• Korean Journal of Microbiology
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• v.53 no.4
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• pp.286-291
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• 2017

In eukaryotic cells, histone modification is an important mechanism to regulate the chromatin structure. The methylation of the fourth lysine on histone H3 (H3K4) by Set1 complex is one of the various well-known histone modifications. Set1 complex has seven subunits including Swd2, which is known to be important for H2B ubiquitination dependent on H3K4 methylation. Swd2 was reported to regulate Set1's methyltransferase activity by binding to near RNA recognition motif (RRM) domain of Set1 and to act as a component of CPF (Cleavage and Polyadenylation Factors) complex involved in RNA 3' end processing. According to the recent reports, two functions of Swd2 work independently of each other and the lethality of Swd2 knockout strain was known to be caused by its function as a component of CPF complex. In this study, we found that Swd2 could influence the Set1's stability as well as histone methyltransferase activity through the association with RRM domain of Set1. Also, we found that ${\Delta}swd2$ mutant bearing truncated-Set1, which cannot interact with Swd2, lost its lethality and grew normally. These results suggest that the dual functions of Swd2 in H3K4 methylation and RNA 3' end processing are not independent in Saccharomyces cerevisiae.

• 한국약용작물학회:학술대회논문집
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• 2008.11a
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• pp.467-468
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• 2008

• Korean Journal of Microbiology
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• v.54 no.1
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• pp.1-8
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• 2018

A prokaryotic cell has various histone-like proteins also known as nucleoid-associated proteins (NAPs). These proteins bind AT-rich sequence at DNA, which induce DNA wrapping, bending, and bridging, and subsequently regulate the gene expression in bacteria. Because NAPs function in transcriptional silencing of virulence genes, it is important to study their roles in gene silencing and specific mechanisms of these proteins. In this review, we discussed two well-known NAPs, H-NS, and HU, and summarized their roles for gene expression in Escherichia coli and Salmonella Typhimurium. Through the oligomerization and filamentation of H-NS, it represses the expression of virulence genes in human pathogenic bacteria, such as Salmonella Typhimurium, and it works with other NAPs positively or negatively. Recently, H-NS also regulates typhoid toxin expression, which causes typhoid fever and systemic disease in human. Additionally, HU regulates the expression of genes related to both virulence and physiology of Salmonella. Therefore, we suggest that NAPs like H-NS and HU are crucial factors to reveal the molecular mechanisms of virulence gene expression in bacteria.

• Radiation Oncology Journal
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• v.22 no.2
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• pp.138-141
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• 2004

Purpose : We have previously reported that human glioblastoma cells are sensitized to radiation-induced death after their exposure to trichostatin A (TSA), a histone deacetylase inhibitor (HDAC-1), prior to the irradiation. We aimed to measure the magnitude of the radiosensitizing effect of TSA in human head and neck cancer cell lines. Materials and Methods : Human head and neck cancer cell lines, HN-3 and HN-9, were exposed to 0, 50, 100, and 200 nM TSA for 18 hr prior to irradiation. Then, the TSA-treated cells were irradiated with 0, 2, 4, 6, and 8 Gy, and cell survival was measured by clonogenic assay. Results : Pre-irradiation exposure to TSA was found to radiosensitize HN-3 and HN-9 cell lines. In HN-9 cells, the fraction surviving after 2 Gy (SF2) was significantly reduced by treatment of TSA at concentration as low as 50 nM. However, a treatment with 200 nM TSA was required to significantly decrease SF2 in the HN-3 cell line. SER of pre-irradiation treatment with 200 nM TSA was 1.84 in HN-3 and 7.24 in HN-9, respectively. Conclusions : Our results clearly showed that human head and neck cancer cell lines can be sensitized to ionizing radiation by pre-irradiation inhibition of histone deacetylase (HDAC) using TSA, and that this potentiation might well be a general phenomenon.

• Radiation Oncology Journal
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• v.28 no.4
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• pp.219-223
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• 2010

Purpose: To test the radiosensitizing effect of the newly synthesized novel histone deacetylase inhibitor, SK-7041 in vivo. Materials and Method: The RIF-l cell line was implanted into the back of a 6-week-old female C3H mouse, intradermally, The mice were grouped into control, drug, radiation (RT), and RT+drug group. SK-7041, 4 mg/kg was administered intraperitoneally for six cycles every 12 hours for mice in the drug and RT+drug group, An identical volume of phosphate buffered saline (PBS) was administered at the same frequency to mice in the control and RT groups. A single 5 Gy fraction was delivered to mice in RT and RT+drug group 6 hours after the fourth delivery. The volume of the implanted tumor was measured every 2~3 days to formulate the growth delay curve. Results: For the control, drug, RT, and RT +drug groups, the average duration for implanted tumor to reach a volume of $1,500mm^3$ was 10 days, 10 days, 9 days, and 12 days, respectively. Moreover, the tumor volume on D14 was $276.7mm^3$, $279.9mm^3$, $292.5mm^3$, and $185.5mm^3$, respectively (p=0.0004). The difference for the change in slope for the control and drug versus the RT and RT+drug groups were borderline significant (p=0.0650). Conclusion: The results of this study indicate that SK-7041 has a radiosensitizing effect for the RIF-1 cell line in vivo at a low concentration and this effect may be synergistic. Implementing this result to clinical trial is warranted.

• Radiation Oncology Journal
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• v.23 no.2
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• pp.116-122
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• 2005

Purpose: Histone deacetylase inhibitors (HDIs) are emerging as potentially useful components of anticancer therapy and their radiosensitizing effects have become evident. Specific HDAS are now available that preferentially inhibit specific HDAC classes; TSA inhibits Class I and II HDACs, and SK7041 inhibits Class I HDACs. Materials and methods: We tested the differential radiosensitization induced by two different classes of HDIs in HeLa cells. We next tested the hypothesis that p53 expression in cancer cells may influence the susceptibility to HDIs by using pharmacologic modification of the p53 status under an isogenic background. Results: It is interesting that p53 expression in the HeLa cells clearly increased the degree of radio-sensitization by TSA compared to that of the class I specific inhibitor SK7041. This suggests that p53 may, in part, be responsible for the mechanistic role for the greater radiosensitization induced by Class I & II inhibitors compared to that of the class I specific inhibitors. Thus, these studies are useful in distinguishing between events mediated solely by the Class I HDACS versus those events involving the other classes of HDACS as well. Conclusion: The anticancer efficacy of targeting Class I and II HDACS, in conjunction with radiation therapy, may be further enhanced by the restoration of p53 expression.

• Proceedings of the Korea Contents Association Conference
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• 2013.05a
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• pp.75-76
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• 2013

유전자 염기서열의 직접적인 변화 대신 후성기작을 통해 유전자 발현이 조절되는 후성유전은 크게 DNA 메틸화(methylation), 히스톤 변형(modification), ncRNA(non-coding RNA)로 제어가 가능하다. 후성유전을 이해하기 위해 노화 관련 유전자를 대상으로 데이터베이스를 구축하고 전반적인 연구결과를 살펴보고자 한다. 유전자의 프로모터(promoter), CpG island(CGI) 부위에 메틸화가 될 경우 다른 부위에 비해 유전자 발현에 큰 영향을 주므로, 특히 CGI 부위를 중심으로 전체 유전자 그룹과 노화 관련 유전자 그룹간의 분포도를 비교 분석하였다. 또한 ncRNA 중 miRNA와 노화 유전자와의 상호작용을 분석하였다. 이와 같은 분석접근 방법은 노화 관련 유전자의 조절을 이해하는데 도움이 될 것으로 사료된다.

• Journal of Life Science
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• v.17 no.4 s.84
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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.

• Proceedings of the Korea Contents Association Conference
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• 2012.05a
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• pp.355-356
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• 2012

후성유전은 DNA 염기 서열이 변화하지 않고 DNA의 메틸화(methyaltion) 및 히스톤 단백질의 변형(modification)등의 후천적 과정에 의해 유전자 발현이 조절되는 현상이다. 특히 DNA 메틸화 정도에 대한 패턴 분석은 후성유전을 이해하는 중요한 접근방법중 하나이다. DNA 메틸화 패턴 분석을 위해 발생에 관련된 123개 유전자들의 -5000bp ~ +200bp사이에 있는 DNA 염기 서열 정보를 추출하였다. 추출한 염기 서열 정보를 기반으로 기존에 알려진 메틸화 경향성 모티프와 메틸화 저항성 모티프를 모니터링 함으로써 발생관련 유전자들의 메틸화 모티프 패턴을 분석하였다. 결과적으로 메틸화 저항 모티프만이 발견되었고 따라서 메틸화 저항 모티프 패턴과 발생관련 유전자들의 상관관계를 분석하였다.

• Proceedings of the Korea Contents Association Conference
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• 2012.05a
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• pp.357-358
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• 2012

후성유전은 DNA 염기서열이 변화하지 않은 상태에서 특별한 후성적 조절 기전에 의해 유전자의 발현 양상이 변하는 현상이다. 후성적 조절 기전에는 DNA의 메틸화(methyaltion)와 히스톤 단백질의 변형(modification), non coding RNA에 의한 조절 등이 포함되는데, 이 중 DNA 메틸화 정도에 대한 패턴 분석은 후성유전을 이해하는 중요한 접근방법 중 하나이다. 네트워크와 DNA 메틸화 분석을 위하여 면역관련 264개 유전자들의 -2000bp ~ +200bp사이에 있는 DNA 염기 서열 정보를 추출하였다. 또한 면역관련 단백질들의 상호작용 정보를 이용하여 네트워크를 구축하고 여기에 메틸화 정보를 적용하여 상호작용과 메틸화 모티프와의 관계를 분석하였다. 메틸화 모티프 정보를 적용한 단백질 네트워크에서는 기존 단백질 네트워크보다 더 복잡한 구조를 이루고 있었다. 이러한 구조는 동일한 메틸화 모티프들이 여러 유전자들의 활성을 조절할 것으로 사료된다. 단백질 상호작용 네트워크에 모티프를 적용한 분석은 새로운 후성유전학적 연구를 위한 접근 방법으로 이용될 수 있을 것이다.