• Proceedings of the Korean Society of Applied Pharmacology
• /
• 2001.11a
• /
• pp.110-110
• /
• 2001

Histone deacetylase(HDAC), a neuclear enzyme that regulates gene trascription and the assembly of newly synthesized chromatin, has received much attention in recent literature. The explosion of activity in this field has yielded the cloning of a mammalian gene which encodes a complementary histone acetyl trasferases. Several cyclic tetrapeptide inhibitors of HDAC has been reported to affect the hyperacetylation of mammalian and plant histones. Apicidin, a natural product HDAC inhibitor recently isolated at Merck Research Laboratories, induces therapeutic applications as a broad spectrum antiprotozoal agent to multi-drug resistant malaria and a potential antitumor agnet. The biological activity of apicidin appears to be attributable to inhibition of apicocomplexan HDAC at low nanomolar concentrations.

• Development and Reproduction
• /
• v.27 no.3
• /
• pp.159-165
• /
• 2023

The Ruvb-like AAA ATPase1 (Ruvbl1; also known as Pontin) is an evolutionary conserved protein belonging to the adenosine triphosphates associated with diverse cellular activities (AAA+) superfamily of ATPases. Ruvbl1 is a component of various protein supercomplexes and is involved in a variety of cellular activities, including chromatin remodeling, DNA damage repair, and mitotic spindle assembly however, the developmental significance of this protein is unknown and needs detailed investigation. We investigated the developmental significance of Ruvbl1 in multiciliated cells of the Xenopus laevis epidermis since ruvbl1 is expressed in the multiciliated cells and pronephros during X. laevis embryogenesis. The knockdown of ruvbl1 significantly impaired cilia-driven fluid flow and basal body polarity in the X. laevis epidermis compared to control embryos, but did not affect cilia morphology. Our results suggest that Ruvbl1 plays a significant role in embryonic development by regulating ciliary beating; however, further investigation is needed to determine the mechanisms involved.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.6
• /
• pp.2124-2128
• /
• 2010

In this study, we determined effects of the mitogen-activated protein kinase (MAPK) inhibitor, U0126 on meiotic maturation, microtubule organization and actin filament assembly in the porcine oocyte. The phosphorylated MAPK was first detected at 12 h after the initiation of maturation cultures, fully activated at 24h, and remained until metaphase II. Treatment of germinal vesicle (GV) stage oocytes with $20{\mu}M$ U0126 completely blocked MAPK phosphorylation, but germinal vesicle breakdown (GVBD) was normally proceeded. However, the oocytes didn‘t progress to the metaphase I. The inhibition of MAPK resulted in abnormal spindles. In oocytes treated with U0126 after GVBD, polar body extrusion was normal, but the organization of the metaphase plate and chromosome segregation were abnormal. In conclusion, MAPK activity plays an important regulatory role in GV chromatin configuration and meiotic progress in porcine oocyte maturation.

• Molecules and Cells
• /
• v.40 no.9
• /
• pp.621-631
• /
• 2017

Vaccinia-related kinase 1 (VRK1) and VRK3 are members of the VRK family of serine/threonine kinases and are principally localized in the nucleus. Despite the crucial roles of VRK1/VRK3 in physiology and disease, the molecular and functional interactions of VRK1/VRK3 are poorly understood. Here, we identified over 200 unreported VRK1/VRK3-interacting candidate proteins by affinity purification and LC-MS/MS. The networks of VRK1 and VRK3 interactomes were found to be associated with important biological processes such as the cell cycle, DNA repair, chromatin assembly, and RNA processing. Interactions of interacting proteins with VRK1/VRK3 were confirmed by biochemical assays. We also found that phosphorylations of XRCC5 were regulated by both VRK1/VRK3, and that of CCNB1 was regulated by VRK3. In liver cancer cells and tissues, VRK1/VRK3 were highly upregulated and its depletion affected cell cycle progression in the different phases. VRK3 seemed to affect S phase progression and G2 or M phase entry and exit, whereas VRK1 affects G1/S transition in the liver cancer, which could be explained by different interacting candidate proteins. Thus, this study not only provides a resource for investigating the unidentified functions of VRK1/VRK3, but also an insight into the regulatory roles of VRK1/VRK3 in biological processes.

• Korean Journal of Animal Reproduction
• /
• v.20 no.3
• /
• pp.343-351
• /
• 1996

The objectives of this study are to determine cortical granule distribution during in vitro maturation, parthenogenetic activation and in vitro fertilization of oocytes, and to investigate effects of microfilament inhibitor on the cortical granule distribution during in vitro maturation and fertilization of oocytes in the pig, The corti-cal granule distribution were imaged with fluor-escent labeled lectin under laser scanning confocal microscope or detected by transmission electron microscope. At germinal vesicle stage, cortical granule organelles were located around the cell cortex and were present as a relatively thick area on the oolema. Microfilaments were also observed in a thick uniform area around the cell cortex. Following germinal vesicle break down,microfilaments concentrated to the condensed chromatin and cortical granules were observed in the cortex. Treatment with cytochalasin B inhibited microfilament polymerization and prevented movement of cortical granules to the cortex. Cortical granule exudate following sperm penetration was evenly distributed in the entire perivitelline space. Therefore, these results suggested that the microfilament assembly is involved in the distribution, movement and exocytosis of cortical granules during maturation and fertilization of porcine oocytes. (Key words cortical granule, porcine, maturation, fertilization).

• The Korean Journal of Physiology and Pharmacology
• /
• v.10 no.6
• /
• pp.329-335
• /
• 2006

This study was aimed to investigate the nitric oxide (NO)-induced cytotoxic mechanism in PC12 cells. Sodium nitroprusside (SNP), an NO donor, decreased the viability of PC12 cells in dose-and time-dependent manners. SNP enhanced the production of reactive oxygen species (ROS), and gave rise to apoptotic morphological changes including cell shrinkage, chromatin condensation, and DNA fragmentation. Expression of Bax was not affected, whereas Bcl-2 was downregulated in SNP-treated PC12 cells. SNP augmented the release of cytochrome c from mitochondria into cytosol and enhanced caspase -8, -9, and -3 activities. SNP upregulated both Fas and Fas-L, which are known to be components of death receptor assembly. These results suggest that NO induces apoptosis of PC12 cells through both mitochondria-and death receptor-mediated pathways mediated by ROS and Bcl-2 family.

• The Korean Journal of Physiology and Pharmacology
• /
• v.9 no.4
• /
• pp.239-246
• /
• 2005

In the central nervous system, nitric oxide (NO) is associated with many pathological diseases such as brain ischemia, neurodegeneration and inflammation. The epigallocatechin gallate (EGCG), a major compound of green tea, is recognized as protective substance against neuronal diseases. This study is aimed to investigate the effect of EGCG on NO-induced cell death in PC12 cells. Administration of sodium nitroprusside (SNP), a NO donor, decreased cell viability in a dose- and time-dependent manner and induced genomic DNA fragmentation with cell shrinkage and chromatin condensation. EGCG diminished the decrement of cell viability and the formation of apoptotic morphologenic changes as well as DNA fragmentation by SNP. EGCG played as an antioxidant that attenuated the production of reactive oxygen species (ROS) by SNP. The cells treated with SNP showed downregulation of Bcl-2, but upregulation of Bax. EGCG ameliorated the altered expression of Bcl-2 and Bax by SNP. The release of cytochrome c from mitochondria into cytosol and expression of voltage -dependent anion channel (VDAC)1, a cytochrome c releasing channel in mitochondria, were increased in SNP-treated cells, whereas were attenuated by EGCG. The enhancement of caspase-9, preceding mitochondria-dependent pathway, caspase-8 and death receptor-dependent pathway, as well as caspase-3 activities were suppressed by EGCG. SNP upragulated Fas and Fas-L, which are death receptor assembly, whereas EGCG ameliorated the expression of Fas enhanced by SNP. These results demonstrated that EGCG has a protective effect against SNP-induced apoptosis in PC12 cells, through scavenging ROS and regulating the mitocondria- and death receptor-mediated signal pathway. The present study suggest that EGCG might be a natural neuroprotective substance.

• Proceedings of the KSAR Conference
• /
• 2003.06a
• /
• pp.27-27
• /
• 2003

A diversified and concentrative approach of methylation player can be one of the most powerful studies in the understanding of global epigenetic modifications. Previous studies have suggested that DNA methylation contributes to transcriptional silencing through the several DNA methylation-mediated repression systems by hypermethylation, including methyltransferases (DNMTs), DNA methyltransferase association protein 1 (DMAPl), methyl-CpG binding domain (MBD), and histone deacetylases (HDACs). Assembly of these regulatory protein complexes act sequentially, reciprocally, and interdependently on the newly composed DNA strand through S phase. Therefore, these protein complexes have a role in coupling DNA replication to the designed turn-off system in genome. In this study, we attempted to address the role of DNA methylation by the functional analysis of the methyltransferase molecule, we described the involvement of DMAP1 and DNMTs in cell divistion and the effect of their loss. We also described distinct patterns that DMAP1 and DNMTs are spatially reorganized and displaced from condensing chromosomes as cells progress through mitosis in HeLa cell, COS7, and HIH3T3 cell cycle progressions. DNMT1, DNMT3b, and DMAP1 do not stably contact the genetic material during chromosome compaction and repressive expression. These finding show that the loss of activities of DNMTs and DMAP1 occure stage specifically during the cell cycle, may contribute to the integral balance of global DNA methylation. This is consistent with previous studies resulted in decreased histone acetyltransferases and HDACs, and differs from studies resulted in increased histone methyltransferases. Our results suggest that DNA methylation by DNMTs and DMAP1 during mitosis acts to antagonize hypermethylation by which this mark is epigenetical mitotic-specific methylation.

• International Journal of Oral Biology
• /
• v.34 no.1
• /
• pp.7-14
• /
• 2009

Nitric oxide (NO) acts as an intracellular messenger at the physiological level but can be cytotoxic at high concentrations. The cells within periodontal tissues, such as gingival and periodontal fibroblasts, contain nitric oxide syntheses and produce high concentrations of NO when exposed to bacterial lipopolysaccharides and cytokines. However, the cellular mechanisms underlying NO-induced cytotoxicity in periodontal tissues are unclear at present. In our current study, we examined the NO-induced cytotoxic mechanisms in human gingival fibroblasts (HGF). Cell viability and the levels of reactive oxygen species (ROS) were determined using a MTT assay and a fluorescent spectrometer, respectively. The morphological changes in the cells were examined by Diff-Quick staining. Expression of the Bcl-2 family and Fas was determined by RT-PCR or western blotting. The activity of caspase-3, -8 and -9 was assessed using a spectrophotometer. Sodium nitroprusside (SNP), a NO donor, decreased the cell viability of the HGF cells in a dose- and time-dependent manner. SNP enhanced the production of ROS, which was ameliorated by NAC, a free radical scavenger. ODQ, a soluble guanylate cyclase inhibitor, did not block the SNP-induced decrease in cell viability. SNP also caused apoptotic morphological changes, including cell shrinkage, chromatin condensation, and DNA fragmentation. The expression of Bax, a member of the proapoptotic Bcl-2 family, was upregulated in the SNP-treated HGF cells, whereas the expression of Bcl-2, a member of the anti-apoptotic Bcl-2 family, was downregulated. SNP augmented the release of cytochrome c from the mitochondria into the cytosol and enhanced the activity of caspase-8, -9, and -3. SNP also upregulated Fas, a component of the death receptor assembly. These results suggest that NO induces apoptosis in human gingival fibroblast via ROS and the Bcl-2 family through both mitochondrial- and death receptor-mediated pathways. Our data also indicate that the cyclic GMP pathway is not involved in NO-induced apoptosis.