro and in vivo. Camptothecin derivative 3j was selected for further study using flow cytometry in NSCLCs cells. Cell cycle related protein cyclin A2, CDK2, cyclin D and cyclin E were detected by Western Blot. Then, computer molecular docking was used to confirm the interaction between 3j and Topo I. Also, DNA relaxation assay and alkaline comet assay were used to investigate the mechanism of 3j on DNA damage. Results: Our results demonstrated that camptothecin derivative 3j showed a greater antitumor effect in eleven 20(S)-O-substituted benzoyl 7-ethylcamptothecin compounds in vitro and in vivo. The IC50 of 3j was 1.54± 0.41 µM lower than irinotecan with an IC50 of 13.86±0.80 µM in NCI-H460 cell, which was reduced by 8 fold. In NCI-H1975 cell, the IC50 of 3j was 1.87±0.23 µM lower than irinotecan (IC50±SD, 5.35±0.38 µM), dropped by 1.8 fold. Flow cytometry analysis revealed that 3j induced significant accumulation in a dose-dependent manner. After 24h of 3j (10 µM) treatment, the percentage of NCI-H460 cell in S-phase significantly increased (to 93.54 ± 4.4%) compared with control cells (31.67 ± 3.4%). Similarly, the percentage of NCI-H1975 cell in Sphase significantly increased (to 83.99 ± 2.4%) compared with control cells (34.45 ± 3.9%) after treatment with 10µM of 3j. Moreover, increased levels of cyclin A2, CDK2, and decreased levels of cyclin D, cyclin E further confirmed that cell cycle arrest was induced by 3j. Furthermore, molecular docking studies suggested that 3j interacted with Topo I-DNA and DNA-relaxation assay simultaneously confirmed that 3j suppressed the activity of Topo I. Research on the mechanism showed that 3j exhibited anti-tumour activity via activating the DNA damage response pathway and suppressing the repair pathway in NSCLC cells. Conclusion: Novel camptothecin derivative 3j has been demonstrated as a promising antitumor agent and remains to be assessed in further studies.

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