• Journal of Plant Biotechnology
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• 제44권4호
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• pp.409-415
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• 2017

JA는 병원균과 곤충에 대한 방어기작 뿐만 아니라 식물 노화에도 관여하는 식물 호르몬이다. Basic helix-loop-helix 전사인자인 MYC2는 JA의 신호전달반응의 핵심조절자 역할을 하는 것으로 알려져 있다. 본 연구에서는 현사시나무에서 MYC2 유전자를 분리하고 발현특성을 조사하였으며, 다양한 환경 스트레스에 대한 내성을 갖는 임목을 생산하기 위하여 MYC2를 과발현시킨 현사시나무를 개발하였다. 포트에 식재된 MYC2 과발현 현사시나무는 대조구에 비해 잎 노화 표현형이 지연되는 특징을 보였으며, 엽록소 손실이 적은 것으로 나타났다. 또한 가을의 온도 및 광 주기 조건에서 MYC2 과발현 현사시나무의 광화학 효율을 측정한 결과 대조구보다 높은 특징을 보였다. 따라서 현사시나무의 MYC2 유전자가 낙엽이 지는 가을 동안에도 지속적인 생장을 가능하게 하여 임목의 바이오매스를 증진시키는데 기여할 수 있을 것으로 판단된다.

• 한국동물학회지
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• 제38권2호
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• pp.196-203
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• 1995

The c-myc proto-oncogene, one of the immediately earlY genes, is expressed in various mammalian cell types and heavily involved in the regulation of cell proliferation and differentiation. To determine endogeneous expression pattern of c-myc gene in preimpBantation mouse embwos, we employed a reverse transcription coupled to polvrnerase chain reaction (RT-PCR). Transcript of c-myc was detected at fertilized embryos as a maternal transcript. At the early two-cell stave, transcript of c-myc gene was hardly detected, bu, appeared at late two-cell embryos as a zygotic transcript. The level of c-myc expresion was increased at later stases and peaked at blastocvst stage. To examine the functional role of promoter region for c-myc gene transcription, we fused the 5'upstream region (1.8 kb) including econ 1 of c-myc genomic DNA with E. coli lacE gene fnamed as pcMYC-laczl. pcMYC-lacZ was microiniected into the pronscleus of mouse one-cell embryovs, and p·salactosidase activity was determined tv histochemical staining with X-gal at different stases. f-galactosidase activity was detected only at blastocyst, but not at the earlier stage embryos. This result indicates that c-myc gene is transcriptionallv active during mouse preimplantation development.

• 한국자원식물학회지
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• 제30권3호
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• pp.265-271
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• 2017

In this study, we elucidated the molecular mechanism of silymarin by which silymarin may inhibits cell proliferation in human colorectal cancer cells in order to search the new potential anti-cancer target associated with the cell growth arrest. Silymarin reduced the level of c-Myc protein but not mRNA level indicating that silymarin-mediated downregulation of c-Myc may result from the proteasomal degradation. In the confirmation of silymarin-mediated c-Myc degradation, MG132 as a proteasome inhibitor attenuated c-Myc degradation by silymarin. In addition, silymarin phosphorylated the threonine-58 (Thr58) of c-Myc and the point mutation of Thr58 to alanine blocked its degradation by silymarin, which indicates that Thr58 phosphorylation may be an important modification for silymarin-mediated c-Myc degradation. We observed that the inhibition of ERK1/2, p38 and $GSK3{\beta}$ blocked the Thr58 phosphorylation and subsequent c-Myc degradation by silymarin. Finally, the point mutation of Thr58 to alanine attenuated silymarin-mediated inhibition of the cell growth. The results suggest that silymarin induces the cell growth arrest through c-Myc proteasomal degradation via ERK1/2, p38 and $GSK3{\beta}-dependent$ Thr58 phosphorylation.

• 대한미생물학회지
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• 제22권2호
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• pp.167-174
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• 1987

N-myc, a DNA sequence related to the oncogene c-myc, was found to be amplified in untreated primary neuroblastomas and the amplification appeared to be associated with advanced disease at diagnosis and rapid tumor progression. Synthetic peptides have been useful immunogens for generating antisera and monoclonal antibodies to a number of native proteins. In order to identify myc-related protein in the tumor cells, an antiserum against a synthetic hexapeptide (-Glu-Asp-Ile-Trp-Lys-Lys-), whose sequence corresponds to a part of the exon 2 of oncogene N-myc, was prepared by immunizing a rabbit with BSA-conjugated peptide. After ammonium sulfate precipitation and affinity column chromatography, it appeared to be specific to the peptide. Strong nuclear staining in immunoperoxidase method using this serum was observed in both human promyeloid leukemic cell line, HL-60(containing high c-myc copy number), and human neuroblastoma cell line, LA-N-5 (containing high N-myc copy number), whereas LA351 (human lymphoid cell line) cells did not react with the serum. This reaction was completely abrogated by incubating the antiserum with soluble excess peptide. These data suggest that the protein encoded by N-myc could be localized in the nucleus as c-myc protein and this antiserum can be used to detect myc-related tumor cells in clinical samples and to determine if the N-myc expression correlates with genomic amplification in cell lines, untreated primary tumors, and untreated metastases.

• 한국동물학회지
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• 제38권4호
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• pp.550-556
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• 1995

c-myc proto-oncogene은 여러 세포들의 분화와 형질전화에 뿐만 아니라 정상세포의 분열조절에도 관여한다고 알려져왔다. 특히 생쥐의 초기배아에서 c-myc mRNA가 발현되고 antisense c-myc oligomer의 미세주입에 의해 배발생이 억제된다는 연구결과는 c-myc이 초기배아의 발생 및 분열에 관여하는 것을 시사한다. 그러나 최근까지 초기배아에 존재하는 c-myc promoter의 기능적 활성화에 관한 연구는 미진하였다. 이를 위하여, c-myc promoter와 대장균의 lacZ 유전자를 결합시킨 두 종류의 vector(pcmyc-Gall, pcmyc-Ga12)를 만들어 수정란의 전핵에 미세주입한 후, 배 발생에 따른 c-myc promoter의 활성화를 lacZ 유전자의 산물인 $\beta$-galactosidase 에 의한 X-gal 염색으로 조사하였다. 미세주입된 초기 배아는 2세포기 배아를 포함하는 여러 발생단계에서 $\beta$-galactosidase 의 활성을 보였다. 이는 c-myc 유전자가 배아의 게놈유전자로부터 발현되며, 또한 궁극적으로 초기 배아의 발생과정에 중요한 역할을 하고 있음을 시사하고 있다.

• Molecules and Cells
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• 제20권2호
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• pp.157-166
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• 2005

The c-myc proto-oncogene encodes a nuclear protein that is deregulated and/or mutated in most human cancers. Acting primarily as an activator and sometimes as a repressor, MYC protein controls the synthesis of up to 10-15% of genes. The key MYC targets contributing to oncogenesis are incompletely enumerated and it is not known whether pathology arises from the expression of physiologic targets at abnormal levels or from the pathologic response of new target genes that are not normally regulated by MYC. Regardless of which, available evidence indicates that the level of MYC expression is an important determinant of MYC biology. The c-myc promoter has architectural and functional features that contribute to uniform expression and help to prevent or mitigate conditions that might otherwise create noisy expression. Those features include the use of an expanded proximal promoter, the averaging of input from dozens of transcription factors, and real-time feedback using the supercoil-deformable Far UpStream Element (FUSE) as physical sensor of ongoing transcriptional activity, and the FUSE binding protein (FBP) as well as the FBP interacting repressor (FIR) as effectors to enforce normal transcription from the c-myc promoter.

• 생명과학회지
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• 제5권3호
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• pp.105-116
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• 1995

To investigate genomic changes in c-myc gene by a chemical carcinogen, human lymphoblast NC-37 cells were exposed to benzo(a)pyrene(BP) and dimethylbenzanthracene(DMBA), and the c-myc gene expression was evaluated by Northern and Southern blot hybridization techniques. The results are as follows: When the genomic DNA of NC-37 cells exposed to several concentrations(1.25, 2.5 and 5ug/ml) of BP concentration. However, the c-myc gene was most significantly enhanced with 2.5ug/ml of BP. The expressions of c-myc gene in NC-37 cells was stimulated by BP and DMBA. Addition of TPA reduced the gene expression BP-treated cells, whereas it enhanced the gene expression in DMBA-treated cells. The expression of c-H-ras gene was slightly increased by treatment with BP and DMBA alone and in combination with TPA, however the magnitude of increase was not significantly different between each other. The expressions of c-myc c-H-ras genes in Burkitt's lymphoma cells were greater than those in NC-37 cells. When the DNA extracted from NC-37 cells exposed to various concentrations of BP were amplified by polymerase chain reaction using a primer set containing c-myc exon I, the amplified products were of the same size in all groups. To evaluate the BP toxicity in E.coli to which human c-myc gene-cloned pBR322 vector was inserted, Southern blot hybridization was conducted on c-myc genes digested with EcoRI/HindIII and Smal/Xbal restriction enzymes, and observing that in 2 ug/ml BP-treated cells a 3.5kb fragment was generated in addition to 1.3kb fragment which can be observed in normal cells. Direct nucleotide sequence analysis of polymerase chain reaction products showed a mutation of G$\longrightarrow$A transition at the Smal recognition site.

• BMB Reports
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• 제31권4호
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• pp.333-338
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• 1998

The sphingomyelin cycle and ceramide generation have been recognized as potential growth suppression signals in mammalian cells. Ceramide has been shown to induce differentiation, cell growth arrest, senescence, and apoptosis. Although the intracelluar target for the action of ceramide remains unknown, recent studies have demonstrated the role of cytosolic ceramideactivated protein phosphatase(CAPP). In this study, the cytotoxic effect of C2-ceramide, a synthetic cellpermeable ceramide analog, on HEp-2 cells and the mechanism by which ceramide induces cell death were investigated. The addition of exogenous C2-ceramide resulted in a concentration dependent cell death. Okadaic acid, a potent inhibitor of CAPP, enhanced ceramide-mediated cell death, which suggests that CAPP is not involved in this process. To understand the mechanism of action of ceramide, we studied the relationship between ceramide and c-Myc and pRb which are defined components of cell growth regulation. Western blot analyses revealed that C2-ceramide (10${\mu}M$) induced c-Myc down-regulation, but there were no significant changes in pRb. However, treatment of okadaic acid (10 nM) enhanced c-Myc and pRb down-regulation. Reduction of the amount of c-Myc and pRb occurred during HEp-2 cell death. These results suggest that the cytotoxic effect of ceramide in HEp-2 cells may not be mediated through the action of CAPP and that the downstream target for ceramide is c-Myc and pRb.

• 한국동물학회지
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• 제39권4호
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• pp.352-361
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• 1996

내인성 암원유전자인 c-myc유전자는 세포의 증식과 분화에 밀접한 연관되어 있으며, 그의 생물학적인 기능은 이형결합체인 myn과의 결합을 통해서 이루어진다. 본 연구에서는 착상전 생쥐 배아에서의 내인성 c-myc 유전자와 myn 유전자의 발현을 조사하기 위하여 RT-PCR 방법을 이용하였다. myn 유전자 산물은 배아 발생시기를 거쳐서 균일하게 발현된 반면,c-myc 유전자의 발현은 차후 포배기 시기까지 상당한 양으로 증가1세포기에 측정된 후,2세포기에 들어 현저하게 줄었으나, 차후 포배기 시기까지 상당한 양으로 증가하였다. 이러한 c-myc과 myn유전자발현의 비균등한 조화가 중요한 역할을 할 것으로 사료된다. 착상전 생쥐 초기배아 발생 과정에서의 myn 유전자의 기능을 알아 보고자, myn에 대한 antisense oligouncleotides(Myn2, Myn3)를 1세포기이 수정란에 미세주입하였다. Myn2와 Myn3의 미세주입에 의해 상실기/포배기의 변이 시기에 비정상적인 발생이 야기되었다. 이사의 결과로, c-myc은 그의 이형결합체인 myn과 함께 착상전 생쥐 초기배아에서의 중요한 역할을 할 것으로 사료된다.

• Asian Pacific Journal of Cancer Prevention
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• 제15권14호
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• pp.5529-5533
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• 2014

Background: The aim of this study was to investigate the effect of a c-myc antisense oligodeoxynucleotide and 5-fluorouracil on the expression of c-myc, invasion and proliferation of HEPG-2 liver cancer cells. Materials and Methods: HEPG-2 cells were treated with lipiosome-mediated c-myc ADSON and 5-fluorouracil. The proliferation inhibition rate and invasion were measured by MTT and invasion assay, respectively. Cell apoptosis was detected by flow cytometry and expression of c-myc by RT-PCR and immunohistochemistry. Results: The proliferation inhibition rate was significantly higher in the antisense oligodeoxynucleotide added-5-fluorouracil group than single antisense oligodeoxynucleotide or 5-fluorouracil group (p<0.05). G0/G1 cells in the antisense oligodeoxynucleotide group and S cells in the 5-fluorouracil groups were significantly increased than that in the control group, respectively (P<0.01). The amplification strips of PCR products in 5-FU, ASODN and combination groups were significantly weaker than that in the control group (P<0.01). The percentage of c-myc-protein-positive cells were significantly lower in antisense oligodeoxynucleotide, 5-fluorouracil and combination groups than that in the control group (P<0.01). Conclusions: A liposome-mediated c-myc antisense oligodeoxynucleotide and 5-fluorouracil can inhibit the proliferation and invasion of liver cancer cells by reducing the expression of c-myc. A c-myc antisense oligodeoxynucleotide can increase the sensitivity of liver cancer cells to 5-fluorouracil and decrease the dosage of the agent necessary for efficacy, providing an experimental basis for the clinical therapy of liver cancer.