• Journal of Genetic Medicine
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• 제13권1호
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• pp.1-13
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• 2016

Although some mutations are beneficial and are the driving force behind evolution, it is important to maintain DNA integrity and stability because it contains genetic information. However, in the oxygen-rich environment we live in, the DNA molecule is under constant threat from endogenous or exogenous insults. DNA damage could trigger the DNA damage response (DDR), which involves DNA repair, the regulation of cell cycle checkpoints, and the induction of programmed cell death or senescence. Dysregulation of these physiological responses to DNA damage causes developmental defects, neurological defects, premature aging, infertility, immune system defects, and tumors in humans. Some human syndromes are characterized by unique neurological phenotypes including microcephaly, mental retardation, ataxia, neurodegeneration, and neuropathy, suggesting a direct link between genomic instability resulting from defective DDR and neuropathology. In this review, rare human genetic disorders related to abnormal DDR and damage repair with neural defects will be discussed.

• Asian-Australasian Journal of Animal Sciences
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• 제19권3호
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• pp.335-340
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• 2006

A large number of toxicological substances and pharmacological and physical agents can cause reproductive intervention at the cellular and molecular level. The present study was designed to assess the effect of mercury ($HgCl_2$) at 50 to $550{\mu}M$ concentration ranges, in vitro, on the sperm membrane and DNA integrity, viability, and acrosomal status of normal bull spermatozoa. The samples were processed for sperm analyses using semen-diluting fluid (PBS, pH 7.2). We recorded a sharp increase in the lipid peroxidation/LPO rate; the highest was at $550{\mu}M$ mercury concentration, indicating a deleterious effect of mercury on the sperm membrane intactness. There was also a strong negative correlation between LPO rate and % viable spermatozoa (R = 0.987, p<0.001). Data obtained from a comet assay technique revealed that mercury is capable of inducing DNA breaks in the sperm nuclei. Interestingly, 92% of DNA breaks were double-stranded. The correlation between LPO rate and % DNA breaks was 0.984. Performing the gelatin test indicates that mercury is able to alter the integrity of acrosomal membranes showing an abnormal acrosome reaction. In this regard, a strong link was found between LPO rate and % halos (R = 0.990, p<0.001). Collectively, mercury proved to be a potent oxidant in the category of environmental factors affecting bull spermatozoa. Hence, considering the wide spread use of mercury and its compounds, these metals should be regarded with more concern.

• BMB Reports
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• 제52권8호
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• pp.475-481
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• 2019

The evolution of genome editing technology based on CRISPR (clustered regularly interspaced short palindromic repeats) system has led to a paradigm shift in biological research. CRISPR/Cas9-guide RNA complexes enable rapid and efficient genome editing in mammalian cells. This system induces double-stranded DNA breaks (DSBs) at target sites and most DNA breakages induce mutations as small insertions or deletions (indels) by non-homologous end joining (NHEJ) repair pathway. However, for more precise correction as knock-in or replacement of DNA base pairs, using the homology-directed repair (HDR) pathway is essential. Until now, many trials have greatly enhanced knock-in or substitution efficiency by increasing HDR efficiency, or newly developed methods such as Base Editors (BEs). However, accuracy remains unsatisfactory. In this review, we summarize studies to overcome the limitations of HDR using the CRISPR system and discuss future direction.

• BMB Reports
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• 제56권2호
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• pp.102-107
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• 2023

Genome editing using CRISPR-associated technology is widely used to modify the genomes rapidly and efficiently on specific DNA double-strand breaks (DSBs) induced by Cas9 endonuclease. However, despite swift advance in Cas9 engineering, structural basis of Cas9-recognition and cleavage complex remains unclear. Proper assembly of this complex correlates to effective Cas9 activity, leading to high efficacy of genome editing events. Here, we develop a CRISPR/Cas9-RAD51 plasmid constitutively expressing RAD51, which can bind to single-stranded DNA for DSB repair. We show that the efficiency of CRISPR-mediated genome editing can be significantly improved by expressing RAD51, responsible for DSB repair via homologous recombination (HR), in both gene knock-out and knock-in processes. In cells with CRISPR/Cas9-RAD51 plasmid, expression of the target genes (cohesin SMC3 and GAPDH) was reduced by more than 1.9-fold compared to the CRISPR/Cas9 plasmid for knock-out of genes. Furthermore, CRISPR/Cas9-RAD51 enhanced the knock-in efficiency of DsRed donor DNA. Thus, the CRISPR/Cas9-RAD51 system is useful for applications requiring precise and efficient genome edits not accessible to HR-deficient cell genome editing and for developing CRISPR/Cas9-mediated knockout technology.

• 한국발생생물학회지:발생과생식
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• 제20권2호
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• pp.141-147
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• 2016

Rad51 is a key component of homologous recombination (HR) to repair DNA double-strand breaks and it forms Rad51 recombinase filaments of broken single-stranded DNA to promote HR. In addition to its role in DNA repair and cell cycle progression, Rad51 contributes to the reprogramming process during the generation of induced pluripotent stem cells. In light of this, we performed reprogramming experiments to examine the effect of co-expression of Rad51 and four reprogramming factors, Oct4, Sox2, Klf4, and c-Myc, on the reprogramming efficiency. Co-expression of Rad51 significantly increased the numbers of alkaline phosphatase-positive colonies and embryonic stem cell-like colonies during the process of reprogramming. Co-expression ofRad51 significantly increased the expression of epithelial markers at an early stage of reprogramming compared with control cells. Phosphorylated histone H2AX (${\gamma}H2AX$), which initiates the DNA double-strand break repair system, was highly accumulated in reprogramming intermediates upon co-expression of Rad51. This study identified a novel role of Rad51 in enhancing the reprogramming efficiency, possibly by facilitating mesenchymal-to-epithelial transition and by regulating a DNA damage repair pathway during the early phase of the reprogramming process.

• 한국동물생명공학회지
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• 제34권3호
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• pp.197-204
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• 2019

This study was investigated to test whether the zygote recognized the topoisomerase II beta (TOP2B) mediated DNA fragmentation in epididymal spermatozoa or the nuclease degradation in vas deferens spermatozoa by testing for the presence of gammaH2AX (γH2AX). The γH2AX is phosphorylation of histone protein H2AX on serine 139 occurs at sites flanking DNA double-stranded breaks (DSBs). The presence of γH2AX in the pronuclei of mouse zygotes which were injected with DNA broke epididymal spermatozoa was tested by immunohistochemistry at 5 and 9 h post fertilization, respectively. Paternal pronuclei that arose from epididymal spermatozoa treated with divalent cations did not stain for γH2AX at 5 h. On the other hand, in embryos injected with vas deferences spermatozoa that had been treated with divalent cations, γH2AX was only present in paternal pronuclei, and not the maternal pronuclei at 5 h. Interestingly, both pronuclei stained positively for γH2AX for all treatments and controls at 9 h after sperm injection. In conclusion, the embryos recognize DNA that is damaged by nuclease, but not by TOP2B because H2AX in phosphorylated in paternal pronuclei resulting from spermatozoa treated with fragmented DNA from vas deferens spermatozoa treated with divalent cations, but not from epididymal spermatozoa treated the same way.

• Clinical and Experimental Pediatrics
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• 제48권12호
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• pp.1295-1309
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• 2005

Nowadays, the nutritional deficits are rarely seen in Korea. However, an increased availability of the highly palatable energy dense, nutrient-poor foods increases the risks of obesity and deficits of vitamins and minerals in the general population. Also, optimum intake of vitamins and minerals, which varies with age and genetic back ground, might not suffice the poor, young, obese, and elderly people. Young girls and individuals participating in weight reductions and aesthetic components are prone to micronutrient deficiencies because they restrict food intake and specific micronutrient rich foods. An inadequate intake of vitamins or minerals is associated with reduced physical performance and exercise capacity, increased obesity, decreased cognitive function, increased DNA damages such as single- and double-stranded breaks or oxidative DNA lesions, and accelerated aging process and increased neuronal damages with mitochondrial oxidative decay. Most of these deleterious effects of the deficit could be prevented by a one tablet of multivitamins with a good balanced diet. High dose B vitamins are frequently administered to overcome the metabolic inadequacy to the people with the less functional enzymes with increased Km values for their coenzymes due to the single gene mutation or due to the single nucleotide polymorphisms. And some certain antioxidant vitamins are also used in large quantities to overcome the oxidative stress and to repair the damages. In this review, new nutritional concepts of some vitamins and minerals, which are widely used and useful for the children, will be discussed.

• Journal of Acupuncture Research
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• 제18권1호
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• pp.88-99
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• 2001

Objectives : This study was performed to determine if Orostachys japonicus A. Berger aquacupuncture (OjB) provides the protective effect against the loss of celi viability and DNA damage induced by oxidant in renal proximal tubular cells. Methods : The cell viability was evaluated by a MTT reduction assay and DNA damage was estimated by measuring double stranded DNA breaks in opossum kidney (OK) cells, an established proximal tubular cell line. Lipid peroxidation was determined by measuring malondialdehyde (MDA), a product of lipid peroxidation. Results : $H_2O_2$ increased the loss of cell viability in a time-dependent manner, which were prevented by 0.1% OjB. The protective effect of OjB was dose-dependent over concentration range of 0.05-0.5%. $H_2O_2$ caused ATP depletion and DNA damage, which were prevented by OjB and the hydrogen peroxide scavenger catalase. The loss of cell viability by $H_2O_2$ was not affected by the antioxidant DPPD, but lipid peroxidation by the oxidant was completely inhibited by DPPD. Conclusions : These data suggest that $H_2O_2$-induced death results from a lipid peroxidation-independent mechanism and the protective effect of OjB is not associated with its antioxidant activity.

• Journal of Microbiology
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• 제37권4호
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• pp.248-255
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• 1999

We have analyzed the MRE3/REC114 gene of Saccharomyces cerevisiae, previously detected in isolation of mutants defective in meiotic recombination. We cloned the MRE3/REC114 gene by complementation of the meiotic recombination defect and it has been mapped to chormosome XIII. The DNA sequence analysis revealed that the MRE3 gene is identical to the REC114 gene. The upstream region of the MRE3/REC114 gene contains a T_4C site, a URS (upstream repression sequence) and a TR (T-rich) box-like sequence, which reside upstream of many meiotic genes. Coincidentally, northern blot analysis indicated that the three sizes of MRE3/REC114 transcripts, 3.4, 1.4 and 1.2 kb, are induced in meiosis. A less abundant transcript of 1.4 kb is detected in both mitotic and meiotic cells, suggesting that it is needed in mitosis as well as meiosis. To examine the role of the MRE3/REC114 gene, we constructed mre3 disruption mutants. Strains carrying an insertion or null deletion of the MRE3/REC114 gene showed slow growth in nutrient medium and the doubling time of these cells increased approximately by 2-fond compared to the wild-type strain. Moreover, the deletion mutant (${\delta}$mre3) displayed no meiotically induced recombination and no viable spores. The mre3/rec114 spore lethality can be suppressed by spo13, a mutation that causes cells to bypass reductional division. The double-stranded breaks (DSBs) which are involved in initiation of meiotic recombination were not detected in the analysis of meiotic chromosomal DNA from the mre3/rec114 disruptant. From these results we suggest that the MRE3/REC114 gene product is essential in normal growth and in early meiotic stages involved in meiotic recombination.

• Asian Pacific Journal of Cancer Prevention
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• 제16권18호
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• pp.8503-8512
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• 2016

The purpose of this study was to provide a detailed explanation of the mechanism of bisanthracycline, WP 631 in comparison to doxorubicin (DOX), a first generation anthracycline, currently the most widely used pharmaceutical in clinical oncology. Experiments were performed in SKOV-3 ovarian cancer cells which are otherwise resistant to standard drugs such as cis-platinum and adriamycin. As attention was focused on the ability of WP 631 to induce apoptosis, this was examined using a double staining method with Annexin V and propidium iodide probes, with measurement of the level of intracellular calcium ions and cytosolic cytochrome c. The western blotting technique was performed to confirm PARP cleavage. We also investigated the involvement of caspase activation and DNA degradation (comet assay and immunocytochemical detection of phosphorylated H2AX histones) in the development of apoptotic events. WP 631 demonstrated significantly higher effectiveness as a pro-apoptotic drug than DOX. This was evident in the higher levels of markers of apoptosis, such as the externalization of phosphatidylserine and the elevated level of cytochrome c. An extension of incubation time led to an increase in intracellular calcium levels after treatment with DOX. Lower changes in the calcium content were associated with the influence of WP 631. DOX led to the activation of all tested caspases, 8, 9 and 3, whereas WP 631 only induced an increase in caspase 8 activity after 24h of treatment and consequently led to the cleavage of PARP. The lack of active caspase 3 had no outcome on the single and double-stranded DNA breaks. The obtained results show that WP 631 was considerably more genotoxic towards the investigated cell line than DOX. This effect was especially visible after longer times of incubation. The above detailed studies indicate that WP 631 generates early apoptosis and cell death independent of caspase-3, detected at relatively late time points. The observed differences in the mechanisms of the action of WP631 and DOX suggest that this bisanthracycline can be an effective alternative in ovarian cancer treatment.