• BMB Reports
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• v.56 no.2
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• pp.108-113
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• 2023

Cohesin is a ring-shaped protein complex that comprises the SMC1, SMC3, and α-kleisin proteins, STAG1/2/3 subunits, and auxiliary factors. Cohesin participates in chromatin remodeling, chromosome segregation, DNA replication, and gene expression regulation during the cell cycle. Mitosis-specific α-kleisin factor RAD21 and meiosis-specific α-kleisin factor REC8 are expressed in embryonic stem cells (ESCs) to maintain pluripotency. Here, we demonstrated that RAD21 and REC8 were involved in maintaining genomic stability and modulating chromatin modification in murine ESCs. When the kleisin subunits were depleted, DNA repair genes were downregulated, thereby reducing cell viability and causing replication protein A (RPA) accumulation. This finding suggested that the repair of exposed single-stranded DNA was inefficient. Furthermore, the depletion of kleisin subunits induced DNA hypermethylation by upregulating DNA methylation proteins. Thus, we proposed that the cohesin complex plays two distinct roles in chromatin remodeling and genomic integrity to ensure the maintenance of pluripotency in ESCs.

• Molecules and Cells
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• v.46 no.2
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• pp.86-98
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• 2023

The genome is almost identical in all the cells of the body. However, the functions and morphologies of each cell are different, and the factors that determine them are the genes and proteins expressed in the cells. Over the past decades, studies on epigenetic information, such as DNA methylation, histone modifications, chromatin accessibility, and chromatin conformation have shown that these properties play a fundamental role in gene regulation. Furthermore, various diseases such as cancer have been found to be associated with epigenetic mechanisms. In this study, we summarized the biological properties of epigenetics and single-cell epigenomic profiling techniques, and discussed future challenges in the field of epigenetics.

• Korean Journal of Poultry Science
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• v.42 no.2
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• pp.109-116
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• 2015

Ogye rooster sperm chromatin status can be detected using well established sperm assays. In this paper, a simple and fast method to monitor rooster sperm chromatin status could be employed in field for assessment of chicken sperm quality. Using standard bright field microscope, Diff-Quik stains can be reproducibly, easily and routinely monitored with simple staining. The presence of abnormal chromatin staining of rooster sperm was determined by darker stain in head. In the fresh semen, the viabilities of three tested Ogye spermatozoa were 93.53%, 82.42% and 90.63% and normal chromatin rates were 87.96%, 74.25% and 85.10% respectively. However, after freezing, the rates of viability of thawed semen were reduced to 69.58%, 61.98% and 72.20% and normal chromatin rate also reduced to 58.91%, 48.49% and 63.34%. A significant correlation between live sperm and normal sperm nuclei was 0.875 in fresh semen and 0.513 in frozen semen. After incubation of sperm at $37^{\circ}C$ for 5min, the rates of viability, chromatin normality and sperm head activity were shown as $90.63{\pm}1.28%$, $82.44{\pm}8.09%$ and $66.68{\pm}10.29%$ in fresh semen. However, the rates of thawed semen were reduced to $67.92{\pm}7.55%$, $56.92{\pm}12.15%$ and 47.32{\pm}5.02%, respectively. The relationship between chromatin normality and sperm head movements in fresh and thawed semen were 0.564 and 0.540, respectively. With these results, the chicken sperm normality could be assessed by the Diff-Quik staining that could be used for chromatin status of sperm head and activated morphology of live spermatozoa, as a simple and rapid staining method.

• Journal of Applied Biological Chemistry
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• v.57 no.4
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• pp.379-386
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• 2014

Chromatin is an instructive DNA structure that can widely respond to external signals. An important change of chromatin is the modifications of histone for this regulation. There are accumulating lists of these modifications and the complexity of their action is gradually understood. It is evident that histone modifications play important roles in most biological processes that are involved in the expression or repression of DNA. The surface of nucleosomes is susceptible to multiplicity of modifications. Chromatin modifications can play either by eliminating chromatin contacts or by recruiting non-histone proteins to chromatin. Many of these regulations seem to be epigenetically inherited. Thus, histone modifications are closely correlated with many fundamental biological processes in animal, plant and microbial kingdoms. Failures of histone modification lead, in general, to defective chromosome condensation or decondensation, impeding many biological functions including development, maturation, and protection against various diseases.

• BMB Reports
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• v.48 no.12
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• pp.685-690
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• 2015

The eukaryotic genome is packed into chromatin, which is important for the genomic integrity and gene regulation. Chromatin structures are maintained through assembly and disassembly of nucleosomes catalyzed by histone chaperones. Asf1 (anti-silencing function 1) is a highly conserved histone chaperone that mediates histone transfer on/off DNA and promotes histone H3 lysine 56 acetylation at globular core domain of histone H3. To elucidate the role of Asf1 in the modulation of chromatin structure, we screened and identified small molecules that inhibit Asf1 and H3K56 acetylation without affecting other histone modifications. These pyrimidine-2,4,6-trione derivative molecules inhibited the nucleosome assembly mediated by Asf1 in vitro, and reduced the H3K56 acetylation in HeLa cells. Furthermore, production of HSV viral particles was reduced by these compounds. As Asf1 is implicated in genome integrity, cell proliferation, and cancer, current Asf1 inhibitor molecules may offer an opportunity for the therapeutic development for treatment of diseases.

• Reproductive and Developmental Biology
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• v.32 no.2
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• pp.127-133
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• 2008

The objective of this study was two folds: to investigate the relationship between paternal identification rate and sperm quality parameters such as motility and sperm chromatin structure assay after heterospermic insemination; to see if mutual complement between tests and development of useful technique to enhance the fertility in artificial insemination. In individual boar's fertilizing ability, 3 high fertility boars showed significantly high fertility (p<0.05) compared to 3 low fertility boars, but there was no difference in litter size between two groups. Sperm motility test in pooled and individual semen using computer assisted sperm analysis (CASA) revealed that no significant difference among boars. The high fertile boar showed tendency of low %Red (High red fluorescence/green+red fluorescence) in sperm chromatin structure assay (SCSA) but paternal identification rate from piglets did not differ after heterospermic insemination. The correlation coefficient between individual or pooled semen function test and farrowing rates were well correlated as follows: %Red with litter size (r= - 0.53, p=0.03); %Red with paternal identification rates (r=-0.51, p=0.03); paternal identification rates with litter size (r=0.57, p=0.02). These results indicate that sperm chromatin structure assay and sperm quality parameter test in pooled semen are useful method to predict and evaluate the fertilizing capacity after heterospermic insemination in boars.

• The Korean Journal of Cytopathology
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• v.18 no.1
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• pp.36-45
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• 2007

Objective : To identify key cytologic features for diagnosis of adenocarcinoma and morphologic differentiation from reactive/reparative respiratory epithelium. Study Design : The cytomorphologic features of 145 pulmonary cytology specimens (sputum and bronchial washing), which included 117 histologically proven adenocarcinomas and 28 non-neoplastic lesions, cytologically diagnosed as atypia and suspicious for malignancy (adenocarcinoma) were reviewed retrospectively. We analyzed 11 morphologic criteria in pulmonary cytologic specimens. Results: Over 110 of 117 cases of adenocarcinomas revealed nuclear membrane irregularities, non-cohesive cells, single atypical cells, moderate to markedly enlarged nuclei and an increased nuclear/cytoplasmic (N/C) ratio. Chromatin clearing, chromatin heterogeneity and hyperchromasia were seen in 102, 99 and 97 cases, respectively. All 28 cases involving non-neoplastic lesions revealed hyperplastic reactive pneumocytes, hyperplastic reactive bronchial epithelium, or degenerating macrophages. The non-neoplastic lesions revealed a small number of atypical cell clusters and paucity or absence of atypical single cells. Conclusion : The most important morphologic features for diagnosis of adenocarcinoma are nuclear membrane irregularities, non-cohesive cells, single atypical cell, moderate to markedly enlarged nuclei and increased N/C ratio. Chromatin clearing, chromatin heterogeneity and hyperchromasia were also helpful features, while pleomorphism and prominent nucleoli were less valuable.

• Genomics & Informatics
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• v.10 no.3
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• pp.145-152
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• 2012

Chromatin structure and dynamics that are influenced by epigenetic marks, such as histone modification and DNA methylation, play a crucial role in modulating gene transcription. To understand the relationship between histone modifications and regulatory elements in breast cancer cells, we compared our chromatin immunoprecipitation sequencing (ChIP-Seq) histone modification patterns for histone H3K4me1, H3K4me3, H3K9/16ac, and H3K27me3 in MCF-7 cells with publicly available formaldehyde-assisted isolation of regulatory elements (FAIRE)-chip signals in human chromosomes 8, 11, and 12, identified by a method called FAIRE. Active regulatory elements defined by FAIRE were highly associated with active histone modifications, like H3K4me3 and H3K9/16ac, especially near transcription start sites. The H3K9/16ac-enriched genes that overlapped with FAIRE signals (FAIRE-H3K9/14ac) were moderately correlated with gene expression levels. We also identified functional sequence motifs at H3K4me1-enriched FAIRE sites upstream of putative promoters, suggesting that regulatory elements could be associated with H3K4me1 to be regarded as distal regulatory elements. Our results might provide an insight into epigenetic regulatory mechanisms explaining the association of histone modifications with open chromatin structure in breast cancer cells.

• Journal of Life Science
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• v.21 no.4
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• pp.616-620
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• 2011

Lysine residues of histone H3 and H4 are covalently modified in the chromatin of eukaryotic cells. Lysine 27 in histone H3 was acetylated (H3K27ac) or methylated at three levels; mono-, di-, and trimethylation (H3K27me1, H3K27me2, and H3K27me3). These modifications at H3K27 were related with gene transcription and/or chromatin structure in distinct patterns. Generally, H3K27ac and H3K27me1 were enriched in active chromatin, such as the locus control region or transcriptionally active genes, while transcriptionally inactive genes were highly marked by H3K27me2 and H3K27me3. These modifications appear to have been catalyzed by distinct histone-modifying enzymes. Recent studies suggest that the four kinds of modifications at H3K27 have inter-correlation in gene transcription or chromatin structure formation.

• Clinical and Experimental Reproductive Medicine
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• v.47 no.1
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• pp.68-76
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• 2020

Objective: Since sperm abnormalities are known to be a major reason for recurrent pregnancy loss (RPL), any defects in DNA structure and chromatin condensation can place embryos at risk in the early stage of development and implantation. As antioxidants such as vitamin C may play a protective role against the destruction of protamine genes in sperm chromatin, this study was conducted to evaluate the effects of vitamin C on chromatin and the expression of protamine genes in the male partners of couples with RPL. Methods: Twenty male partners of couples with RPL were selected as the intervention group and received vitamin C supplementation (250 mg daily for 3 months). Healthy fertile men (n = 20) were included as controls. Sperm chromatin, DNA integrity, and the expression levels of protamine genes were evaluated before and after treatment. Results: Significant differences were found in sperm morphology, protamine deficiency, and apoptosis between the two groups and before and after vitamin C administration. A significant change was found in mRNA levels of PRM1, PRM2, and the PRM1/PRM2 ratio after treatment. Conclusion: Daily oral administration of vitamin C may improve human sperm parameters and DNA integrity by increasing protamine gene expression levels in the male partners of couples with RPL. The beneficial effects of vitamin C supplementation as an antioxidant for the male partners of couples with RPL could lead to improved pregnancy outcomes in these cases.