• Reproductive and Developmental Biology
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• 제31권4호
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• pp.241-248
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• 2007

Epigenetic modification dependent DNA methyltransferases (DNMTs) play an important role in tissue- and stage-specific gene regulation and normal mammalian development. In this study, we show that DNMTs are expressed at different levels during hematopoietic stem cell (HSC) differentiation to proerythrocytes. DNMT1, DNMT3A, and DNMT3B were highly expressed at day 7 after differentiation. We used specific siRNA as a tool to probe the relationship between the expression of DNMTs and erythropoietic differentiation. When introduced siRNA of DMNT1 and DMNT3b in human $CD34^+$ cells, these more differentiated into erythrocytes. This was confirmed by glycophorin A (GPA) positive cell analysis and globin gene expression. $GPA^+$ cells increased up to $20{\sim}30%$, and ${\gamma}$- and ${\epsilon}$-globin genes increased in siRNA transfected cells. Therefore, our data suggest that suppression of DNA methylation can affect positively differentiation of HSC and may contribute to expression of erythrocyte lineage genes including GPA and globins.

• Genomics & Informatics
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• 제11권1호
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• pp.34-37
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• 2013

This study evaluated the effects of somatic mutations and single nucleotide polymorphisms (SNPs) on disease progression and tried to verify the two-hit theory in cancer pathogenesis. To address this issue, SNP analysis was performed using the UCSC hg19 program in 10 acute myeloid leukemia patients (samples, G1 to G10), and somatic mutations were identified in the same tumor sample using SomaticSniper and VarScan2. SNPs in KRAS were detected in 4 out of 10 different individuals, and those of DNMT3A were detected in 5 of the same patient cohort. In 2 patients, both KRAS and DNMT3A were detected simultaneously. A somatic mutation in IDH2 was detected in these 2 patients. One of the patients had an additional mutation in FLT3, while the other patient had an NPM1 mutation. The patient with an FLT3 mutation relapsed shortly after attaining remission, while the other patient with the NPM1 mutation did not suffer a relapse. Our results indicate that SNPs with additional somatic mutations affect the prognosis of AML.

• BMB Reports
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• 제54권8호
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• pp.413-418
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• 2021

ErbB3-binding protein 1 (EBP1) is a multifunctional protein associated with neural development. Loss of Ebp1 leads to upregulation of the gene silencing unit suppressor of variegation 3-9 homolog 1 (Suv39H1)/DNA (cytosine 5)-methyltransferase (DNMT1). EBP1 directly binds to the promoter region of DNMT1, repressing DNA methylation, and hence, promoting neural development. In the current study, we showed that EBP1 suppresses histone methyltransferase activity of Suv39H1 by promoting ubiquitin-proteasome system (UPS)-dependent degradation of Suv39H1. In addition, we showed that EBP1 directly interacts with Suv39H1, and this interaction is required for recruiting the E3 ligase MDM2 for Suv39H1 degradation. Thus, our findings suggest that EBP1 regulates UPS-dependent degradation of Suv39H1 to govern proper heterochromatin assembly during neural development.

• Molecules and Cells
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• 제42권1호
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• pp.67-78
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• 2019

Methylation of HBV cccDNA has been detected in vivo and in vitro; however, the mechanism and its effects on HBV replication remain unclear. HBx derived from a 1.2-mer HBV replicon upregulated protein levels and enzyme activities of DNA methyltransferase 1 (DNMT1), 3a, and 3b, resulting in methylation of the negative regulatory region (NRE) in cccDNA, while none of these effects were observed with an HBx-null mutant. The HBx-positive HBV cccDNA expressed higher levels of HBc and produced about 4-fold higher levels of HBV particles than those from the HBx-null counterpart. For these effects, HBx interrupted the action of NRE binding protein via methylation of the C-1619 within NRE, resulting in activation of the core promoter. Treatment with 5-Aza-2′dC or DNMT1 knock-down drastically impaired the ability of HBx to activate the core promoter and stimulate HBV replication in 1.2-mer HBV replicon and in vitro infection systems, indicating the positive role of HBx-mediated cccDNA methylation in HBV replication.

• Journal of Gastric Cancer
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• 제14권3호
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• pp.147-155
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• 2014

Homeostatic imbalance between cell proliferation and death in gastric mucosal epithelia may lead to gastritis and gastric cancer. Despite abundant gastrokine 1 (GKN1) expression in the normal stomach, the loss of GKN1 expression is frequently detected in gastric mucosa infected with Helicobacter pylori, as well as in intestinal metaplasia and gastric cancer tissues, suggesting that GKN1 plays an important role in gastric mucosal defense, and the gene functions as a gastric tumor suppressor. In the stomach, GKN1 is involved in gastric mucosal inflammation by regulating cytokine production, the nuclear factor-${\kappa}B$ signaling pathway, and cyclooxygenase-2 expression. GKN1 also inhibits the carcinogenic potential of H. pylori protein CagA by binding to it, and up-regulates antioxidant enzymes. In addition, GKN1 reduces cell viability, proliferation, and colony formation by inhibiting cell cycle progression and epigenetic modification by down-regulating the expression levels of DNMT1 and EZH2, and DNMT1 activity, and inducing apoptosis through the death receptor-dependent pathway. Furthermore, GKN1 also inhibits gastric cancer cell invasion and metastasis via coordinated regulation of epithelial mesenchymal transition-related protein expression, reactive oxygen species production, and PI3K/Akt signaling pathway activation. Although the modes of action of GKN1 have not been clearly described, recent limited evidence suggests that GKN1 acts as a gastricspecific tumor suppressor. This review aims to discuss, comment, and summarize the recent progress in the understanding of the role of GKN1 in gastric cancer development and progression.

• 한국발생생물학회지:발생과생식
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• 제25권4호
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• pp.213-223
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• 2021

Controlled ovarian hyperstimulation (COH) is routinely used in the in vitro fertilization and embryo transfer (IVF-ET) cycles to increase the number of retrieved mature oocytes. However, the relationship between repeated COH and ovarian function is still controversial. Therefore, we investigated whether repeated ovarian stimulation affects ovarian aging and function, including follicular development, autophagy, and apoptosis in follicles. Ovarian hyperstimulation in mice was induced by intraperitoneal injection with pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG). Mice subjected to ovarian stimulation once were used as a control group and 10 times as an experimental group. Repeated injections with PMSG and hCG significantly reduced the number of primary follicles compared to a single injection. The number of secondary and antral follicles increased slightly, while the number of corpus luteum increased significantly with repeated injections. On the other hand, repeated injections did not affect apoptosis in follicles associated with follicular atresia. The expression of autophagy-related genes Atg5, Atg12, LC3B, and Beclin1, cell proliferation-related genes mTOR, apoptosis-related genes Fas, and FasL was not significantly different between the two groups. In addition, the expression of the aging-related genes Dnmt1, Dnmt3a, and AMH were also not significantly different. In this study, we demonstrated that repeated ovarian stimulation in mice affects follicular development, but not autophagy, apoptosis, aging in ovary. These results suggest that repetition of COH in the IVF-ET cycle may not result in ovarian aging, such as a decrease in ovarian reserve in adult women.

• Journal of Ginseng Research
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• 제47권4호
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• pp.515-523
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• 2023

Background: 20(S)-protopanaxadiol (PPD), one of the main components of ginseng, has anti-inflammatory, anti-estrogenic, and anti-tumor activities. It is known that activated hepatic stellate cells (HSCs) are the primary producers of extracellular matrix (ECM) in the liver, and the Wnt/β-catenin pathway participates in the activation of HSCs. We aimed to explore whether PPD inhibits liver fibrosis is associated with the Wnt/β-catenin pathway inactivation. Methods: The anti-fibrotic roles of PPD were examined both in vitro and in vivo. We also examined the levels of Wnt inhibitory factor 1 (WIF1), DNA methyltransferase 1 (DNMT1) and WIF1 methylation. Results: PPD obviously ameliorated liver fibrosis in carbon tetrachloride (CCl₄)-treated mice and reduced collagen deposition. PPD also suppressed the activation and proliferation of primary HSCs. Notably, PPD inhibited the Wnt/β-catenin pathway, reduced TCF activity, and increased P-β-catenin and GSK-3β levels. Interestingly, WIF1 was found to mediate the inactivation of the Wnt/β-catenin pathway in PPD-treated HSCs. WIF1 silencing suppressed the inhibitory effects of PPD on HSC activation and also restored α-SMA and type I collagen levels. The downregulation of WIF1 expression was associated with the methylation of its promoter. PPD induced WIF1 demethylation and restored WIF1 expression. Further experiments confirmed that DNMT1 overexpression blocked the effects of PPD on WIF1 expression and demethylation and enhanced HSC activation. Conclusion: PPD up-regulates WIF1 levels and impairs Wnt/β-catenin pathway activation via the downregulation of DNMT1-mediated WIF1 methylation, leading to HSC inactivation. Therefore, PPD may be a promising therapeutic drug for patients with liver fibrosis.

• Journal of Periodontal and Implant Science
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• 제47권2호
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• pp.66-76
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• 2017

Purpose: Oral wound healing requires gingival fibroblasts to respond to local growth factors. Epigenetic silencing through DNA methylation can potentially decrease the responsiveness of gingival fibroblasts to local growth factors. In this study, our aim was to determine whether the inhibition of DNA methylation sensitized gingival fibroblasts to transforming growth factor-${\beta}1$ (TGF-${\beta}1$). Methods: Gingival fibroblasts were exposed to 5-aza-2'-deoxycytidine (5-aza), a clinically approved demethylating agent, before stimulation with TGF-${\beta}1$. Gene expression changes were evaluated using quantitative polymerase chain reaction (PCR) analysis. DNA methylation was detected by methylation-sensitive restriction enzymes and PCR amplification. Results: We found that 5-aza enhanced TGF-${\beta}1$-induced interleukin-11 (IL11) expression in gingival fibroblasts 2.37-fold (P=0.008). 5-aza had no significant effects on the expression of proteoglycan 4 (PRG4) and NADPH oxidase 4 (NOX4). Consistent with this, 5-aza caused demethylation of the IL11 gene commonly next to a guanosine (CpG) island in gingival fibroblasts. The TGF-${\beta}$ type I receptor kinase inhibitor SB431542 impeded the changes in IL11 expression, indicating that the effects of 5-aza require TGF-${\beta}$ signaling. 5-aza moderately increased the expression of TGF-${\beta}$ type II receptor (1.40-fold; P=0.009), possibly enhancing the responsiveness of fibroblasts to TGF-${\beta}1$. As part of the feedback response, 5-aza increased the expression of the DNA methyltransferases 1 (DNMT1) (P=0.005) and DNMT3B (P=0.002), which are enzymes responsible for gene methylation. Conclusions: These in vitro data suggest that the inhibition of DNA methylation by 5-aza supports TGF-${\beta}$-induced IL11 expression in gingival fibroblasts.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제30권3호
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• pp.302-309
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• 2008

DNA 메틸화는 histone modification과 함께 DNA의 염기서열이 유지되면서 유전기능이 변화되고 자손까지 전달 될 수 있는 후생 유전의 중요한 한 부분이다. DNA 메틸화는 크로마틴의 구조를 변경시키는 과정을 통하여 유전자와 repetitive sequence의 표현을 억제시킬 수 있다. DNA 메틸화는 X-불활성화, 유전체 각인, 유전자 발현조절, 암 생성 등에 중요한 역할을 하는 것으로 밝혀졌고, DNA 메틸화 표지자 (DNA methylation marker)들은 종양의 진단과 치료에 대한 반응을 예측하는 지표로 활용되고 있다. 지금까지 많은 연구 성과에도 불구하고 DNA메틸화, 메틸화에 의한 gene silencing, DNA 메틸화의 표적부위 등에 대한 명확한 기전이 아직도 밝혀지지 않고 있어 향후 더 많은 기초적 연구가 필요할 것이다. 최근에는 후생 유전적 변화는 가역적이기 때문에 종양억제유전자를 억압하는 후생 유전적 변화를 제거한다면 그 종양억제유전자를 다시 활성화시킬 수 있다는 개념의 후생유전 치료법 연구로 DNA 메틸화 억제제와 histone deacetyaltion에 관여하는 HDAC의 억제제들이 항암제로서 개발되어 사용되고 있는데 향후 더 많은 약제 개발과 임상적 연구가 진행되어야 할 것이다.

• 한국동물번식학회:학술대회논문집
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• 한국동물번식학회 2003년도 학술발표대회 발표논문초록집
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• pp.27-27
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• 2003

A diversified and concentrative approach of methylation player can be one of the most powerful studies in the understanding of global epigenetic modifications. Previous studies have suggested that DNA methylation contributes to transcriptional silencing through the several DNA methylation-mediated repression systems by hypermethylation, including methyltransferases (DNMTs), DNA methyltransferase association protein 1 (DMAPl), methyl-CpG binding domain (MBD), and histone deacetylases (HDACs). Assembly of these regulatory protein complexes act sequentially, reciprocally, and interdependently on the newly composed DNA strand through S phase. Therefore, these protein complexes have a role in coupling DNA replication to the designed turn-off system in genome. In this study, we attempted to address the role of DNA methylation by the functional analysis of the methyltransferase molecule, we described the involvement of DMAP1 and DNMTs in cell divistion and the effect of their loss. We also described distinct patterns that DMAP1 and DNMTs are spatially reorganized and displaced from condensing chromosomes as cells progress through mitosis in HeLa cell, COS7, and HIH3T3 cell cycle progressions. DNMT1, DNMT3b, and DMAP1 do not stably contact the genetic material during chromosome compaction and repressive expression. These finding show that the loss of activities of DNMTs and DMAP1 occure stage specifically during the cell cycle, may contribute to the integral balance of global DNA methylation. This is consistent with previous studies resulted in decreased histone acetyltransferases and HDACs, and differs from studies resulted in increased histone methyltransferases. Our results suggest that DNA methylation by DNMTs and DMAP1 during mitosis acts to antagonize hypermethylation by which this mark is epigenetical mitotic-specific methylation.