• Molecules and Cells
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• 제21권2호
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• pp.251-260
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• 2006

During mitosis, genomic integrity is maintained by the proper coordination of anaphase entry and mitotic exit via mitotic checkpoints. In budding yeast, mitotic exit is controlled by a regulatory cascade called the mitotic exit network (MEN). The MEN is regulated by a small GTPase, Tem1p, which in turn is controlled by a two-component GAP, Bfa1p-Bub2p. Recent results suggested that phosphorylation of Bfa1p by the polorelated kinase Cdc5p is also required for triggering mitotic exit, since it decreases the GAP activity of Bfa1p-Bub2p. However, the dispensability of GEF Lte1p for mitotic exit has raised questions about regulation of the MEN by the GTPase activity of Tem1p. We isolated a Bfa1p mutant, $Bfa1p^{E438K}$, whose overexpression only partially induced anaphase arrest. The molecular and biochemical functions of $Bfa1p^{E438K}$ are similar to those of wild type Bfa1p, except for decreased GAP activity. Interestingly, in $BFA1^{E438K}$ cells, the MEN could be regulated with nearly wild type kinetics at physiological temperature, as well as in response to various checkpoint-activating signals, but the cells were more sensitive to spindle damage than wild type. These results suggest that the GAP activity of Bfa1p-Bub2p is responsible for the mitotic arrest caused by spindle damage and Bfa1p overproduction. In addition, the viability of cdc5-2 ${\Delta}bfa1 $ cells was not reduced by $BFA1^{E438K}$, suggesting that Cdc5p also regulates Bfa1p to activate mitotic exit by other mechanism(s), besides phosphorylation.

• 한국동물학회지
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• 제15권3호
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• pp.95-100
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• 1972

回復複製(unscheduled DNA synthesis or repair replication)와 染色體交換 및 分裂活動과의 相關關係를 추구하기 위해 X-線을 處理한 4種의 哺乳動物 細胞를 材料로 回復複製 時期와 線量反應을 調査하였다. 回復複製는 調査한 4種의 細胞에서 모두 일어나고 그 率은 照射線量에 比例하며 細胞 種類에 따라 差가 난다. 그러나 回復複製가 일어나는 時期는 細胞 種類에 관계없이 X-線 照射후 2時間까지 지속되고 있다. 또 回復複製의 相對量은 細胞의 種族染色體數, 分裂活動 및 染色體交換率과 직접적인 관련이 없다. 分裂活動能力과 染色體交換은 다 線量에 比例하나 그 率은 逆比例 관계를 나타낸다.

• 대한의생명과학회지
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• 제17권3호
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• pp.197-202
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• 2011

Mitosis count is one of the most helpful morphologic features for distinguishing pulmonary typical carcinoid (TC) from atypical carcinoid (AC). However, identifying areas of highest mitotic activity is tedious and time-consuming, and mitosis count may vary substantially among pathologists. Anti-phosphohistone H3 (PHH3) is an antibody that specifically detects histone H3 only when phosphorylated at serine 10 or serine 28, an event that is concurrent with mitotic chromatin condensation and not observed during apoptosis. In this study, immunohistochemical staining for PHH3 was performed to determine whether PHH3 was a reliable and objective mitosis-specific marker for pulmonary carcinoid tumors. Seventeen cases of surgically resected pulmonary carcinoid tumors (12 TCs and 5 ACs) were obtained and classified according to the 2004 World Health Organization classification. Mitotic counts determined by PHH3 correlated to ones determined by hematoxylin and eosin (H&E) staining; however, PHH3 mitotic counts (mean mitotic counts: 1 in TCs and 3.2 in ACs) were slightly higher than H&E mitotic counts (mean mitotic counts: 0.25 in TCs and 1.8 in ACs). The mitotic counts determined by experienced observer were more correlated to those determined by inexperienced observer with the PHH3-based method (R=0.968, P<0.001) rather than H&E staining (R=0.658, P<0.001). These results suggest that the PHH3 mitotic counting method was more sensitive and simple for detecting mitoses compared to traditional H&E staining. Therefore, PHH3 immunohistochemistry may contribute to more accurate and reproducible diagnosis of pulmonary carcinoid tumors and may be a valuable aid for administrating appropriate clinical treatment.

• BMB Reports
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• 제51권6호
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• pp.261-262
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• 2018

Aurora B is an important kinase involved in dynamic cellular events in mitosis. Aurora B activity is controlled by several post-translational modifications (PTMs). Among them, E3 ubiquitin ligase-mediated ubiquitination plays crucial roles in controlling the relocation and degradation of Aurora B. Aurora B, ubiquitinated by different E3 ligases, moves to the exact site for its mitotic function during metaphase-anaphase transition and is then degraded for cell cycle progression at the end of mitosis. However, how the stability of Aurora B is maintained until its degradation has been poorly understood. Recently, we have found that USP35 acts as a deubiquitinating enzyme (DUB) for Aurora B and affects its stability during cell division, thus being involved in the regulation of mitosis. In this review, we discuss the USP35-mediated deubiquitination of Aurora B and the regulation of mitotic progression by USP35.

• Molecules and Cells
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• 제42권12호
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• pp.840-849
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• 2019

The spatiotemporal mitotic processes are controlled qualitatively by phosphorylation and qualitatively by ubiquitination. Although the SKP1-CUL1-F-box protein (SCF) complex and the anaphase-promoting complex/cyclosome (APC/C) mainly mediate ubiquitin-dependent proteolysis of mitotic regulators, the E3 ligase for a large portion of mitotic proteins has yet to be identified. Here, we report c-Cbl as an E3 ligase that degrades DDA3, a protein involved in spindle dynamics. Depletion of c-Cbl led to increased DDA3 protein levels, resulting in increased recruitment of Kif2a to the mitotic spindle, a concomitant reduction in spindle formation, and chromosome alignment defects. Furthermore, c-Cbl depletion induced centrosome over-duplication and centriole amplification. Therefore, we concluded that c-Cbl controls spindle dynamics and centriole duplication through its E3 ligase activity against DDA3.

• Journal of Ginseng Research
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• 제46권3호
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• pp.481-488
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• 2022

Background: Although the tumor-suppressive effects of ginsenosides in cell cycle have been well established, their pharmacological properties in mitosis have not been clarified yet. The chromosomal instability resulting from dysregulated mitotic processes is usually increased in cancer. In this study, we aimed to investigate the anticancer effects of ginsenoside Rg1 on mitotic progression in cancer. Materials and methods: Cancer cells were treated with ginsenoside Rg1 and their morphology and intensity of different protein were analyzed using immunofluorescence microscopy. The level of proteins in chromosomes was compared through chromosomal fractionation and Western blot analyses. The location and intensity of proteins in the chromosome were confirmed through immunostaining of mitotic chromosome after spreading. The colony formation assays were conducted using various cancer cell lines. Results: Ginsenoside Rg1 reduced cancer cell proliferation in some cancers through inducing mitotic arrest. Mechanistically, it inhibits the phosphorylation of histone H3 Thr3 (H3T3ph) mediated by Haspin kinase and concomitant recruitment of chromosomal passenger complex (CPC) to the centromere. Depletion of Aurora B at the centromere led to abnormal centromere integrity and spindle dynamics, thereby causing mitotic defects, such as increase in the width of the metaphase plate and spindle instability, resulting in delayed mitotic progression and cancer cell proliferation. Conclusion: Ginsenoside Rg1 reduces the level of Aurora B at the centromere via perturbing Haspin kinase activity and concurrent H3T3ph. Therefore, ginsenoside Rg1 suppresses cancer cell proliferation through impeding mitotic processes, such as chromosome alignment and spindle dynamics, upon depletion of Aurora B from the centromere.

• Asian Pacific Journal of Cancer Prevention
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• 제14권6호
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• pp.3669-3676
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• 2013

Faithful transmission of genetic information depends on accurate chromosome segregation as cells exit from mitosis, and errors in chromosomal segregation are catastrophic and may lead to aneuploidy which is the hallmark of cancer. In eukaryotes, an elaborate molecular control system ensures proper orchestration of events at mitotic exit. Phosphorylation of specific tyrosyl residues is a major control mechanism for cellular proliferation and the activities of protein tyrosine kinases and phosphatases must be integrated. Although mitotic kinases are well characterized, phosphatases involved in mitosis remain largely elusive. Here we identify a novel variant of mouse protein tyrosine phosphatase containing domain 1 (Ptpcd1), that we named Ptpcd2. Ptpcd1 is a Cdc14 related centrosomal phosphatase. Our newly identified Ptpcd2 shared a significant homology to yeast Cdc14p (34.1%) and other Cdc14 family of phosphatases. By subcellular fractionation Ptpcd2 was found to be enriched in the cytoplasm and nuclear pellets with catalytic phosphatase activity. By means of immunofluorescence, Ptpcd2 was spatiotemporally regulated in a cell cycle dependent manner with cytoplasmic abundance during mitosis, followed by nuclear localization during interphase. Overexpression of Ptpcd2 induced mitotic exit with decreased levels of some mitotic markers. Moreover, Ptpcd2 failed to colocalize with the centrosomal marker ${\gamma}$-tubulin, suggesting it as a non-centrosomal protein. Taken together, Ptpcd2 phosphatase appears a non-centrosomal variant of Ptpcd1 with probable mitotic functions. The identification of this new phosphatase suggests the existence of an interacting phosphatase network that controls mammalian mitosis and provides new drug targets for anticancer modalities.

• 한국동물학회지
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• 제14권4호
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• pp.175-180
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• 1971

5-AU (5-aminouracil)를 처리하므로써 세포분열의 동시화를 촉진시킨 사람의 신장세포의 분열활동, 염색체 이상 및 DNA복제 양상에 미치는 X-선의 영향을 조직배양 및 자기방사법(autoradiography)을 통하여 추구하였다. 5-AU처리구에서 분열활동의 최고점은 5-AU를 처리한 뒤 10시간에서 나타나며, 대조구에 비해서 6배나 높음을 보여준다. 5-AU 처리후 100R의 X-선을 조사한 실험구에서는 X-선의 영향은 주로 세포분열을 지연시키고 분열활동을 저해시킬 뿐 아니라 분열활동의 최고점을 보여주는 시간을 불규칙하게 한다. 대조구에서 세포당 염색체이상율은 0.030에 불과하나 5-AU를 처리할 경우는 0.147로 높아진다. 한편 5-AU+100R 및 5-AU+200R의 X-선 처리구에서 세포당 염색체 이상율은 각각 0.583 및 0.669로 보다 높아짐을 보겠다. 한편 세포당 1R당 평균 염색체 이상율은 0.0035가 된다. 본 실험결과를 통해 보면 5-AU가 표지된 분열상의 출\ulcorner빈도 및 표지강도를 높이고 있음을 알겠는데, 그것은 5-AU가 세포주기중 S기에 놓인 세포를 축적시키는 힘이 있기때문이라고 보겠다. 이와는 반대로 X-선은 세포의 표지강도와 표지된 분열상의 출현빈도를 저하시킨다.

• Asian-Australasian Journal of Animal Sciences
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• 제2권3호
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• pp.204-205
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• 1989

• 한국미생물·생명공학회지
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• 제50권3호
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• pp.436-440
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• 2022

본 연구에서는 염색체가공기술을 이용하여 xylan으로부터 다양한 대사산물을 생산할 수 있는 유전자를 도입한 효모인 공염색체를 구축하였다. 효율적인 염색체가공기술인 PCS법을 이용하기 위해 염색체 splitting에 필요한 splitting fragment (DNA module)를 각각 제작하였고, xylan 대사에 관여하는 유전자군을 가진 YKY164 균주에 형질전환하였다. 두번의 염색체 splitting에 의해 1,124 kb의 효모 7번염색체는 887 kb-YAC, 45 kb-mini YAC와 198 kb-YAC로 가공되었으며, 총 18개의 염색체를 가진 YKY183 균주를 구축하였다. 염색체가공을 위한 splitting efficiency는 50-78%였으며, 45 kb-mini YAC 상에 있는 외래유전자의 발현 및 효소활성은 염색체가공 전과 비교하여 유의미한 변화 및 저하는 관찰되지 않았다. 또한 생산된 재조합효소에 의한 xylan의 분해산물을 확인하였으며, 160 generation 동안 미니 효모인 공염색체는 염색체의 결실없이 안정적인 mitotic stability를 유지하였다.