• BMB Reports
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• 제47권5호
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• pp.249-255
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• 2014

Polo-like kinase-1 (Plk1) belongs to a family of serine-threonine kinases and plays a critical role in mitotic progression. Plk1 involves in the initiation of mitosis, centrosome maturation, bipolar spindle formation, and cytokinesis, well-reported as traditional functions of Plk1. In this review, we discuss the role of Plk1 during DNA damage response beyond the functions in mitotsis. When DNA is damaged in cells under various stress conditions, the checkpoint mechanism is activated to allow cells to have enough time for repair. When damage is repaired, cells progress continuously their division, which is called checkpoint recovery. If damage is too severe to repair, cells undergo apoptotic pathway. If damage is not completely repaired, cells undergo a process called checkpoint adaptation, and resume cell division cycle with damaged DNA. Plk1 targets and regulates many key factors in the process of damage response, and we deal with these subjects in this review.

• BMB Reports
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• 제54권2호
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• pp.98-105
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• 2021

The clustered regularly interspaced short palindromic repeats (CRISPR) system is a family of DNA sequences originally discovered as a type of acquired immunity in prokaryotes such as bacteria and archaea. In many CRISPR systems, the functional ribonucleoproteins (RNPs) are composed of CRISPR protein and guide RNAs. They selectively bind and cleave specific target DNAs or RNAs, based on sequences complementary to the guide RNA. The specific targeted cleavage of the nucleic acids by CRISPR has been broadly utilized in genome editing methods. In the process of genome editing of eukaryotic cells, CRISPR-mediated DNA double-strand breaks (DSB) at specific genomic loci activate the endogenous DNA repair systems and induce mutations at the target sites with high efficiencies. Two of the major endogenous DNA repair machineries are non-homologous end joining (NHEJ) and homology-directed repair (HDR). In case of DSB, the two repair pathways operate in competition, resulting in several possible outcomes including deletions, insertions, and substitutions. Due to the inherent stochasticity of DSB-based genome editing methods, it was difficult to achieve defined single-base changes without unanticipated random mutation patterns. In order to overcome the heterogeneity in DSB-mediated genome editing, novel methods have been developed to incorporate precise single-base level changes without inducing DSB. The approaches utilized catalytically compromised CRISPR in conjunction with base-modifying enzymes and DNA polymerases, to accomplish highly efficient and precise genome editing of single and multiple bases. In this review, we introduce some of the advances in single-base level CRISPR genome editing methods and their applications.

• Asian Pacific Journal of Cancer Prevention
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• 제16권12호
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• pp.4803-4812
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• 2015

Chronic alcohol and tobacco abuse plays a crucial role in the development of different liver associated disorders. Intake promotes the generation of reactive oxygen species within hepatic cells exposing their DNA to continuous oxidative stress which finally leads to DNA damage. However in response to such damage an entangled protective repair machinery comprising different repair proteins like ATM, ATR, H2AX, MRN complex becomes activated. Under abnormal conditions the excessive reactive oxygen species generation results in genetic predisposition of various genes (as ADH, ALDH, CYP2E1, GSTT1, GSTP1 and GSTM1) involved in xenobiotic metabolic pathways, associated with susceptibility to different liver related diseases such as fibrosis, cirrhosis and hepatocellular carcinoma. There is increasing evidence that the inflammatory process is inherently associated with many different cancer types, including hepatocellular carcinomas. The generated reactive oxygen species can also activate or repress epigenetic elements such as chromatin remodeling, non-coding RNAs (micro-RNAs), DNA (de) methylation and histone modification that affect gene expression, hence leading to various disorders. The present review provides comprehensive knowledge of different molecular mechanisms involved in gene polymorphism and their possible association with alcohol and tobacco consumption. The article also showcases the necessity of identifying novel diagnostic biomarkers for early cancer risk assessment among alcohol and tobacco users.

• 대한두경부종양학회지
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• 제22권2호
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• pp.117-122
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• 2006

Background and Objectives : Thyroid carcinoma is the sixth commonest cancer in Korea and the papillary carcinoma is the most common type(88%) of the malignant thyroid tumors. Bulky DNA adducts formed by the carcinogens are repaired by DNA repair process, but failure to repair this DNA damage can cause mutations in oncogenes and tumor suppressor genes resulting in tumor formation. The xeroderma pigmentosum group C(XPC) gene is essential for this repair procedure and the XPC-PolyAT(PAT) polymorphisms may alter DNA repair capacity(DRC) and genetic susceptibility to cancer. Subjects and Methods : In a case-control study of 113 Korean patients with pathologically diagnosed thyroid papillary carcinoma and 65 control subjects, we investigated the association between the three XPC-PAT gene polymorphisms and thyroid papillary cancer susceptibility. Results : The frequency of the variant XPC-PAT allele was lower in the cases(0.349) than in the controls (0.423), but the difference was not significant(p=0.140). Using logistic regression adjusting for age and sex, risk for thyroid papillary cancer was not increased in the XPC-PAT-/+ and XPC-PAT+/+ compared to XPCPAT-/-(adjusted overall odds ratio[95% confidence intervals;95%CI]=0.52[0.26-1.03] and 0.62 [0.22-1.75], respectively; trend test, p=0.167). Conclusion : There are no relationship between the XPC-PAT polymorphism and the risk of thyroid papillary carcinoma in Korean population. Based on our results, XPC-PAT polymorphism do not modulate genetic susceptibility to thyroid papillary cancer.

• Molecules and Cells
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• 제41권8호
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• pp.799-807
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• 2018

Emerging evidence has suggested that cellular crosstalk between RNF168 and poly(ADP-ribose) polymerase 1 (PARP1) contributes to the precise control of the DNA damage response (DDR). However, the direct and reciprocal functional link between them remains unclear. In this report, we identified that RNF168 ubiquitinates PARP1 via direct interaction and accelerates PARP1 degradation in the presence of poly (ADP-ribose) (PAR) chains, metabolites of activated PARP1. Through mass spectrometric analysis, we revealed that RNF168 ubiquitinated multiple lysine residues on PARP1 via K48-linked ubiquitin chain formation. Consistent with this, micro-irradiation-induced PARP1 accumulation at damaged chromatin was significantly increased by knockdown of endogenous RNF168. In addition, it was confirmed that abnormal changes of HR and HNEJ due to knockdown of RNF168 were restored by overexpression of WT RNF168 but not by reintroduction of mutants lacking E3 ligase activity or PAR binding ability. The comet assay also revealed that both PAR-binding and ubiquitin-conjugation activities are indispensable for the RNF168-mediated DNA repair process. Taken together, our results suggest that RNF168 acts as a counterpart of PARP1 in DDR and regulates the HR/NHEJ repair processes through the ubiquitination of PARP1.

• BMB Reports
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• 제40권3호
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• pp.432-438
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• 2007

V(D)J recombination, a site-specific gene rearrangement process occurring during the lymphocyte development, begins with DNA double strand breaks by two recombination activating gene products (RAG1/2) and finishes with the repair process by several proteins including DNA-dependent protein kinase (DNA-PK). In this report, we found that RAG2 was specifically phosphorylated by DNA-PK at the $365^{th}$ serine residue, and this phosphorylated RAG2 affected the V(D)J recombination activity in cells in the GFP expression-based assay. While the V(D)J recombination activity between wild-type RAG2 and mutant S365A RAG2 in the assay using a signal joint substrate was undistinguishable in DNA-PK deficient cells (M059J), the activity with wild-type RAG2 was largely increased in DNA-PK proficient cells (M059K) in comparison with mutant RAG2, suggesting that RAG2 phosphorylation by DNA-PK plays a crucial role in the signal joint formation during V(D)J recombination.

• 한국동물학회지
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• 제25권2호
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• pp.55-62
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• 1982

발생 12일째의 계배근세포를 약 7일간 배양하면서 자외선에 의한 절제회복, 광재활성 및 DNA 복제억제율을 조사하여 다음과 같은 결과를 얻었다. 자외선에 의한 절제회복은 계배근세포의 분화정도가 진행됨에 따라 감소하였으며, 이는 특히 자외선의 선량이 높을수록 뚜렷하였다. DNA 합성율은 분화가 진행된 세포일수록 현저히 감소하는 경향이었으며 각 분화단계에 따른 DNA 복제억제 현상은 배양 초기 세포인 경우 자외선 조사후 30분에서 1시간반 사이에서 가장 심하게 나타났고, 배양후기의 세포에서는 이러한 억제현상이 뚜렷하지 않았다. 또 배양 1일째 세포에서 광재활성에 의한 피리미딘 이량체의 감소율은 자외선 조사직후에 현저하였다가 그후 시간의 경과에 따른 차이는 보이지 않았다. 그러나, 절제회복만에 의한 이량체의 감소는 조사후 시간이 지남에 따라 서서히 감소하여 광재활성에 의한 이량체의 감소량과 비슷한 수준으로 접근하였다.

• 생물정신의학
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• 제5권2호
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• pp.219-226
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• 1998

Cytosine arabinoside(AraC) inhibits DNA synthesis and ${\beta}$-DNA polymerase, an enzyme involved in DNA repair. This, a potent antimitotic agent, is clinically used as an anticancer drug with side effect of severe neurotoxicity. Earlier reports suggested that inhibition of neuronal survival by AraC in sympathetic neuron may be due to the inhibition of a 2'-deoxycytidine-dependent process that is independent of DNA synthesis or repair and AraC induced a signal that is triggers a cascade of new mRNA and protein synthesis, leading to apoptotic cell death in cultured cerebellar granule cells. The present study would suggest whether caspase family(ICE/CED-3-like protease) involved in AraC-induced apoptosis pathway of PC12 cells. It was observed that treatment of PC12 cells with AraC led to decrease of viability by MTT assay and morphology changes, which did not suggest that AraC induced apoptosis in PC12 cells. The mRNA of caspase-1/caspase-3 were expressed in PC12 cells constitutively, and AraC did not activate caspase family. These results suggest that caspase-1/caspase-3 may not be required for AraC-induced cell death pathway in PC12 cells.

• Nutrition Research and Practice
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• 제3권3호
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• pp.185-191
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• 2009

The elevated level of circulating estradiol increases the risk of breast tumor development. To gain further insight into mechanisms involved in their actions, we investigated the molecular mechanisms of 4-hydroxyestradiol (4-$OHE_2$) to initiate and/or promote abnormal cell growth, and of $\alpha$- or $\gamma$-tocopherol to inhibit this process. MCF-10A, human breast epithelial cells were incubated with $0.1{\mu}M$ 4-$OHE_2$, either with or without $30{\mu}M$ tocopherols for 96 h. 4-$OHE_2$ caused the accumulation of intracellular ROS, while cellular GSH/GSSG ratio and MnSOD protein levels were decreased, indicating that there was an oxidative burden. 4-$OHE_2$ treatment also changed the levels of DNA repair proteins, BRCA1 and PARP-1. $\gamma$-Tocopherol suppressed the 4-$OHE_2$-induced increases in ROS, GSH/GSSG ratio, and MnSOD protein expression, while $\alpha$-tocopherol up-regulated BRCA1 and PARP-1 protein expression. In conclusion, 4-$OHE_2$ increases oxidative stress reducing the level of proteins related to DNA repair. Tocopherols suppressed oxidative stress by scavenging ROS or up-regulating DNA repair elements.

• Asian Pacific Journal of Cancer Prevention
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• 제14권9호
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• pp.5275-5279
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• 2013

Background: The XRCC1 (X-ray repair cross complimenting group-I) gene in BER (base excision repair) pathway is essential for DNA repair process. Polymorphisms in this gene are associated with variations in the repair efficiency which might predispose individuals to development of various cancers. Two variants of XRCC1gene (at codon 399), Gln/Gln and Arg/Gln, have been shown to be related to lowered DNA repair capacity and increased genomic instability in multiple studies. Hence our investigation focused on genotyping these variants to correlate with other multiple risk factors in lung cancer (NSCLC) patients since we hypothesized that these variants of the XRCC1 gene might influence disease susceptibility. Materials and Methods: We examined the frequency of the polymorphism in one hundred cases and an almost equal number of controls after recording their demographics with a structured questionnaire. Genomic DNA from blood samples was extracted for PCR studies, followed by RFLP to determine the variants. The significance of the data was statistically analyzed. Results: The three genotypes in cases and controls were Arg/Arg (40% and 54.45%); Gln/Gln (19% and 9.90%), and Arg/Gln (41.0% and 35.64%) respectively. Among these 3 genotypes, we found Gln/Gln and Arg/Gln to show association with lung cancer. Correlating these genotypes with several parameters, we also found that these two variants were associated with risk in males (p<0.05) and with smoking habits (p<0.05). In females Arg/Gln genotype showed association with stage of the disease (p=0.04). This is the first report in South Indian scenario where Arg399Gln genotypes were found to be associated with stage of the disease in females. Conclusions: It is concluded that XRCC1 genotypes Gln/Gln and Arg/Gln may influence cancer susceptibility in patients with smoking habits and these functional SNPs in XRCC1 gene may act as attractive candidate biomarkers in lung cancer for diagnosis and prognosis.