• Biomedical Science Letters
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• v.18 no.2
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• pp.165-168
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• 2012

Hox proteins containing DNA-binding homedomain act as transcription factors important for anteroposterior body patterning during vertebrate embryogenesis. However, the precise mechanisms by which signal pathways are transduced to regulate the Hox gene expression are not clear. In the course of an attempt to isolate an upstream regulatory factor(s) controlling Hox genes, protein kinase B alpha (Akt1) has been identified as a putative regulator of Hox genes through in silico analysis (GEO profile). In the Gene Expression Omnibus (GEO) dataset GDS1784 at the NCBI (National Center for Biotechnology Information) site, Hox genes were differentially expressed depending on the presence or absence of Akt1. Since it was not well known how Akt1 regulates the specific Hox genes, whose transcription was reported to be regulated by epigenetic modifications such as histone acetylation, methylation etc., the expression of Gcn5, a histone acetyltransferase (HAT), was analyzed in wild type (WT) as well as in $Akt1^{-/-}$ mouse embryonic fibroblast (MEF) cells. RT-PCR analysis revealed that the amount of Gcn5 mRNA was similar in both WT and $Akt1^{-/-}$ MEFs. However, the protein level of Gcn5 was significantly increased in $Akt1^{-/-}$ MEF cells. The half life of Gcn5 was 1 hour in wild type whereas 8 hours in $Akt1^{-/-}$ MEF. These data all together, indicate that Gcn5 is post-transcriptionally down-regulated and the protein stability is negatively regulated by Akt1 in MEF cells.

• Korean Journal of Clinical Oncology
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• v.9 no.2
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• pp.80-86
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• 2013

Purpose: Hypermethylation of human mut L homologue 1 (hMLH1) promoter region is known to cause sporadic microsatellite instability (MSI) colorectal cancers. 5,10-methylenetetrahydrofolate reductase (MTHFR) is the key enzyme in folate metabolism, acting as a methyl donor for DNA methylation. In this study, we investigate whether the polymorphism of MTHFR 677C>T plays a role in the alteration of the promoter-specific hypermethylation, predisposing to MSI colorectal cancers. Methods: Total of 487 sporadic colorectal cancer patients in CHA Bundang Medical Center were collected. MSI was identified when two or more are positive among five microsatellite markers (BAT25, BAT26, D17S250, D5S346, D2S123). The others were classified as microsatellite stable (MSS). Polymorphism of MTHFR 677C>T was genotyped by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Results: MSI was observed in 65 of 487 patients (12.73%). MSI colorectal cancers showed similar clinicopathological features with previously reported; younger age onset, right-sided preponderance, mucinous and poorly differentiated histology, lower stage, fewer lymph node metastases than MSS tumors (each P<0.05). The frequency of MTHFR 677TT genotype was 17.7% in the MSI group higher than 14.6% in the MSS group (P=0.17). Although not statistically significant, compared to the MTHFR 677CC referent, MTHFR 677 CT+TT genotype was more likely to have MSI than MSS (odds ratio, 1.81; 95% confidence interval, 0.94 to 3.68; P=0.06). Conclusion: This study demonstrated higher frequency of MTHFR 677TT genotype in MSI colorectal cancers. Furthermore, individuals with MTHFR 677CT+TT variant type might potentially develop MSI rather than MSS colorectal cancers.

• Clinical and Experimental Pediatrics
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• v.45 no.9
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• pp.1126-1133
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• 2002

Purpose : Prader-Willi syndrome(PWS) is a complex disorder affecting multisystems with characteristic clinical features. Its genetic basis is an expression defect in the paternally derived chromosome 15q11-q13. We analyzed the clinical features and genetic basis of PWS patients for early detection and treatment. Methods : We retrospectively studied 24 patients with PWS in Department of Pediatrics, Samsung Medical Center, from September 1997 to September 2001. We performed cytogenetic and molecular genetic techniques using high resolution GTG banding techniques, fluorescent in situ hybridization and methylation-specific PCR for CpG island of SNRPN gene region. Results : The average birth weight of PWS patients was $2.67{\pm}0.47kg$ and median age at diagnosis was 1.3 years. The average height and weight of PWS patients under one year at diagnostic time were located in a 3-10 percentile relatively, and a rapid weight gain was seen between two and six years. Feeding problems in infancy and neonatal hypotonia were the two most consistently positive major criteria in over 95% of the patients. In 18 of the 24 cases(75%), deletion of chromosome 15q11-q13 was demonstrated and one case among 18 had an unbalanced 14;15 translocation. In four cases without any cytogenetic abnormality, it may be considered as maternal uniparental disomy and the rest showed another findings. Conclusion : We suggest diagnostic testing for PWS in all infants/neonates with unexplained feeding problems and hypotonia. It is necessary for clinically suspicious patients to undergo an early genetic test. As the genetic basis of PWS was heterogenous and complex, further study is required.

• Molecules and Cells
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• v.37 no.2
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• pp.178-186
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• 2014

Differential transcription of the clusterin (CLU) gene yields two CLU isoforms, a nuclear form (nCLU) and a secretory form (sCLU), which play crucial roles in prostate tumorigenesis. Pro-apoptotic nCLU and anti-apoptotic sCLU have opposite effects and are differentially expressed in normal and cancer cells; however, their regulatory mechanisms at the transcriptional level are not yet known. Here, we examined the transcriptional regulation of nCLU in response to hypoxia. We identified three putative hypoxia response elements (HREs) in the human CLU promoter between positions -806 and +51 bp. Using a luciferase reporter, electrophoretic gel mobility shift, and chromatin immunoprecipitation assays, we further showed that hypoxia-inducible factor-$1{\alpha}$ (HIF-$1{\alpha}$) bound directly to these sites and activated transcription. Exposure to the hypoxia-mimetic compound $CoCl_2$, incubation under 1% $O_2$ conditions, or overexpression of HIF-$1{\alpha}$ enhanced nCLU expression and induced apoptosis in human prostate cancer PC3M cells. However, LNCaP prostate cancer cells were resistant to hypoxia-induced cell death. Methylation-specific PCR analysis revealed that the CLU promoter in PC3M cells was not methylated; in contrast, the CLU promoter in LNCap cells was methylated. Co-treatment of LNCaP cells with $CoCl_2$ and a demethylating agent promoted apoptotic cell death through the induction of nCLU. We conclude that nCLU expression is regulated by direct binding of HIF-$1{\alpha}$ to HRE sites and is epigenetically controlled by methylation of its promoter region.

• The Journal of the Korean bone and joint tumor society
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• v.15 no.1
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• pp.13-25
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• 2009

Purpose: The DNA repair protein, $O^6$-methylguanine-DNA methyltransferase (MGMT), removes alkyl adducts from the $O^6$ position of guanine. Epigenetic inactivation of MGMT has been found in human neoplasia and considered one of the implicated factors in chemoresistance. Materials and Methods: Sixty-two patiensts with soft tissue sarcomas (STS) were analyzed for the status of MGMT protein expression by immunohistochemistry and the promoter hypermethylation of the MGMT gene using methylation-specific PCR. Result: The loss of MGMT expression was found in 20 cases (32.3%) of total 62 STS. MGMT promoter hypermethylation rate was 25.0% (11/44 cases). The loss of MGMT expression showed significant association with high AJCC stage, high FNCLCC grade, and aggressive behavior. However,when the group who received chemotherapy was analyzed (n=27), loss of MGMT expression was correlated with worse survival in multivariate analysis (p=0.024). MGMT promoter hypermethylation is associated with high FNCLCC grade. MGMT promoter hypermethylation status had a strong correlation with loss of MGMT expression (p=0.000). Conclusion: Our results suggest that MGMT promoter hypermethylation and loss of MGMT expression had a tendency to be associated with poor prognosis and that loss of MGMT protein expression is frequently occurs via MGMT promoter hypermethylation.

• Journal of Life Science
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• v.25 no.11
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• pp.1214-1222
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• 2015

The purpose of this study was to determine the effect of Pueraria lobate-root based combination supplementation containing Rehmannia glutinosa and exercise on histone modification in ovariectomized rat hindlimb skeletal muscle. Sixty rats were fed with high fat diet and randomly assigned into the following groups for 8 weeks: 1)HSV; High fat+Sedentary+Vehicle, 2)HSP; High fat+Sedentary+PR, 3)HSH; High fat+Sedentary+Estradiol, 4)HEV; High fat+Ex+Vehicle, 5)HEP; High fat+Ex+PR, 6)HEH; High fat+Ex+Estradiol. Exercise consisted of low intensity treadmill exercise(1-4th wk:15 m/min for 30 min, 5-8th wk: 18 m/min for 40 min, 5 times/week). The result of this study showed that exercise and Pueraria and Rehmannia glutinosa intake suppressed weight gain. Furthermore, exercise and Pueraria and Rehmannia glutinosa intake increased muscle mass. This study observed H3K9 acetylation and demethylation in plantaris muscle in exercised group, but no difference in soleus muscle. To test whether the decrease in HDAC4, HDAC5 and G9a mRNA levels after exercise and Pueraria/Rehmannia glutinosa intake, HDAC4, HDAC5 and G9a mRNA levels were determined by real-time PCR. Only exercise induced HDAC5 and G9a mRNA reduction in plantaris muscle, but not in soleus muscle. In conclusion, these data demonstrates that exercise and Pueraria/Rehmannia glutinosa intake effect on body compositions. These changes are regulated by epigenetic modifications, such as histone acetylation and methylation. Future studies should focus on gene-specific epigenetics and other epigenetic mechanism for Pueraria/Rehmannia glutinosa intake.