• 한국독성학회:학술대회논문집
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• 한국독성학회 2006년도 추계학술대회
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• pp.55-64
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• 2006

The fetal central nervous system (CNS) is sensitive to diverse environmental factors, such as alcohol, heavy metals, irradiation, mycotoxins, neurotransmitters, and DNA damage, because a large number of processes occur during an extended period of development. Fetal neural damage is an important issue affecting the completion of normal CNS development. As many concepts about the brain development have been recently revealed, it is necessary to compare the mechanism of developmental abnormalities induced by extrinsic factors with the normal brain development. To clarify the mechanism of fetal CNS damage, we used one experimental model in which 5-azacytidine (5AZC), a DNA damaging and demethylating agent, was injected to the dams of rodents to damage the fetal brain. 5AzC induced cell death (apoptosis)and cell cycle arrest in the fetal brain, and it lead to microencephaly in the neonatal brain. We investigated the mechanism of apoptosis and cell cycle arrest in the neural progenitor cells in detail, and demonstrated that various cell cycle regulators were changed in response to DNA damage. p53, the guardian of genome, played a main role in these processes. Further, using DNA microarray analysis, tile signal cascades of cell cycle regulation were clearly shown. Our results indicate that neural progenitor cells have the potential to repair the DNA damages via cell cyclearrest and to exclude highly affected cells through the apoptotic process. If the stimulus and subsequent DNA damage are high, brain development proceeds abnormally and results in malformation in the neonatal brain. Although the mechanisms of fetal brain injury and features of brain malformation afterbirth have been well studied, the process between those stages is largely unknown. We hypothesized that the fetal CNS has the ability to repair itself post-injuring, and investigated the repair process after 5AZC-induced damage. Wefound that the damages were repaired by 60 h after the treatment and developmental processes continued. During the repair process, amoeboid microglial cells infiltrated in the brain tissue, some of which ingested apoptotic cells. The expressions of genes categorized to glial cells, inflammation, extracellular matrix, glycolysis, and neurogenesis were upregulated in the DNA microarray analysis. We show here that the developing brain has a capacity to repair the damage induced by the extrinsic stresses, including changing the expression of numerous genes and the induction of microglia to aid the repair process.

• Journal of Nutrition and Health
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• 제32권5호
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• pp.526-532
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• 1999

The aim of this study was to observe whether the dietary supplementation of docosahexaenoic acid(DHA). In growing rats requires extra supplementation of arachidonic acid(AA) for brain development. Sprague-Dawley rats were divided into three groups, each fed a different diet. In the FO group, dams were fed a DHA-rich FO diet during pregnancy and lactation and pups were fed the same diet until 10 weeks old. In the AO group dams and pups were similarly fed a FO diet after weaning. DHA and AA were most effetively deposited in the developing brain during pregnancy and lactation in rats. However, FO-W pups showed significantly lower level of DHA at 0-3 weeks compared with the FO and AO groups and than slowly increased DHA levels to about 87% of other groups at 10 weeks with the introduction of the FO diet after weaning. The total amount of DNA in whole brain rapidly reached a maximum level at 3 weeks and then was sustained at a constant level after 5 weeks of age. The DNA content was positively correlated with DHA level but not with AA level in the developing brain. DNA content was significantly lower in the FO-W group compared to the FO and AO group at 3 weeks of age. However, the DNA content of brain in FO-W pups increased to 80% of the FO group level at 10 weeks after feeding the FO diet after weaning. The relative percentage of AA in brain lipids was significantly reduced in the early stage of brain development when only DHA was supplemented. However, DHA supplementation had no significant effect on the incorporation of AA when the approximately 35% of LA in the FO diet was substituted by preformed AA. These results suggest that large quantities of DHA could interfere with the normal conversion of LA to AA if LA is not supplemented enough together with DHA. Therefore, high DHA supplementation may require preformed AA in the diet even though AA has no significant correlation with the DNA content in brain. DHA supplementation after weaning also improved the incorporation of DHA into brain and content of DNA even though brain development was almost completed, suggesting that a low level of DHA supplementation without AA addition might be necessary to improve brain development during infancy as well as during pregnancy and lactation.

• Journal of Nutrition and Health
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• 제17권3호
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• pp.199-209
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• 1984

Pregnant rats were fed a pyridoxine deficient diet during the gestation and lactation. DEF I group received the deficient diet from delivery ; DEF II group, from the 15 th day of gestation. Body and brain weights, brain protein, DNA, RNA, plasma GOT and GPT, and catecholamines were measured. Effect of MAO inhibiting drug, pargyline, was determined. Brain protein, DNA, and RNA of offsprings of deficient groups were significantly lower than the control group, but RNA/ DNA, brain weight/DNA, and protein/DNA show that cell number were more affected than cell size by the pyridoxine deficiency during the 3rd week of gestation and lactation. Plasma GOT activities were more significantly different than plasma GPT between the control and deficient group. Brain norepinephrine of offsprings of deficient group were significantly lower than the control, but brain dopamine content was not significantly different from the control. At 2nd and 3rd week, norepinephrine was significantly depressed in deficient groups. Pargyline treatment affected a 1.2 fold increase in catecholamines in 3hr while the control had a 1.5 fold increase. Thus norepinephrine and dopamine synthesis was depressed in the deficient groups. Dopaminergic neurons may be less dependent on pyridoxine level than neurons from norepinephrine. Pyridoxine deficiency in maternal diet is not so critical to brain catecholamines of offspring except to the neonatal rats.

• BMB Reports
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• 제52권10호
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• pp.577-588
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• 2019

DNA methylation at CpG sites is an essential epigenetic mark that regulates gene expression during mammalian development and diseases. Methylome refers to the entire set of methylation modifications present in the whole genome. Over the last several years, an increasing number of reports on brain DNA methylome reported the association between aberrant methylation and the abnormalities in the expression of critical genes known to have critical roles during aging and neurodegenerative diseases. Consequently, the role of methylation in understanding neurodegenerative diseases has been under focus. This review outlines the current knowledge of the human brain DNA methylomes during aging and neurodegenerative diseases. We describe the differentially methylated genes from fetal stage to old age and their biological functions. Additionally, we summarize the key aspects and methylated genes identified from brain methylome studies on neurodegenerative diseases. The brain methylome studies could provide a basis for studying the functional aspects of neurodegenerative diseases.

• Animal cells and systems
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• 제5권3호
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• pp.231-236
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• 2001

SINE-R retroposons have been derived from human endogenous retrovirus HERV-K family and found to be hominoid specific. Both SINE-R retroposons and HERV-K family are potentially capable of affecting the expression of closely located genes. From cDNA library of human fetal brain, we identified seven SINE-R retroposons and compared them with sequences derived from GenBank database. The SINE-R retroposons from human feta1 brain showed 85∼97% sequence similarities with the human-specific retroposon SINE-R.C2. They also showed 88∼96% sequence similarities with the sequence of the schizo-cDNA clone that derived from postmortem frontal cortex tissue of a schizophrenic patient. Phylogenetic analysis using the neiqhbor-joining method revealed that the seven new SINE-R retroposons from cDNA library of the human feta1 brain have proliferated independently during human evolution. The data indicate that such SINE-R retroposons are expressed in human fetal brain and deserve further investigation as potential leads to understanding of neuropsychiatric diseases.

• 대한바이러스학회지
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• 제28권2호
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• pp.183-192
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• 1998

DNA methylation degree in the several murine brain and liver genes of different ages and after scrapie infection have been examined by using methylation-sensitive restriction endonuclease digestion. We found that the methylation of c-fos and c-myc in the brain and liver was increased during the late fetal to one month postnatal developmental periods. However, those of the SGP-2, $S100{\beta}$, APP950, PrP, and APLP1 genes were decreased at the same periods. The comparison of the DNA methylation patterns between scrapie infected brains and controls demonstrated there is no significant difference in methylation degree of scrapie-infected brains. These observations indicate that DNA methylation might be importantly related to the aging process. The scrapie-infected murine brain was not significantly developed more senescent than the same age-controls did.

• Journal of Nutrition and Health
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• 제40권1호
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• pp.14-23
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• 2007

Elevated plasma homocysteine (Hcy) is a risk factor for cognitive dysfunction and Alzheimer disease, although the mechanism is still unknown. Both folate and betaine, a choline metabolite, play essential roles in the remethylation of Hcy to methionine. Choline deficiency may be associated with low folate status and high plasma Hcy. Alterations in DNA methylation also have established critical roles for methylation in development of the nervous system. This study was undertaken to assess the effect of choline and folate deficiency on Hcy metabolism and genomic DNA methylation status of the liver and brain. Groups of adult male Sprague Dawley rats were fed on a control, choline-deficient (CD), folate-deficient (FD) or choline/folate-deficient (CFD) diets for 8 weeks. FD resulted in a significantly lower hepatic folate (23%) (p<0.001) and brain folate (69%) (p<0.05) compared to the control group. However, plasma and brain folate remained unaltered by CD and hepatic folate reduced to 85% of the control by CD (p<0.05). Plasma Hcy was significantly increased by FD $(18.34{\pm}1.62{\mu}M)$ and CFD $(19.35{\pm}3.62{\mu}M)$ compared to the control $(6.29{\pm}0.60{\mu}M)$ (p<0.001), but remained unaltered by CD. FD depressed S-adenosylmethionine (SAM) by 59% (p<0.001) and elevated S-adenosylhomocysteine (SAM) by 47% in liver compared to the control group (p<0.001). In contrast, brain SAM levels remained unaltered in CD, FD and CFD rats. Genomic DNA methylation status was reduced by FD in liver (p<0.05) Genomic DNA hypomethylation was also observed in brain by CD, FD and CFD although it was not significantly different from the control group. Genomic DNA methylation status was correlated with folate stores in liver (r=-0.397, p<0.05) and brain (r = -0.390, p<0.05), respectively. In conclusion, our data demonsoated that genomic DNA methylation and SAM level were reduced by folate deficiency in liver, but not in brain, and correlated with folate concentration in the tissue. The fact that folate deficiency had differential effects on SAM, SAH and genomic DNA methylation in liver and brain suggests that the Hcy metabolism and DNA methylation are regulated in tissue-specific ways.

• 대한의생명과학회지
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• 제4권2호
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• pp.137-142
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• 1998

쥐 뇌에서 발현되는 S-100 beta 유전자의 다형현상을 조사하였다. Polymerase chain reaction을 위한 주형으로는 뇌에서 분리한 mRNA를 직접 역전사한 cDNA, 또는 rat brain cDNA library에서 분리한 phage DNA를 사용하였다. 증폭된 DNA 절편들은 크기가 기존에 보고되었던 것과 일치하였으나 DNA sequencing을 통한 세부적인 분석 결과 coding region 내에 염기변화 (CAT가 CAC로 변함)가 있음이 확인되었다. 그러나 이들은 모두 histidine을 결정하는 유전암호이기에 단백질의 1차구조에는 아무런 영향을 미치지 않는 다형현상으로 결론지어졌다. 본 연구는 S-100 beta 단백질에 그동안 알려지지 않았던 다형현상이 존재함을 시사하는 것으로서 S-100beta 효소 유전자의 전체적인 구조를 이해하기 위한 학문적 자료가 될 것으로 기대된다.

• 한국독성학회:학술대회논문집
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• 한국독성학회 2000년도 국제심포지움 및 추계학술대회
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• pp.31-41
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• 2000

The major issue in the post genome sequencing era is determination of gene expression patterns in variety of biological systems. A microarray system is a powerful technology for analyzing the expression profile of thousands of genes at one experiment. In this study, we constructed cDNA microarray which carries 2,304 cDNAS derived from oligo-capped mouse cDNA library. Using this hand-made microarray we determined gene expression in various biological systems. To determine tissue specific genes, we compared Nine genes were highly-expressed in adult mouse brain compared to kidney, liver, and skeletal muscle. Tissue distribution analysis using DNA microarray extracted 9 genes that were predominantly expressed in the brain. A database search showed that five of the 9 genes, MBP, SC1, HiAT3, S100 protein-beta, and SNAP25, were previously known to be expressed at high level in the brain and in the nervous system. One gene was highly sequence similar to rat S-Rex-s/human NSP-C, suggesting that the gene is a mouse homologue. The remaining three genes did not match to known genes in the GenBank/EMBL database, indicating that these are novel genes highly-expressed in the brain. Our DNA microarray was also used to detect differentiation specific genes, hormone dependent genes, and transcription-factor-induced genes. We conclude that DNA microarray is an excellent tool for identifying differentially expressed genes.

• Journal of Nutrition and Health
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• 제14권2호
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• pp.105-116
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• 1981

분만전후 4주동안 Sqraque Dawley 암컷 쥐에게 양적으로 식이를 제한했다. 임의로 먹인 control group의 1일평균성취량의 1/2의 시중사로를 식이제한 group에게 주었다. Deficient I group에서는 분만후부터 이유시까지 식이제한을 했고, deficient II group에서는 임신 15일부터 이유시까지 계속 식이제한을 했다. 식이제한 group의 체중과 뇌무게는 control group의 새끼쥐보다 유의적으로 낮았지만, 체중에 대한 뇌무게의 비는 control group보다 높았다. 이유시에는 두 식이제한 group사이에서 체중과 뇌무게의 유의적인 차가 나타났다. 뇌의 DNA, RNA 및 단백질함량은 control group보다 식이제한 group에서 유의적으로 낮았지만 RNA/DNA, 뇌무게/DNA 및 단백질/DNA은 control group보다 식이제한 group에서 높았다. 이것은 새끼쥐뇌에서 세포분열이 세포의 크기성장보다 이 기간중의 어미쥐의 식이제한에 의해 더욱 심한 영향을 받았음을 시사해준다. 뇌의 DNA와 RNA는 두식이제한 group간에 유의적인 차를 나타내지만, 단백질의 경우는 유의적인 차를 나타내지 않았다.