유전자 구조와 기능

沈龍姬 대한의사협회 1998 대한의사협회지 Vol.41 No.9

간암조직에서 DNA methyltransferase의 발현

이귀연,박혜정,심용희 建國大學校基礎科學硏究所 2002 理學論集 Vol.27 No.-

암억제유전자의 과메틸화는 유전자의 발현을 억제하는 작용으로 암발생 기전에 중요한 요인으로 알려져 왔다. DNA 과메틸화는 DNA methyltransferase (Dnmt)에 의해서 생성되는데 현재까지 그 기능이 알려진 것으로 Dnmt1, Dnmt3a, Dnmt3b가 있다. 본 논문에서는 한국인의 간암조직 27개과 각 예에 상응되는 정상조직 27 개에서 위의 세 효소의 발현정도를 역전사효소-중합연쇄반응으로 조사하였다. Dnmt1는 정상조직에서 40.7% (11/27), 간암조직에서 33.3% (9/27); Dnmt3a는 정상조직에서 22.2% (6/27), 간암조직에서 63% (17/27); Dnmt3b는 정상조직에서는 전혀 발현 되지 않았으며 간암조직에서 51.9% (14/27)가 발현되었다. Dnmt1은 유전자의 메틸화정도를 유지시키는 기능을 하는 반면에 Dnmt3a와 Dnmt3b는 de novo 메틸화를 담당한다. Dnmt3a와 Dnmt3b의 발현이 Dnmt1보다 1.6-1.9 배 간암조직에서 높았으며 정상조직에서는 Dnmt1 (40.7%)의 발현이 22.2%인 Dnmt3a와 전혀 발현을 보이지 않은 Dnmt3b보다 훨씬 높았다. 위의 실험결과는 정상조직에서는 유전자의 메틸화를 유지하기 위하여 DNA 메틸화가 되는 반면에 종양조직에서는 새로운 유전자의 메틸화가 유발됨을 시사한다. 이는 새로운 유전자의 과메틸화의 증가가 암 발생기전의 요인이 될 가능성을 제시하는 결과이다. Hypermethylation on CpG islands of a tumor suppressor gene has been frequently detected in a variety of cancer cells and known to repress the level of transcription. To identify the molecular mechanism for hypermethylation of tumor suppressor genes in hepatocellular carcinomas (HCC), we examined DNA methyltransferase (Dnmt) expression level in HCC. Three Dnmts, Dnmt1, Dnmt3a and Dnmt3b that have been identified as being enzymatically active were examined by RT-PCR. Expression of Dnmts was detected in both non-neoplastic control liver and in HCC. Eleven out of 27 (40.7%) controls and 9 out of 27 (33.3%) HCC; 6 out of 27 (22.2%) controls and 17 out of 27 (63%) HCC; none of 27 controls and 14 out of 27 (51.9%) HCC revealed expression of Dnmt1, Dnmt3a, and Dnmt3b, respectively. The relatively high frequency of Dnmt1 expression in non-neoplastic control suggests that expression of Dnmt1 is required for maintenance of methylation profile in non-neoplastic cells. In addition, higher frequencies of Dnmt3a and Dnmt3b expression in HCC suggest that de novo DNA methylation in tumor cells may be the major process for gene inactivation during hepatocarcinogenesis.

Hypermethylation of Multiple Tumor Suppressor Genes in the Different Histologic Types of Meningiomas

Hee Sun Kim,Jeong Hoon Kim,Yhong Hee Shim 한국유전학회 2005 Genes & Genomics Vol.27 No.4

Caffeine Induces the Stress Response and Up-Regulates Heat Shock Proteins in Caenorhabditis elegans

YHONG-HEE SHIM,Mohammad Al-Amin,Ichiro Kawasaki,Joomi Gong 한국분자세포생물학회 2016 Molecules and cells Vol.39 No.2

Caffeine has both positive and negative effects on physiological functions in a dose-dependent manner. C. elegans has been used as an animal model to investigate the effects of caffeine on development. Caffeine treatment at a high dose (30 mM) showed detrimental effects and caused early larval arrest. We performed a comparative proteomic analysis to investigate the mode of action of high-dose caffeine treatment in C. elegans and found that the stress response proteins, heat shock protein (HSP)-4 (endoplasmic reticulum [ER] chaperone), HSP-6 (mitochondrial chaperone), and HSP-16 (cytosolic chaperone), were induced and their expression was regulated at the transcriptional level. These findings suggest that high-dose caffeine intake causes a strong stress response and activates all three stress-response pathways in the worms, including the ER-, mitochondrial-, and cytosolic pathways. RNA in-terference of each hsp gene or in triple combination re-tarded growth. In addition, caffeine treatment stimulated a food-avoidance behavior (aversion phenotype), which was enhanced by RNAi depletion of the hsp-4 gene. Therefore, up-regulation of hsp genes after caffeine treatment appeared to be the major responses to alleviate stress and protect against developmental arrest.

LIN-23, an E3 Ubiquitin Ligase Component, Is Required for the Repression of CDC-25.2 Activity during Intestinal Development in Caenorhabditis elegans

YHONG-HEE SHIM,Miseol Son,Ichiro Kawasaki,Bong-Kyeong Oh 한국분자세포생물학회 2016 Molecules and cells Vol.39 No.11

Caenorhabditis elegans (C. elegans) utilizes two different cell-cycle modes, binucleations during the L1 larval stage and endoreduplications at four larval moltings, for its postembryonic intestinal development. Previous genetic studies indicated that CDC-25.2 is specifically required for binucleations at the L1 larval stage and is repressed before endoreduplications. Furthermore, LIN-23, the C. elegans -TrCP ortholog, appears to function as a re-pressor of CDC-25.2 to prevent excess intestinal divi-sions. We previously reported that intestinal hyperplasia in lin-23(e1883) mutants was effectively suppressed by the RNAi depletion of cdc-25.2. Nevertheless, LIN-23 tar-geting CDC-25.2 for ubiquitination as a component of E3 ubiquitin ligase has not yet been tested. In this study, LIN-23 is shown to be the major E3 ubiquitin ligase com-ponent, recognizing CDC-25.2 to repress their activities for proper transition of cell-cycle modes during the C. elegans postembryonic intestinal development. In addi-tion, for the first time that LIN-23 physically interacts with both CDC-25.1 and CDC-25.2 and facilitates ubiquitination for timely regulation of their activities during the intestinal development.

Methylation of CpG Islands in the Rat 7-dehydrocholesterol Reductase Promoter Suppresses Transcriptional Activation

Yhong-Hee Shim,Jai-Hyun Kim,Eun-Ha Hwang,Hye-Jung Park,Young-Ki Paik 한국분자세포생물학회 2005 Molecules and cells Vol.19 No.2

In mammals, 7-dehydrocholesterol reductase (Dhcr7) is the terminal enzyme in cholesterol biosynthesis. We previously reported that the Dhcr7 proximal promoter (−179 to +1), which contains CpG islands, is responsible for sterol-mediated expression of the rat gene. Inthe present study, we examined whether methylation of this region affects the transcriptional activity of the Dhcr7 gene. In vitro DNA methylation of the Dhcr7 promoter and luciferase-reporter assays showed that DNA methylation of the CpG islands suppressed transcription. Furthermore, treatment of the methylated Dhcr7 promoter with the demethylating agent, 5-aza-2′-deoxycytidine (5-Aza-CdR), reversed the suppression of promoter activity. These results indicate that methylation of the CpG islands is an important transcriptional regulatory mechanism in the Dhcr7 promoter.

elt-1, a Gene Encoding a Caenorhabditis elegans GATA Transcription Factor, Is Highly Expressed in the Germ Lines with msp Genes As the Potential Targets

Shim, Yhong-Hee Korean Society of Molecular Biology 1999 Molecules and cells Vol.9 No.5

Caenorhabditis elegans proteomics comes of age

Shim, Yhong-Hee,Paik, Young-Ki WILEY-VCH Verlag 2010 Proteomics Vol.10 No.4

<P>Caenorhabditis elegans, a free-living soil nematode, is an ideal model system for studying various physiological problems relevant to human diseases. Despite its short history, C. elegans proteomics is receiving great attention in multiple research areas, including the genome annotation, major signaling pathways (e.g. TGF-β and insulin/IGF-1 signaling), verification of RNA interference-mediated gene targeting, aging, disease models, as well as peptidomic analysis of neuropeptides involved in behavior and locomotion. For example, a proteome-wide profiling of developmental and aging processes not only provides basic information necessary for constructing a molecular network, but also identifies important target proteins for chemical modulation. Although C. elegans has a simple body system and neural circuitry, it exhibits very complicated functions ranging from feeding to locomotion. Investigation of these functions through proteomic analysis of various C. elegans neuropeptides, some of which are not found in the predicted genome sequence, would open a new field of peptidomics. Given the importance of nematode infection in plants and mammalian pathogenesis pathways, proteomics could be applied to investigate the molecular mechanisms underlying plant– or animal–nematode pathogenesis and to identify novel antinematodal drugs. Thus, C. elegans proteomics, in combination of other molecular, biological and genetic techniques, would provide a versatile new tool box for the systematic analysis of gene functions throughout the entire life cycle of this nematode.</P>

Effects of Ginsenosides, Active Ingredients of <i>Panax ginseng</i>, on Development, Growth, and Life Span of <i>Caenorhabditis elegans</i>

Lee, Joon-Hee,Choi, Sun-Hye,Kwon, Oh-Seung,Shin, Tae-Joon,Lee, Jun-Ho,Lee, Byung-Hwan,Yoon, In-Soo,Pyo, Mi Kyung,Rhim, Hyewhon,Lim, Yoong-Ho,Shim, Yhong-Hee,Ahn, Ji-yun,Kim, Hyoung-Choon,Chitwood, Dav Pharmaceutical Society of Japan 2007 BIOLOGICAL & PHARMACEUTICAL BULLETIN Vol.30 No.11

<P>The backbone structure of ginsenosides, active ingredients of <I>Panax ginseng</I>, is similar with that of sterol, especially cholesterol. <I>Caenorhabditis elegans</I> (<I>C. elegans</I>) is one of free living nematodes and is well-established animal model for biochemical and genetic studies. <I>C. elegans</I> cannot synthesize <I>de novo</I> cholesterol, although cholesterol is essential requirement for its growth and development. In the present study, we investigated the effects of ginseng total saponins (GTS) on the average brood size, growth, development, worm size, and life span of <I>C. elegans</I> in cholesterol-deprived and -fed medium. Cholesterol deprivation caused damages on normal growth, reproduction, and life span of worms throughout F1 to F3 generations. GTS supplement to cholesterol-deprived medium restored the growth, reproduction, and life span of worms as much as cholesterol alone-fed medium. GTS co-supplement to cholesterol-fed medium not only promoted worm reproduction but also induced bigger worms and faster growth than cholesterol-fed medium. In study to identify which ginsenosides are responsible for life span restoring effects of GTS, we found that ginsenoside Rc supplement not only restored life span of worms grown in cholesterol-deprived medium but also prolonged life span of worms grown in cholesterol-fed medium. Worms grown in medium supplemented with ginsenoside Rb<SUB>1</SUB> or Rc to cholesterol-deprived medium exhibited strong filipin staining, in which filipin forms tight and specific complexes with 3β-hydroxy sterols. These results show a possibility that ginsenosides could be utilized by <I>C. elegans</I> as a sterol substitute and further indicate that ginsenoside Rc is the component of <I>Panax ginseng</I> that prolongs the life span of <I>C. elegans</I>.</P>

Mutational Analysis of Sonic Hedgehog Gene in Human Fetuses with Holoprosencephaly

Yoon, Sung-Hee,Kim, Kyu-Rae,Shim, Yhong-Hee 한국유전학회 2004 Genes & Genomics Vol.26 No.4

Holoprosencephaly (HPE) is a major developmental defect in the human brain and face. HPE is etiologically heterogeneous, and its formation depends on both genetic and environmental factors. Sonic Hedgehog (SHH) is known to cause HPE in vertebrates. SHH is a secreted protein that plays a critical role in the early development of the forebrain and central nervous system. To determine whether SHH mutations are involved in pathogenesis of HPE in Korea, we performed mutational analysis in 32 prematurely terminated fetuses with HPE at gestational ages from 21 to 33 weeks by PCR-single strand conformation polymorphism analysis and DNA sequencing. Out of 32 HPE cases examined, one novel silent polymorphism was identified in exon 2 of the SHH gene, suggesting that other mechanism(s) might be involved in the pathogenesis of HPE in prematurely terminated fetuses, and indicating the genetic heterogeneity of HPE.