Aging and oxidative stress alter DNA repair mechanisms in male germ cells of superoxide dismutase-1 null mice

Author(s):  
Paulina Nguyen-Powanda ◽  
Bernard Robaire

Abstract The efficiency of antioxidant defense system decreases with aging, thus resulting in high levels of reactive oxygen species (ROS) and DNA damage in spermatozoa. This damage can lead to genetic disorders in the offspring. There are limited studies investigating the effects of the total loss of antioxidants, such as superoxide dismutase-1 (SOD1), in male germ cells as they progress through spermatogenesis. In this study, we evaluated the effects of aging and removing SOD1 (in male germ cells of SOD1-null (Sod1−/−) mice) in order to determine the potential mechanism(s) of DNA damage in these cells. Immunohistochemical analysis showed an increase in lipid peroxidation and DNA damage in the germ cells of aged wild-type (WT) and Sod1−/− mice of all age. Immunostaining of OGG1, a marker of base excision repair (BER), increased in aged WT and young Sod1−/− mice. In contrast, immunostaining intensity of LIGIV and RAD51, markers of non-homologous end-joining (NHEJ) and homologous recombination (HR), respectively, decreased in aged and Sod1−/− mice. Gene expression analysis showed similar results with altered mRNA expression of these key DNA repair transcripts in pachytene spermatocytes and round spermatids of aged and Sod1−/− mice. Our study indicates that DNA repair pathway markers of BER, NHEJ, and HR are differentially regulated as a function of aging and oxidative stress in spermatocytes and spermatids, and aging enhances the repair response to increased oxidative DNA damage, whereas impairments in other DNA repair mechanisms may contribute to the increase in DNA damage caused by aging and the loss of SOD1.

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Jusciele Brogin Moreli ◽  
Janine Hertzog Santos ◽  
Clarissa Ribeiro Rocha ◽  
Débora Cristina Damasceno ◽  
Glilciane Morceli ◽  
...  

The increased production of reactive oxygen species (ROS) plays a key role in pathogenesis of diabetic complications. ROS are generated by exogenous and endogenous factors such as during hyperglycemia. When ROS production exceeds the detoxification and scavenging capacity of the cell, oxidative stress ensues. Oxidative stress induces DNA damage and when DNA damage exceeds the cellular capacity to repair it, the accumulation of errors can overwhelm the cell resulting in cell death or fixation of genome mutations that can be transmitted to future cell generations. These mutations can lead to and/or play a role in cancer development. This review aims at (i) understanding the types and consequences of DNA damage during hyperglycemic pregnancy; (ii) identifying the biological role of DNA repair during pregnancy, and (iii) proposing clinical interventions to maintain genome integrity. While hyperglycemia can damage the maternal genetic material, the impact of hyperglycemia on fetal cells is still unclear. DNA repair mechanisms may be important to prevent the deleterious effects of hyperglycemia both in mother and in fetus DNA and, as such, prevent the development of diseases in adulthood. Hence, in clinical practice, maternal glycemic control may represent an important point of intervention to prevent the deleterious effects of maternal hyperglycemia to DNA.


Cancers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 504
Author(s):  
Takayuki Saitoh ◽  
Tsukasa Oda

Multiple myeloma (MM) is an incurable plasma cell malignancy characterized by genomic instability. MM cells present various forms of genetic instability, including chromosomal instability, microsatellite instability, and base-pair alterations, as well as changes in chromosome number. The tumor microenvironment and an abnormal DNA repair function affect genetic instability in this disease. In addition, states of the tumor microenvironment itself, such as inflammation and hypoxia, influence the DNA damage response, which includes DNA repair mechanisms, cell cycle checkpoints, and apoptotic pathways. Unrepaired DNA damage in tumor cells has been shown to exacerbate genomic instability and aberrant features that enable MM progression and drug resistance. This review provides an overview of the DNA repair pathways, with a special focus on their function in MM, and discusses the role of the tumor microenvironment in governing DNA repair mechanisms.


2020 ◽  
Vol 22 (1) ◽  
pp. 6
Author(s):  
Ievgeniia Gazo ◽  
Roman Franěk ◽  
Radek Šindelka ◽  
Ievgen Lebeda ◽  
Sahana Shivaramu ◽  
...  

DNA damage caused by exogenous or endogenous factors is a common challenge for developing fish embryos. DNA damage repair (DDR) pathways help organisms minimize adverse effects of DNA alterations. In terms of DNA repair mechanisms, sturgeons represent a particularly interesting model due to their exceptional genome plasticity. Sterlet (Acipenser ruthenus) is a relatively small species of sturgeon. The goal of this study was to assess the sensitivity of sterlet embryos to model genotoxicants (camptothecin, etoposide, and benzo[a]pyrene), and to assess DDR responses. We assessed the effects of genotoxicants on embryo survival, hatching rate, DNA fragmentation, gene expression, and phosphorylation of H2AX and ATM kinase. Exposure of sterlet embryos to 1 µM benzo[a]pyrene induced low levels of DNA damage accompanied by ATM phosphorylation and xpc gene expression. Conversely, 20 µM etoposide exposure induced DNA damage without activation of known DDR pathways. Effects of 10 nM camptothecin on embryo development were stage-specific, with early stages, before gastrulation, being most sensitive. Overall, this study provides foundational information for future investigation of sterlet DDR pathways.


2019 ◽  
Vol 20 (5) ◽  
pp. 1146 ◽  
Author(s):  
Marta Włodarczyk ◽  
Grażyna Nowicka

Obesity has been recognized to increase the risk of such diseases as cardiovascular diseases, diabetes, and cancer. It indicates that obesity can impact genome stability. Oxidative stress and inflammation, commonly occurring in obesity, can induce DNA damage and inhibit DNA repair mechanisms. Accumulation of DNA damage can lead to an enhanced mutation rate and can alter gene expression resulting in disturbances in cell metabolism. Obesity-associated DNA damage can promote cancer growth by favoring cancer cell proliferation and migration, and resistance to apoptosis. Estimation of the DNA damage and/or disturbances in DNA repair could be potentially useful in the risk assessment and prevention of obesity-associated metabolic disorders as well as cancers. DNA damage in people with obesity appears to be reversible and both weight loss and improvement of dietary habits and diet composition can affect genome stability.


Reproduction ◽  
2001 ◽  
pp. 31-39 ◽  
Author(s):  
WM Baarends ◽  
R van der Laan ◽  
JA Grootegoed

In mammals, there is a complex and intriguing relationship between DNA repair and gametogenesis. DNA repair mechanisms are involved not only in the repair of different types of DNA damage in developing germline cells, but also take part in the meiotic recombination process. Furthermore, the DNA repair mechanisms should tolerate mutations occurring during gametogenesis, to a limited extent. In the present review, several gametogenic aspects of DNA mismatch repair, homologous recombination repair and postreplication repair are discussed. In addition, the role of DNA damage-induced cell cycle checkpoint control is considered briefly. It appears that many genes encoding proteins that take part in DNA repair mechanisms show enhanced or specialized expression during mammalian gametogenesis, and several gene knockout mouse models show male or female infertility. On the basis of such knowledge and models, future experiments may provide more information about the precise relationship between DNA repair, chromatin dynamics, and genomic stability versus instability during gametogenesis.


Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 723-723
Author(s):  
Michele Cea ◽  
Antonia Cagnetta ◽  
Aditya Munshi ◽  
Yu-Tzu Tai ◽  
Teru Hideshima ◽  
...  

Abstract Abstract 723 Background: Multiple myeloma (MM) is a clonal malignancy of plasma cells with hallmark genetic instability resulting in large-scale changes at diagnosis, as well as further evolution contributing to disease progression. Inhibition of DNA repair mechanisms leads to significant reduction in acquisition of new genetic changes and associated progression of MM. Mammalian sirtuins are class III NAD+-dependent deacetylases emerging as innovative proteins involved in multiple pathways, including genome maintenance. Methods: A panel of 18 MM cell lines, both sensitive and resistant to conventional and novel anti-MM therapies, was used in the study. The antitumor effect of a pan-sirtuins inhibitor, Nicotinamide (Nam), alone and combined with DNA-damaging agents, was investigated by CTG assay and Annexin-V/propidium iodide staining. Mechanistic studies were performed with thymidine incorporation, Western-blotting, lentivirus-mediated shRNAs and immunofluorescence assay. Analysis of DNA DSB repair was done using chromosomally integrated reporter constructs, followed by cytometer analysis. Results: We analyzed an Affymetrix GeneChip (GSE6477) array of patient MM cells (n=162) compared with normal plasma cells, and found that transcript levels of two nuclear sirtuins (SIRT6 and SIRT7) were significantly higher in monoclonal gammopathy of undetermined significance (MGUS), smoldering MM, active MM, and relapsed MM compared with normal plasma cells. Importantly, protein analysis confirmed increased nuclear levels of these deacetylases in MM cell lines, including those resistant to DNA-damaging agents (MM.1R, LR-5, Dox40), as well as in patient CD138+ MM cells compared to PBMCs from healthy donors. Next we evaluated the functional role of these Sirtuins in MM cells by using loss of function approaches with RNAi. SIRT6 and SIRT7 silencing by knockdown reduced MM cell proliferation compared with control scrambled cells, with only a modest induction of cytotoxicity. We also examined the effects of Nam on DNA-damage response signaling triggered by conventional anti-MM agents melphalan and doxorubicin. Nam treatment did not appreciably affect MM cell viability; however, pretreatment with Nam impaired DNA double-strand breaks (DSBs) repair as well as DNA repair mechanisms triggered by conventional DNA damaging agents, evidenced by γH2AX and RPA phosphorylation, respectively. Consistent with these findings, Nam-pretreated MM cells formed fewer RAD51 foci in response to Doxorubicin and Melphalan, thereby conferring sensitivity to these agents. Importantly, this sensitizing effect was also observed in MM cells resistant to doxorubicin (RPMI-Doxo40) or melphalan (LR5), indicating that Nam increases chemosensitivity in both drug-sensitive and –resistant MM cells. Similarly, lentivirus-mediated shRNA knockdown of SIRT-6 and −7 sensitized MM cells to melphalan and doxorubicin. Finally, both chemical and genetic approaches improved the efficiency of DNA DSB repair mechanisms (Homologous and non-Homologous end-joining Recombination) in MM cell lines containing chromosomally integrated green fluorescent protein-based reporter constructs. Ongoing in vivo experiments are assessing how the chemical susceptibility of SIRT6 and/or 7-deficient cells can be exploited therapeutically. Conclusion: Our study demonstrates a link between nuclear sirtuins and DNA instability in MM cells, providing the basis for incorporation of inhibitors of these SIRTs into innovative anti-MM therapeutic approaches. Disclosures: Munshi: Celgene: Consultancy; Millenium: Consultancy; Merck: Consultancy; Onyx: Consultancy.


2003 ◽  
Vol 84 (6) ◽  
pp. 1275-1287 ◽  
Author(s):  
Alejandro A. Romero ◽  
Stephane R. Gross ◽  
Ke-Yi Cheng ◽  
Noriko K. Goldsmith ◽  
Herbert M. Geller

2021 ◽  
Vol 37 (2) ◽  
Author(s):  
Irfan Ullah ◽  
Muhammad Zahid ◽  
Muhammad Jawad ◽  
Aatik Arsh

Objective: To assess the DNA damage and oxidative stress among traffic conductors and coal miners. Methods: An analytical cross-sectional survey was conducted in Karak, Pakistan from March to October 2019. A total of 240 individuals participated in the study with an age range between 17 to 55 years. Among the total sample, 60 participants had exposure to traffic pollution while 60 were mine workers. Two control groups, consisting of 60 individuals each, were also recruited for comparison with the two exposure groups. Comet assay protocols were performed for assessing DNA damage and oxidative stress (length of DNA tail, levels of Superoxide Dismutase (SOD), Malondialdehyde (MDA) and Glutathione (GSH)). Data was analyzed using T-test on statistix 9.0 software. Results: The DNA tail length in traffic conductors ranged from 26.83-30.55µm (Mean=28.69 µm while their control group had DNA tail length of 7.98-9.26µm (Mean= 8.62). There was significant difference (P <0.001) between exposure and control group. The DNA length recorded in coal mine workers and their control group was ranged from 29.06-31.26µm (Mean=30.16µm) and 9.42-10.22µm (Mean=9.82), respectively. There was significant difference (P <0.001) between the two groups. As compared to control groups, both exposure groups have high levels of Superoxide Dismutase and Malondialdehyde and low levels of Glutathione. The finding was statistically significant (P <0.001). Conclusion: Increased inhalational exposure to air pollutants via working in traffic or coal mines can impose higher oxidative stress and DNA damage among workers as compared to the general population. doi: https://doi.org/10.12669/pjms.37.2.2848 How to cite this:Ullah I, Zahid M, Jawad M, Arsh A. Assessment of DNA damage and oxidative stress among traffic conductors and coal miners. Pak J Med Sci. 2021;37(2):---------. doi: https://doi.org/10.12669/pjms.37.2.2848 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


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