• 생명과학회지
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• 제17권4호
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• pp.593-598
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• 2007

Amino acids of histone tail are covalently modified in eukaryotic cells. Lysine residues in histone H3 and H4 are methylated at three levels; mono-, di- or trimethylation. Methylation in histones is related with transcription of the genes in distinct pattern depending on lysine residues and methylated levels. Relation between transcription and methylation has been relatively well understood at three lysines H3K4, H3K9 and H3K36. H3K4 is methylated in active or potentially active chromatin and its methylation associates with active transcription. H3K9 is generally methylated in heterochromatin or repressed gene, but trimethylation of this lysine occur in actively transcribed genes also. Methylation at H3K36 generally correlates with active chromatin/transcription, but the correlation of its dimethylation with transcription is controversial. All together methylation patterns of individual lysine residues in histone relate with activation or repression of transcription and may provide distinctive roles in transcriptional regulation of the eukaryotic genes.

• Journal of Microbiology and Biotechnology
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• 제27권1호
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• pp.189-196
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• 2017

Kaposi's sarcoma-associated herpesvirus (KSHV) is associated with formation of Kaposi's sarcoma, multicentric Castleman's disease, and primary effusion lymphoma. Replication and transcription activator (RTA) genes are expressed upon reactivation of KSHV, which displays a biphasic life cycle consisting of latent and lytic replication phases. RTA protein expression results in KSHV genome amplification and successive viral lytic gene expression. Transcriptional activity of viral lytic genes is regulated through epigenetic modifications. In Raji cells latently infected with Epstein-Barr virus, various modifications, such as acetylation and methylation, have been identified at specific lysine residues in histone H4 during viral reactivation, supporting the theory that expression of specific lytic genes is controlled by histone modification processes. Data obtained from chromatin immunoprecipitation and quantitative real-time PCR analyses revealed alterations in the H4K8ac and H4K20me3 levels at lytic gene promoters during reactivation. Our results indicate that H4K20me3 is associated with the maintenance of latency, while H4K8ac contributes to KSHV reactivation in infected TREx BCBL-1 RTA cells.

• Genomics & Informatics
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• 제8권4호
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• pp.201-205
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• 2010

The H1 histone family, member N, testis-specific (H1FNT) is exclusively expressed in the testis, and had its possible role for sperm chromatin formation. The purpose of this study is to investigate any genetic association of H1FNT gene with male infertility, especially at the promoter region. We examined the promoter single nucleotide polymorphisms (SNP) of H1FNT gene which is located within transcription factor binding site for its association with male infertility. The statistical analysis showed that the -1129A>T polymorphism was present at a statistically significance in male infertility (p=0.0059 and 0.0349 for hetero and risk type, respectively). The dual-luciferase promoter assay was performed to examine the polymorphic effect of this promoter SNP by the cloning of promoter region (1700bp fragment) into pGL3-basic vector. In our plasmid based reporter system, there is no big difference between wild and risk type. In conclusion, H1FNT -1129A>T promoter SNP is statistically significant with male infertility, especially with subfertile (non-azoospermia) group. Further analysis of its functional polymorphic effect in vivo may provide the biological significance of testis-specific histone with spermatogenesis.

• 생명과학회지
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• 제31권11호
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• pp.995-1003
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• 2021

크로마틴 리모델링은 후성유전기전을 통해 유전자 발현을 조절한다. 비정상적인 히스톤 변형이 우울증 발생에 관여하는 것으로 알려져 있다. p11 (S100A10)은 인간과 설치류에서 우울증의 병태생리에 관여한다고 보고되었다. 본 연구는 우울증 동물모델인 장기간 예측 불가능한 스트레스가 마우스 해마에서 p11 유전자 promoter의 히스톤 변형에 미치는 영향을 조사하고자 하였다. C57BL/6 마우스에 21일 동안 스트레스를 가하고, 강제수영검사를 수행하여 우울 유사 행동 양상을 측정하였다. Real time PCR 및 Western blotting 분석법으로 p11 발현 변화를 조사하였으며, 염색질 면역침전분석법을 수행하여 p11 promoter의 히스톤 H3 아세틸화 및 메틸화 양을 측정하였다. 장기간 예측 불가능한 스트레스는 강제수영검사에서 부동시간을 증가시켜 우울 유사 행동을 나타내었으며, 해마의 p11 mRNA 및 단백질 발현을 유의하게 감소시켰다. 또한 p11 promoter의 히스톤 H3 아세틸화(Ac-H3) 및 H3-K4 트리메틸화(H3K4met3)를 유의하게 감소시켰으며, H3-K27 트리메틸화(H3K27met3)를 증가시켰다. 본 연구결과는 만성 스트레스가 해마에서 p11 유전자의 후성유전적 억제를 야기하여 p11 유전자의 발현을 감소시킴을 시사한다.

• Genes and Genomics
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• 제40권12호
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• pp.1301-1308
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• 2018

Background Adipocyte differentiation is completed by changing gene expression. Chromatin is closely related to gene expression. Therefore, its structure might be changed for adipocyte differentiation. Mouse 3T3-L1 preadipocytes have been used as a cell model to study molecular mechanisms of adipogenesis. Objective To examine changes of chromatin modification and expression of histone modifying enzymes during adipocyte differentiation. Methods Microscopic analysis and Oil Red O staining were performed to determine distinct phenotype of adipocyte differentiation. RT-PCR and Western blot analysis were used to examine expression levels of histone modifying enzymes during adipocyte differentiation. Histone modifications were examined by immunostaining analysis. Results Expression levels of P300 and cbp were increased during adipocyte differentiation. However, acetylation of histones was not quantitatively changed postdifferentiation of 3T3-L1 cells compared to that at pre-differentiation. RT-PCR and Western blot analyses showed that expression levels of hdac2 and hdac3 were increased during adipocyte differentiation, suggesting histone acetylation at chromatin level was homeostatically controlled by increased expression of both HATs and HDACs. Tri-methylation level of H3K9 (H3K9me3), but not that of H3K27me3, was significantly decreased during adipocyte differentiation. Decreased expression of setdb1 was consistent with reduced pattern of H3K9me3. Knock-down of setdb1 induced adipocyte differentiation. This suggests that setdb1 is a key chromatin modifier that modulates repressive chromatin. Conclusion These results suggest that there exist extensive mechanisms of chromatin modifications for homeostatic balance of chromatin acetylation and deconstruction of repressive chromatin during adipocyte differentiation.

• Journal of Microbiology and Biotechnology
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• 제28권9호
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• pp.1573-1579
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• 2018

Transcriptional gene silencing is regulated by the chromatin structure, which is by various factors including histones. Saccharomyces cerevisiae contains transcriptionally silenced regions such as telomeric regions and hidden mating (HM) loci. The positively-charged amino acids on the histone H4 tail were reported to be critical for the telomeric silencing in yeast, by interacting with Dot1, a specific methyltransferase for the $79^{th}$ lysine on histone H3. However, Dot1 did not affect gene silencing within HM loci, but whether the positively-charged amino acids on the H4 tail affect HM silencing has not been defined. To elucidate the function of the H4 tail on HM silencing, we created several MATa-type yeast strains bearing the substitution of arginine with alanine or lysine on the histone H4 tail and checked the sensitivity of MATa-type yeast to alpha pheromone. The arginine point mutants substituted by alanine (R17A, R19A, and R23A) did not show sensitivity to alpha pheromone, but only two arginine mutants substituted by lysine (R17K and R19K) restored the sensitivity to alpha pheromone-like wild type. These data suggested that the basic property of arginine at $17^{th}$ and $19^{th}$ positions in the histone H4 tail is critical for maintaining HM silencing, but that of the $23^{rd}$ arginine is not. Our data implicated that the positive charge of two arginine residues on the histone H4 tail is required for HM silencing in a manner independent of Dot1.

• The Plant Pathology Journal
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• 제36권4호
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• pp.314-322
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• 2020

Interplay between histone acetylation and deacetylation is one of the key components in epigenetic regulation of transcription. Here we report the requirement of MoHDA1-mediated histone deacetylation during asexual development and pathogenesis for the rice blast fungus, Magnaporthe oryzae. Structural similarity and phylogenetic analysis suggested that MoHDA1 is an ortholog of Saccharomyces cerevisiae Hda1, which is a representative member of class II histone deacetylases. Targeted deletion of MoHDA1 caused a little decrease in radial growth and large reduction in asexual sporulation. Comparison of acetylation levels for H3K9 and H3K14 showed that lack of MoHDA1 gene led to significant increase in H3K9 and H3K14 acetylation level, compared to the wild-type and complementation strain, confirming that it is a bona fide histone deacetylase. Expression analysis on some of the key genes involved in asexual reproduction under sporulation-promoting condition showed almost no differences among strains, except for MoCON6 gene, which was up-regulated more than 6-fold in the mutant than wild-type. Although the deletion mutant displayed little defects in germination and subsequent appressorium formation, the mutant was compromised in its ability to cause disease. Wound-inoculation showed that the mutant is impaired in invasive growth as well. We found that the mutant was defective in appressorium-mediated penetration of host, but did not lose the ability to grow on the media containing H₂O₂. Taken together, our data suggest that MoHDA1-dependent histone deacetylation is important for efficient asexual development and infection of host plants in M. oryzae.

• BMB Reports
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• 제48권12호
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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.

• Molecules and Cells
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• 제37권10호
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• pp.734-741
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• 2014

Histone modifications on major transcription factor target genes are one of the major regulatory mechanisms controlling adipogenesis. Plant homeodomain finger 2 (PHF2) is a Jumonji domain-containing protein and is known to demethylate the histone H3K9, a repressive gene marker. To better understand the function of PHF2 in adipocyte differentiation, we constructed stable PHF2 knock-down cells by using the mouse pre-adipocyte cell line 3T3-L1. When induced with adipogenic media, PHF2 knock-down cells showed reduced lipid accumulation compared to control cells. Differential expression using a cDNA microarray revealed significant reduction of metabolic pathway genes in the PHF2 knock-down cell line after differentiation. The reduced expression of major transcription factors and adipokines was confirmed with reverse transcription- quantitative polymerase chain reaction and Western blotting. We further performed co-immunoprecipitation analysis of PHF2 with four major adipogenic transcription factors, and we found that CCATT/enhancer binding protein (C/EBP)${\alpha}$ and C/EBP${\delta}$ physically interact with PHF2. In addition, PHF2 binding to target gene promoters was confirmed with a chromatin immunoprecipitation experiment. Finally, histone H3K9 methylation markers on the PHF2-binding sequences were increased in PHF2 knock-down cells after differentiation. Together, these results demonstrate that PHF2 histone demethylase controls adipogenic gene expression during differentiation.

• 한국발생생물학회지:발생과생식
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• 제15권4호
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• pp.273-279
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• 2011

후성유전학적 조절은 DNA 서열상의 변화 없이도 유전자의 기능을 변화시킬 수 있는 현상을 뜻한다. 염색체의 후성유전학적 상태는 히스톤 변형, DNA 변형 그리고 RNAi에 의한 유전자 침묵 등에 의해 조절된다. 본 총설에서는 배아줄기세포에서의 후성 유전학적 조절에 영향을 주는 요인으로서 히스톤(histone)의 메틸화에 초점을 맞추었다. 배아줄기세포에서 발현되는 유전자의 조절에는 두 가지 단백질 복합체가 관여한다. Polycomb repressive complex 2(PRC2)는 EED, EZH2, SUZ1를 주요인자로 포함하며, H3K27의 trimethylation(H3K27me3)을 증가시킴으로써 유전자의 발현을 억제한다. 이와는 대조적으로 Trithorax group(TrxG) 복합체는 주요인자로 MLL family를 포함하며, H3K4의 trimethylation(H3K4me3) 시킴으로써 유전자의 발현을 활성화한다. PRC2 및 TrxG는 다양한 보조 단백질을 포함한다. 배아줄기세포에서 후성유전학적 조절의 두드러진 특징은 H3K27me3과 H3K4me3이 동시에 나타나는 이가 상태(bivalent state)이다. PRC2와 TrxG 복합체 그리고 H3K4나 K3K27의 메틸화에 특이적으로 작용하는 탈메틸효소(demethylase)가 한데 어우러져 배아줄기세포에서 만능성 관련 유전자와 발달 관련 유전자의 발현을 조절함으로써 줄기세포의 유지 및 분화에 기여한다. 따라서 후성유전학적 조절인자들에 대한 보다 자세한 연구는 배아줄기세포를 보다 잘 이해하고 활용하는데 도움을 줄 것이다.