• Clinical and Experimental Reproductive Medicine
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• v.38 no.1
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• pp.1-5
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• 2011

The maturation process of mammalian oocytes accompanies an extensive rearrangement of the cytoskeleton and associated proteins. As this process requires a delicate interplay between the cytoskeleton and its regulators, it is often targeted by various external and internal adversaries that affect the congression and/or segregation of chromosomes. Asymmetric cell division in oocytes also requires specific regulators of the cytoskeleton, including formin-2 and small GTPases. Recent literature providing clues regarding how actin filaments and microtubules interact during spindle migration in mouse oocytes are highlighted in this review.

• The Korean Journal of Cytopathology
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• v.9 no.1
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• pp.89-94
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• 1998

A case of fine needle aspiration cytology of an osteoclastic giant cell tumor of pancreas, which is an uncommon variant of ductal adenocarcinoma, is described. Aspirated tumor cells were characterized by three populations: (1) bland osteoclast like giant cells with multiple small, round nuclei with distinct nucleoli, and abundant cytoplasm, (2) Individually scattered or loosely clustered medium sized mononuclear tumor cells, having fine chromatin, smooth nuclear membrane, often prominent nucleoli, and high N/C ratio, (3) bland or atypical spindle shaped cells. Osteoid like lacy material was also seen on cell block section. The immunohistochemical studies using paraffin embedded cell block section showed positivities for vimentin and lysozyme in both giant and mononuclear turner cells. However, they were negative for cytokeratin, epithelial membrane antigen, S-100 protein, carcinoembryonic antigen, and p53.

• The Korean Journal of Cytopathology
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• v.4 no.1
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• pp.70-73
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• 1993

Giant cell tumor(GCT) occurs very unusually in the rib(less than 1% of GCT). We present the cytologic features of GCT of the rib. It showed multiple cellular clusters composed of characteristic, benign looking osteoclast-like multinucleated giant cells and fibroblast-like mononuclear cells. The multinucleated giant cells contained numerous nuclei (average, 30 to 40 per cell, which were closely packed. The nuclei in giant cells were remarkably uniform and round to oval. The mononuclear, neoplastic stromal cells were elongated and spindle-shaped. There was no cytologically malignant portion in the tumor.

• Journal of Embryo Transfer
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• v.23 no.2
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• pp.127-131
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• 2008

Bone marrow (BM) cell harvesting is a crucial element in the isolation of mesenchymal stem cells (MSCs). A simple method for harvesting cat BM cells is described. The results show that a large number of BM cells can rapidly be harvested from the cat by this simple procedure. MSCs prepared by density-gradient method were spindle-shaped morphology with bipolar or polygonal cell bodies and strongly positive for CD9 and CD44 and negative for CD18 and CD45-like. They were capable of differentiation to adipocytic and osteocytic phenotypes when exposed to appropriate induction media. The advantages of this method are its rapidity, simplicity, low invasiveness, and low donor attrition and good outcome.

• Molecules and Cells
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• v.39 no.9
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• pp.654-662
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• 2016

Almost all eukaryotic proteins are subject to post-translational modifications during mitosis and cell cycle, and in particular, reversible phosphorylation being a key event. The recent use of high-throughput experimental analyses has revealed that more than 70% of all eukaryotic proteins are regulated by phosphorylation; however, the mechanism of dephosphorylation, counteracting phosphorylation, is relatively unknown. Recent discoveries have shown that many of the protein phosphatases are involved in the temporal and spatial control of mitotic events, such as mitotic entry, mitotic spindle assembly, chromosome architecture changes and cohesion, and mitotic exit. This implies that certain phosphatases are tightly regulated for timely dephosphorylation of key mitotic phosphoproteins and are essential for control of various mitotic processes. This review describes the physiological and pathological roles of mitotic phosphatases, as well as the versatile role of various protein phosphatases in several mitotic events.

• Molecules and Cells
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• v.27 no.2
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• pp.135-142
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• 2009

The centrosome, an organelle comprising centrioles and associated pericentriolar material, is the major microtubule organizing center in animal cells. For the cell to form a bipolar mitotic spindle and ensure proper chromosome segregation at the end of each cell cycle, it is paramount that the cell contains two and only two centrosomes. Because the number of centrosomes in the cell is determined by the number of centrioles, cells have evolved elaborate mechanisms to control centriole biogenesis and to tightly coordinate this process with DNA replication. Here we review key proteins involved in centriole assembly, compare two major modes of centriole biogenesis, and discuss the mechanisms that ensure stringency of centriole number.

• The Korean Journal of Cytopathology
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• v.18 no.2
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• pp.170-174
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• 2007

Granular cell tumor is a rare tumor of the soft tissue and this is characterized by proliferation of large cells with granular appearing eosinophilic cytoplasm. We report the imprint cytologic features of a case of granular cell tumor in the left calf of a 52-year-old woman. Microscopic examination showed moderate cellularity. The tumor cells were arranged both as single cells and in clusters. The cells were large polygonal-shaped and they had small round nuclei with finely granular chromatin and occasionally conspicuous nucleoli. The cytoplasm was abundant eosinophilic and granular. Naked nuclei and spindle-shaped tumor cells were occasionally noted. No mitosis and necrosis were present. The background showed cytoplasmic granular materials. The tumor cells showed positivity for S-100 protein. Ultrastructurally, abundant lysosomes were present in the cytoplasm of the tumor cells.

• Journal of Life Science
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• v.32 no.2
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• pp.161-166
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• 2022

Mitosis is a process in which a replicated genome is distributed to two daughter cells, and it is necessary for cell survival and organismal development. During mitosis, the spindle assembly checkpoint (SAC) ensures faithful chromosome segregation by monitoring the kinetochore attachment to the mitotic spindle. Although the SAC mechanism has been extensively studied over the last 30 years, the mechanism by which a single unattached kinetochore activates the SAC remains unclear. The key components of the SAC are Mad1, Mad2, Mad3 (BubR1 in higher eukaryotes), Bub1, Bub3, and Cdc20, which are all required for SAC activation. An essential step for SAC activation is the formation of the Mad2 - Cdc20 complex in the unattached kinetochore, which is kinetically disfavored. Although the mechanism by which Mad2 and Cdc20 are recruited to unattached kinetochores is well-known, it is not clear how they form a complex. Recently, a key mechanism for the formation of the Mad2 - Cdc20 complex has been identified, which is catalyzed by an unattached kinetochore. This supports the evidence that a single unattached kinetochore can activate the SAC signaling. Herein, we discuss the known key mechanism for SAC activation, review the recent studies on SAC, and conclude how their discoveries improved the understanding of mitosis.

• Animal Bioscience
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• v.36 no.5
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• pp.710-719
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• 2023

Objective: The present study investigated whether protodioscin (PD), a steroidal saponin mainly found in rhizome of Dioscorea species, alleviates oxidative stress-induced damage of porcine oocytes during in vitro maturation. Methods: Oocytes were treated with different concentrations of PD (0, 1, 10, 100, and 200 µM) in the presence of 200 µM H₂O₂ during in vitro maturation. Following maturation, spindle morphology and mitogen-activated protein kinase activity was assessed along with reactive oxygen species level, GSH activity, and mRNA expression of endogenous antioxidant genes at the MII stage. On the day 7 after parthenogenetic activation, blastocyst formation rate was calculated and the quality of embryo and mRNA expression of development-related genes was evaluated. Results: Developmental competence was significantly poorer in the 0 µM PD-treated (control) group than in the non-treated (normal) and 10 µM PD-treated (10PD) groups. Although the reactive oxygen species level did not significantly differ between these three groups, the glutathione level and mRNA expression of antioxidant genes (superoxide dismutase 1 [SOD1], SOD2, nuclear factor erythroid 2-related factor 2 [Nrf2], and hemo oxygenase-1 [HO-1]) were significantly higher in the normal and 10PD groups than in the control group. In addition, the percentage of oocytes with defective spindle and abnormal chromosomal alignment was significantly lower and the ratio of phosphorylated p44/42 to total p44/42 was significantly higher in the normal and 10PD groups than in the control group. The total cell number per blastocyst was significantly higher in the 10PD group than in the control group. The percentage of apoptotic cells in blastocysts was highest in the control group; however, the difference was not significant. mRNA expression of development-related genes (POU domain, class 5, transcription factor 1 [POU5F1], caudal type homeobox 2 [CDX2], Nanog homeobox [NANOG]) was consistently increased by addition of PD. Conclusion: The PD effectively improves the developmental competence and quality of blastocysts by protecting porcine oocytes against oxidative stress.

• Clinical and Experimental Reproductive Medicine
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• v.39 no.2
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• pp.58-67
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• 2012

Objective: Previously, we identified that transketolase (Tkt), an important enzyme in the pentose phosphate pathway, is highly expressed at 2 hours of spontaneous maturation in oocytes. Therefore, this study was performed to determine the function of Tkt in meiotic cell cycle regulation, especially at the point of germinal vesicle breakdown (GVBD). Methods: We evaluated the loss-of-function of Tkt by microinjecting Tkt double-stranded RNAs (dsRNAs) into germinal vesicle-stage oocytes, and the oocytes were cultured in vitro to evaluate phenotypic changes during oocyte maturation. In addition to maturation rates, meiotic spindle and chromosome rearrangements, and changes in expression of other enzymes in the pentose phosphate pathway were determined after Tkt RNA interference (RNAi). Results: Despite the complete and specific knockdown of Tkt expression, GVBD occurred and meiosis was arrested at the metaphase I (MI) stage. The arrested oocytes exhibited spindle loss, chromosomal aggregation, and declined maturation promoting factor and mitogen-activated protein kinase activities. The modified expression of two enzymes in the pentose phosphate pathway, Prps1 and Rbks, after Tkt RNAi and decreased maturation rates were amended when ribose-5-phosphate was supplemented in the culture medium, suggesting that the Tkt and pentose phosphate pathway are important for the maturation process. Conclusion: We concluded that Tkt and its associated pentose phosphate pathway play an important role in the MI-MII transition of the oocytes' meiotic cell cycle, but not in the process of GVBD.