• Journal of Microbiology and Biotechnology
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• 제11권5호
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• pp.819-824
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• 2001

The principal DNA modification systems of the amino-acid-producing bacteria Corynebacterium glutamicum AS019, Brevibacterium flavum BF4, and B. lactofermentum BL1 was investigated using two approaches; digestion of plasmid DNA isolated from these species TseI and Fnu4HI, and sequence analysis of the putative methyltransferase target sites following the derivatization of DNA using metabisulfite treatment. The C. glutamicum and B. flavum strains showed similar digestion patterns to the two enzymes, indicating that the target for cytidine methyltransferase recognizes 5'-GCSGC-3'(where S is either G or C). Mapping the methylated cytidine sites by bisulfite derivatization, followed by PCR amplification and sequencing, was only possible when the protocol included an additional step eliminating any underivatized DNA after PCR amplification, thereby indicating that the derivatization was not $100\%$ efficient. This may have been due to the high G0C content of this genus. It was confirmed that C. glutamicum AS019 and B. flavum BF4 methylated the cytidine in the $Gm^5CCGC$ sequences, yet there were no similar patterns of methylation in B. lactofermentum, which was consistent with the distinctive degradation pattern seen for the above enzymes. These findings demonstrate the successful application of a modified bisulfite derivatization method with the Corynebacterium species for determining methylation patterns, and showed that different species in the geneus contain distinctive restriction and modification systems.

• Asian-Australasian Journal of Animal Sciences
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• 제18권11호
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• pp.1655-1661
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• 2005

The present studies were designed to provide new information on fatty acid profiles of various muscles and adipose tissues of fattening horses in comparison with beef cattle and pigs. In the first study, the lipids were extracted respectively from subcutaneous, intermuscular adipose tissues, longissimus dorsi and biceps femoris muscles of fattening Breton horses (n = 8) with an average body weight of 1,124 kg. In the second study, the lipids were extracted from subcutaneous, intermuscular adipose tissues and longissimus dorsi muscle of fattening horses (n = 13), Japanese Black beef cattle (n = 5), Holstein steers (n = 5) and fattening pigs (n = 5). The fatty acids in the lipid samples were determined by gas chromatography after methylation by a combined base/acid methylation method. It was found that the lipids from horse subcutaneous and intermuscular adipose tissues contained more (p<0.05) polyunsaturated fatty acids (PUFA) which were mainly composed of linoleic acid (C18:2) and linolenic acid (C18:3) than those in the muscles. The weight percent of conjugated linoleic acids (CLA cis 9, trans 11) in lipids from biceps femoris muscle was 0.22%, which was higher (p<0.05) than that from the other depots. The horse lipids were higher (p<0.05) in PUFA but lower (p<0.05) in SFA and MUFA in comparison with those of the cattle and pigs. The percentage of C18:2 or C18:3 fatty acid in the horse lipids were respectively 2-8 fold or 5-18 fold higher (p<0.05) than those of the cattle and pigs. The percentages of CLA (cis 9, trans 11) in the horse lipids (0.14-0.16%) were very close to those of the pigs (0.18-0.19%) but much lower (p<0.05) than those of the Japanese Black beef cattle (0.55-0.94%) and Holstein steers (0.46-0.71%). The results indicated that the fatty acid profiles of lipids from different muscle and adipose tissues of fattening horses differed significantly. In comparison with that of the beef cattle and pigs, the horse lipids contained more C18:2 and C18:3 but less CLA.

• Bulletin of the Korean Chemical Society
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• 제12권4호
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• pp.392-397
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• 1991

A stereocontrolled synthesis of (${\pm}$)-isocomene (1) via selective monoketalization of tricyclo[6.3.0.$0^{1.5}$]undeca-4,7-dione(13) was reported. Grignard reaction of bicyclic enone 10, which was prepared from 2-methyl-1,3-cyclopentadione, gave the 1,4-addition product 11. The subsequent aldol condensation product 12 was converted to mesyl derivative 13. Transformation from 13 to the desired product 19 was achieved by a series of reactions, i.e., the selective monoketalization at C-4 carbonyl group, the elimination of a mesyl group, Birch alkylation, methylation at C-6, the reduction of carbonyl group, the dehydration of alcohol 18, and hydrolysis of the ketal group.

• 대한의생명과학회지
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• 제11권2호
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• pp.165-173
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• 2005

A potent demethylating agent, 5-Azacytidine (5-AzaC) has been widely used as in many studies on DNA methylation, regulation of gene expression, and cancer biology. The mechanisms of the demethylating activity were known to be formation of complex between DNA and DNA methyltransferase (MTase), which depletes cellular MTase activity. However, 5-AzaC can also induce hypermethylation of a transgene in a transgenic cell line, G12 cells and it was explained as a result of defense mechanisms to inactivate foreign gene(s) somehow. This finding evoked the question that whether the phenomenon of hypermethylation induced by 5-AzaC is limited to the transgene or it can be occurred in endogenous gene(s). In order to answer the question, mutagenicity test of 5-AzaC and molecular characterization of mutants obtained from the test were performed using an endogenous gene, thymidine kinase (tk) in Chinese hamster V79 cells. When V79 and V79-J3 subclone cells were treated with 1, 2.5 ,5, $10{\mu}M$ of 5-AzaC for 48 hours, their maximum mutant frequencies were revealed as $6\times10^{-3}\;at\;5{\mu}M$(350-fold induction over background) and $8\times10^{-3}\;at\;2.5{\mu}M$ (l,800-fold induction over background) respectively. Since the induction rates were too high to be induced by true mutations, many trifluorothymidine (TFT)-resistant $(TFT^R)$ cells were subjected to Northern blot analysis to check the presence of tk transcripts. Surprisingly, all clones tested possessed the transcripts in a similar level, that implicates the $TFT^R$ phenotype induced by 5-AzaC has not given rise to hypermethylation of the gene in spite of unusually high mutation frequency. In addition, it has shown that the TK activity in the pool of 5-AzaC-induced $TFT^R$ cells has about a half of that in spontaneously-induced $TFT^R$ cells or in non-selected parental V79-J3 cells. This result suggests that the mechanism(s) underlying the TFT-resistance between spontaneously occurred and 5-AzaC-induced cells may be different. These findings have shown that the $TFT^R$ phenotype induced by 5-AzaC has not given rise to hypermethylation of the tk gene, and 5-AzaC may be induced by one or combined pathways among many drug resistance mechanisms. The exact mechanisms for the 5-AzaC-induced $TFT^R$ phenotype remain to elucidate.

• Asian Pacific Journal of Cancer Prevention
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• 제16권12호
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• pp.5007-5011
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• 2015

Background: Breast cancer is a major cause of morbidity and mortality in Jordan and worldwide. Abnormality of DNA methylation is a possible mechanism for the development of cancer. Methylenetetrahydrofolate reductase (MTHFR) is involved in DNA methylation. Our aim was to study the association between genetic polymorphisms of MTHFR at two sites (C677T and A1298C) and their haplotypes and the risk of breast cancer among Jordanian females. Materials and Methods: A case-control study involving 150 breast cancer cases and 150 controls was conducted. Controls were age-matched to cases. Polymerase chain reaction/restriction fragment length polymorphism (PCR-RFLP) technique and sequencing were conducted to determine the genotypes. Results: There was a significant difference in genotype frequency of C677T in the 41-60 year age category [cases: CC (37.4%), CT (49.5%) and TT (13.2%); controls: CC (56.3%), CT (35.6%) and TT (8%), p= 0.04; $OR_{TT\;vs.\;CC}$: 2.5, 95% CI: (0.9-6.9); $OR_{at\;least\;on\;T$: 2.1, 95%CI: (1.2-3.9)]. There was no significant difference in genotype frequency of A1298C between cases and controls [cases: AA (46.6%), AC (41.8%) and CC (11.6%); controls: AA (43%), AC (47.4%) and CC (9.6%); p= 0.6]. There was a significant difference of MTHFR genetic polymorphism haplotypes among breast cancer cases and controls [cases/control: CA: 38.3/45.4%; CC: 28.9/25.2%; TA: 29.2/21; TC: 3.6/8.3; p value= 0.01; $OR_{TA\;vs.\;CA}=1.6$; 95% CI (1.1-2.5); p= 0.02]. Conclusions: Genetic polymorphism of MTHFR C677T may modulate the risk of breast cancer especially in the 41-60 year age group. Additionally, TA haplotype amends the risk of breast cancer. Future studies with a larger sample size are needed to validate the role of MTHFR genetic polymorphisms in breast cancer.

• 한국자원식물학회지
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• 제7권1호
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• pp.89-95
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• 1994

Antileukemic tropoloisoquinoline alkaloids, pareirubine A (1) and gandirubrine (2), at first have been isolated from.Abuta concolor (Menisper-maceae). Methylation of 1 and 2, existing in solution as a mixture of tautomersgave the corresponding four methyl derivatives (3 -6). Thioimerubrine (7) andthioisoimerubrine (8) were prepared by the nucleophilic substitutions of themethoxyl groups at C-11 and -10, respectively. Acetylation of 1 and 2produced the corresponding mono-acetyl tautomers (9 and 10). Antileukemicactivity of these derived tropoloisoquinoline alkaloids is also reported.

• Molecules and Cells
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• 제38권11호
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• pp.925-935
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• 2015

DNA methylation is a well-characterized epigenetic modification that plays central roles in mammalian development, genomic imprinting, X-chromosome inactivation and silencing of retrotransposon elements. Aberrant DNA methylation pattern is a characteristic feature of cancers and associated with abnormal expression of oncogenes, tumor suppressor genes or repair genes. Ten-eleven-translocation (TET) proteins are recently characterized dioxygenases that catalyze progressive oxidation of 5-methylcytosine to produce 5-hydroxymethylcytosine and further oxidized derivatives. These oxidized methylcytosines not only potentiate DNA demethylation but also behave as independent epigenetic modifications per se. The expression or activity of TET proteins and DNA hydroxymethylation are highly dysregulated in a wide range of cancers including hematologic and non-hematologic malignancies, and accumulating evidence points TET proteins as a novel tumor suppressor in cancers. Here we review DNA demethylation-dependent and -independent functions of TET proteins. We also describe diverse TET loss-of-function mutations that are recurrently found in myeloid and lymphoid malignancies and their potential roles in hematopoietic transformation. We discuss consequences of the deficiency of individual Tet genes and potential compensation between different Tet members in mice. Possible mechanisms underlying facilitated oncogenic transformation of TET-deficient hematopoietic cells are also described. Lastly, we address non-mutational mechanisms that lead to suppression or inactivation of TET proteins in cancers. Strategies to restore normal 5mC oxidation status in cancers by targeting TET proteins may provide new avenues to expedite the development of promising anti-cancer agents.

• Asian Pacific Journal of Cancer Prevention
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• 제16권18호
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• pp.8093-8100
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• 2016

Background: Genetic and environmental factors play important roles in pathogenesis of digestive tract cancers like those in the esophagus, stomach and colorectum. Folate deficiency and methylenetetrahydrofolate reductase (MTHFR) as an important enzyme of folate and methionine metabolism are considered crucial for DNA synthesis and methylation. MTHFR variants may cause genomic hypomethylation, which may lead to the development of cancer, and MTHFR gene polymorphisms (especially C677T and A1298C) are known to influence predispositions for cancer development. Several case control association studies of MTHFR C677T polymorphisms and colorectal cancer (CRC) have been reported in different populations with contrasting results, possibly reflecting inadequate statistical power. Aim: The present meta-analysis was conducted to investigate the association between the C677T polymorphism and the risk of colorectal cancer. Materials and Methods: A literature search of the PubMed, Google Scholar, Springer link and Elsevier databases was carried out for potential relevant articles. Pooled odds ratio (OR) with corresponding 95 % confidence interval (95 % CI) was calculated to assess the association of MTHFR C677T with the susceptibility to CRC. Cochran's Q statistic and the inconsistency index (I2) were used to check study heterogeneity. Egger's test and funnel plots were applied to assess publication bias. All statistical analyses were conducted by with MetaAnalyst and MIX version 1.7. Results: Thirty four case-control studies involving a total of 9,143 cases and 11,357 controls were retrieved according to the inclusion criteria. Overall, no significant association was found between the MTHFR C677T polymorphism and colorectal cancer in Asian populations (for T vs. C: OR=1.03; 95% CI= 0.92-1.5; p= 0.64; for TT vs CC: OR=0.88; 95%CI= 0.74-1.04; p= 0.04; for CT vs. CC: OR = 1.02; 95%CI= 0.93-1.12; p=0.59; for TT+ CT vs. CC: OR=1.07; 95%CI= 0.94-1.22; p=0.87). Conclusions: Evidence from the current meta-analysis indicated that the C677T polymorphism is not associated with CRC risk in Asian populations. Further investigations are needed to offer better insight into any role of this polymorphism in colorectal carcinogenesis.

• Journal of Chest Surgery
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• 제42권2호
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• pp.141-147
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• 2009

배경: 폐암의 암화과정에 관여하는 21번 염색체 장완에 존재하는 종양억제유전자를 발굴하고자 하였다. 대상 및 방법: 21q11.2 구역의 USP25, 21q21.2 구역의 NCAM2, ADAMTS1, 그리고 21q22.1 구역의 Claudin-8 (CLDN8), Claudin-17 (CLDN17), TIAM1 유전자를 대상으로 비소세포폐암 세포주에서 이들 유전자의 발현 정도와 돌연변이 및 촉진자 메틸화 유무를 조사하였다. 결과: 13가지 비소세포폐암 세포주 가운데 7가지 세포주(L132, H157, H358, H522, H1299, H1703, HCC2108)에서 CLDN8, CLDN17의 발현이 유의하게 감소되었고, ADAMTS1의 경우 6가지 세포주(A549, SW900, H1299, H1373, H1703, H1793)에서 발현양이 유의하게 감소되었다. 유전자 발현의 감소가 있는 세포주와 그렇지 않은 세포주간의 PCR-SSCP의 band pattern의 차이가 없으며 염기서열의 분석에서도 genetic alteration은 관찰되지 않았다. 발현이 감소되어 있는 세포주에 5-Aza-CdR을 처리한 경우 유전자의 발현양이 유의하게 증가되었다. 결론: ADMTS1, CLDN8, CLDN17 유전자는 폐암의 암화과정에 관여하는 종양억제유전자일 가능성을 시사하며, 유전자의 발현 감소는 유전자 촉진자 부위의 methylation에 의함을 시사한다.

• Journal of Microbiology and Biotechnology
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• 제7권4호
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• pp.272-277
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• 1997

In the purification of elaiophylin from a culture of Streptomyces hygroscopicus MCY -846, mono- and di-methyl-elaiophylin were obtained through a O-methylation of the hemiketal hydroxy group of elaiophylin. All the three elaiophylins showed cytotoxicity against several human tumor cell lines and murine cell lines. Elaiophylin and monomethyl-elaiophylin also showed antimicrobial activities against gram-positive bacteria and potent inhibitory effects on the activation of B cells by lipopolysaccharide as well as on the proliferation of mouse splenic lymphocytes stimulated by mitogens but dimethyl-elaiophylin did not. This result indicates that elaiophylin and monomethyl-elaiophylin would be strong immunosuppressants. Furthermore this result revealed an interesting structure-activity relationship suggesting that the lack of symmetry and/or the free OH group at C-11 of elaiophylin might be important in conferring biological activities.