• BMB Reports
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• v.53 no.8
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• pp.425-430
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• 2020

Tumor necrosis factor-inducible gene 6 protein (TSG-6) is a cytokine secreted by mesenchymal stem cells (MSCs) and regulates MSC stemness. We previously reported that TSG-6 changes primary human hepatic stellate cells (pHSCs) into stem-like cells by activating yes-associated protein-1 (YAP-1). However, the molecular mechanism behind the reprogramming action of TSG-6 in pHSCs remains unknown. Cluster of differentiation 44 (CD44) is a transmembrane protein that has multiple functions depending on the ligand it is binding, and it is involved in various signaling pathways, including the Wnt/β-catenin pathway. Given that β-catenin influences stemness and acts downstream of CD44, we hypothesized that TSG-6 interacts with the CD44 receptor and stimulates β-catenin to activate YAP-1 during TSG-6-mediated transdifferentiation of HSCs. Immunoprecipitation assays showed the interaction of TSG-6 with CD44, and immunofluorescence staining analyses revealed the colocalization of TSG-6 and CD44 at the plasma membrane of TSG-6-treated pHSCs. In addition, TSG-6 treatment upregulated the inactive form of phosphorylated glycogen synthase kinase (GSK)-3β, which is a negative regulator of β-catenin, and promoted nuclear accumulation of active/nonphosphorylated β-catenin, eventually leading to the activation of YAP-1. However, CD44 suppression in pHSCs following CD44 siRNA treatment blocked the activation of β-catenin and YAP-1, which inhibited the transition of TSG-6-treated HSCs into stem-like cells. Therefore, these findings demonstrate that TSG-6 interacts with CD44 and activates β-catenin and YAP-1 during the conversion of TSG-6-treated pHSCs into stem-like cells, suggesting that this novel pathway is an effective therapeutic target for controlling liver disease.

• Korean Journal of Pharmacognosy
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• v.46 no.1
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• pp.52-58
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• 2015

Neural stem cells (NSCs), with self-renewal and neuronal differentiation capacity, are a feasible resource in cell-based therapies for various neurodegenerative diseases and neural tissue injuries. In this study, we investigated the effects of Schisandrae Fructus (SF) on proliferation and differentiation of human embryonic NSCs. Treatment with 70% ethanol extract of SF increased the viability of NSCs derived from human embryonic stem cells, which was accompanied by increased mRNA expression of cyclin D1. Whereas 70% ethanol extract of SF also decreased the mRNA expression of nestin, it increased class III ${\beta}$-tublin (Tuj-1) and MAP2 in both growth and differentiation media. Lastly, we found increased mRNA expression of BDNF in SF-treated NSCs. In conclusion, our study demonstrates for the first time that SF induced proliferation and neuronal differentiation of NSCs and increased mRNA expression of BDNF, suggesting its potential as a regulator of NSC fate in NSC-based therapy for neuronal injuries from various diseases.

• Molecules and Cells
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• v.43 no.3
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• pp.203-214
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• 2020

Post-translational modifications play major roles in the stability, function, and localization of target proteins involved in the nervous system. The ubiquitin-proteasome pathway uses small ubiquitin molecules to degrade neuronal proteins. Deubiquitinating enzymes (DUBs) reverse this degradation and thereby control neuronal cell fate, synaptic plasticity, axonal growth, and proper function of the nervous system. Moreover, mutations or downregulation of certain DUBs have been found in several neurodegenerative diseases, as well as gliomas and neuroblastomas. Based on emerging findings, DUBs represent an important target for therapeutic intervention in various neurological disorders. Here, we summarize advances in our understanding of the roles of DUBs related to neurobiology.

• Proceedings of the KSAR Conference
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• 2003.06a
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• pp.30-30
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• 2003

The present study examined the developmental ability of embryonic stem (ES) cells aggregated with mouse parthenogenetic embryos. Oocytes obtained from superovulated female mouse (BCF1) were treated with 7% ethanol and 5 $\mu\textrm{g}$/$m\ell$ cytochalasin B (CB) for producing pathenotes and in vitro fertilized with fresh sperm for producing normal embryos. The reporter vector (pNeoEGFP) were inserted into ES cells (129S4/svJae) by electroporation. At the 8-cell stage, in vitro fertilized embryos and pathenotes, which the zona pellucida was removed, were co-cultured with 5~10 ES cells for 4 hr. After in vitro fertilized embryos and parthenotes aggregated with ES cells were incubated to blastocyst stage, and these blastocysts transferred into the uterus of pseudopregnant recipients. The fertilized embryos aggregated with ES cells were successfully developed to offspring, but the parthenotes aggregated with ES cells failed to develop offsprings. However, genomic DNA of ES cells was detected in the pathenogenetic fetus by polymerase chain reactions at 15 day post gestation. In this study, results indicated that parthenotes aggregated with ES cells showed possible development to fetus. In the future, this method may help to produce transgenic chimera from parthenotes aggregated with ES cells.

• The Korean Journal of Physiology and Pharmacology
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• v.27 no.4
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• pp.407-416
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• 2023

The regeneration of myocardium following acute circulatory events remains a challenge, despite numerous efforts. Mesenchymal stem cells (MSCs) present a promising cell therapy option, but their differentiation into cardiomyocytes is a time-consuming process. Although it has been demonstrated that PSME4 degrades acetyl-YAP1, the role of PSME4 in the cardiac commitment of MSCs has not been fully elucidated. Here we reported the novel role of PSME4 in MSCs cardiac commitment. It was found that overnight treatment with apicidin in primary-cultured mouse MSCs led to rapid cardiac commitment, while MSCs from PSME4 knock-out mice did not undergo this process. Cardiac commitment was also observed using lentivirus-mediated PSME4 knockdown in immortalized human MSCs. Immunofluorescence and Western blot experiments revealed that YAP1 persisted in the nucleus of PSME4 knockdown cells even after apicidin treatment. To investigate the importance of YAP1 removal, MSCs were treated with shYAP1 and apicidin simultaneously. This combined treatment resulted in rapid YAP1 elimination and accelerated cardiac commitment. However, overexpression of acetylation-resistant YAP1 in apicidin-treated MSCs impeded cardiac commitment. In addition to apicidin, the universal effect of histone deacetylase (HDAC) inhibition on cardiac commitment was confirmed using tubastatin A and HDAC6 siRNA. Collectively, this study demonstrates that PSME4 is crucial for promoting the cardiac commitment of MSCs. HDAC inhibition acetylates YAP1 and facilitates its translocation to the nucleus, where it is removed by PSME4, promoting cardiac commitment. The failure of YAP1 to translocate or be eliminated from the nucleus results in the MSCs' inability to undergo cardiac commitment.

• IMMUNE NETWORK
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• v.11 no.3
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• pp.135-154
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• 2011

The great discovery of microRNAs (miRNAs) has revolutionized current cell biology and medical science. miRNAs are small conserved non-coding RNA molecules that post-transcriptionally regulate gene expression by targeting the 3' untranslated region of specific messenger RNAs for degradation or translational repression. New members of the miRNA family are being discovered on a daily basis and emerging evidence has demonstrated that miRNAs play a major role in a wide range of developmental process including cell proliferation, cell cycle, cell differentiation, metabolism, apoptosis, developmental timing, neuronal cell fate, neuronal gene expression, brain morphogenesis, muscle differentiation and stem cell division. Moreover, a large number of studies have reported links between alterations of miRNA homeostasis and pathological conditions such as cancer, psychiatric and neurological diseases, cardiovascular disease, and autoimmune disease. Interestingly, in addition, miRNA deficiencies or excesses have been correlated with a number of clinically important diseases ranging from cancer to myocardial infarction. miRNAs can repress the gene translation of hundreds of their targets and are therefore well-positioned to target a multitude of cellular mechanisms. As a consequence of extensive participation in normal functions, it is quite logical to ask the question if abnormalities in miRNAs should have importance in human diseases. Great discoveries and rapid progress in the past few years on miRNAs provide the hope that miRNAs will in the near future have a great potential in the diagnosis and treatment of many diseases. Currently, an explosive literature has focussed on the role of miRNA in human cancer and cardiovascular disease. In this review, I briefly summarize the explosive current studies about involvement of miRNA in various human cancers and cardiovascular disease.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.6
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• pp.2485-2489
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• 2012

Purpose: Notch is an important signaling pathway that regulates cell fate, stem cell maintenance and the initiation of differentiation in many tissues. It has been reported that activation of Notch-1 contributes to tumorigenesis. However, whether Notch signaling might have a role in chemoresistance of prostate cancer is unclear. This study aimed to investigate the effects of Notch-1 silencing on the sensitivity of prostate cancer cells to docetaxel treatment. Methods: siRNA against Notch-1 was transfected into PC-3 prostate cancer cells. Proliferation, apoptosis and cell cycle distribution were examined in the presence or absence of docetaxel by MTT and flow cytometry. Expression of $p21^{waf1/cip1}$ and Akt as well as activation of Akt in PC-3 cells were detected by Western blot and Real-time PCR. Results: Silencing of Notch-1 promoted docetaxel induced cell growth inhibition, apoptosis and cell cycle arrest in PC-3 cells. In addition, these effects were associated with increased $p21^{waf1/cip1}$ expression and decreased Akt expression and activation in PC-3 cells. Conclusion: Notch-1 promotes chemoresistance of prostate cancer and could be a potential therapeutic target.

• Animal cells and systems
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• v.6 no.1
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• pp.69-74
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• 2002

Recent evidence has suggested that trunk neural crest cell generally assumed to have equivalent differentiation potentials, demonstrate differentiation bias along the anterior/posterior axis. In amphibian and fish, neural crest cells give rise to three chromatophore types, melanophores, xantho-phores, and iridophores. Each pigment cell type has distinct characteristics but there is speculation about the cellular plasticity that exists among them. Neural crest cells migrate along specific routes, ventromedially and dorsolaterally. Neural crest cells that travel dorsolaterally are the first cells to begin migration in the axolotl and are the major contributors to the visible pigment pattern. Many factors and mechanisms that are responsible for guiding migratory neural crest cells along potential pathways or determining their fate remain unknown. A single lineage of the crest, which becomes restricted to one of the three pigment cell types, gives us the opportunity to examine the existence of neural crest stem cell populations and cellular plasticity. Study presented here showed results from recent in vitro studies designed to identify parameters influencing differentiation events of individual neural crest-derived pigment cell lineages. Melanophore production from neural crest explants originating from different levels along the anterior/posterior axis of wild type-axolotl embryos were compared and demonstrate that the differentiation of melanophores is enhanced in subpopulation of neural crest treated with forskolin. Forskolin (an adenylate cyclase activator) increases intracellular CAMP concentration and eventually activates the protein kinase-A signaling pathway. Melanophore number, melanin content, and tyrosinase activity in explants taken from the anterior-most region of the crest increased significantly in response to forskolin treatment. This study suggests implications of region specific influences and developmental regulation in the development of pigment pattern.

• The Korean Journal of Physiology and Pharmacology
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• v.24 no.6
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• pp.463-472
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• 2020

Direct reprogramming, also known as a trans-differentiation, is a technique to allow mature cells to be converted into other types of cells without inducing a pluripotent stage. It has been suggested as a major strategy to acquire the desired type of cells in cell-based therapies to repair damaged tissues. Studies related to switching the fate of cells through epigenetic modification have been progressing and they can bypass safety issues raised by the virus-based transfection methods. In this study, a protocol was established to directly convert fully differentiated fibroblasts into diverse mesenchymal-lineage cells, such as osteoblasts, adipocytes, chondrocytes, and ectodermal cells, including neurons, by means of DNA demethylation, immediately followed by culturing in various differentiating media. First, 24 h exposure of 5-azacytidine (5-aza-CN), a well-characterized DNA methyl transferase inhibitor, to NIH-3T3 murine fibroblast cells induced the expression of stem-cell markers, that is, increasing cell plasticity. Next, 5-aza-CN treated fibroblasts were cultured in osteogenic, adipogenic, chondrogenic, and neurogenic media with or without bone morphogenetic protein 2 for a designated period. Differentiation of each desired type of cell was verified by quantitative reverse transcriptase-polymerase chain reaction/western blot assays for appropriate marker expression and by various staining methods, such as alkaline phosphatase/alizarin red S/oil red O/alcian blue. These proposed procedures allowed easier acquisition of the desired cells without any transgenic modification, using direct reprogramming technology, and thus may help make it more available in the clinical fields of regenerative medicine.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.122.2-122.2
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• 2016

Surface topographical cues has been highlighted to control the fate of neural stem cells (NSCs). Herein we developed a hierarchically patterned substrate (HPS) platform for regulating NSC differentiation. The HPS induced cytoskeleton alignment and highly activated focal adhesion in hNSCs as indicated by enhanced expression of focal adhesion proteins such as focal adhesion kinase (FAK) and vinculin. hNSCs cultured on HPS exhibited enhanced neuronal differentiation compared to flat group. We also developed a graphene oxide (GO)-based hierarchically patterned substrates (GPS) that promote focal adhesion formation and neuronal differentiation of hNSCs. Enhanced focal adhesion and differentiation of hNSCs on the HPS was reversed by blocking the ${\beta}1$ integrin binding and mechanotransduction-associated signals including Rho-associated protein kinase (ROCK) and extracellular-regulated kinase (ERK) pathway, which may suggest a potential mechanism of beneficial effects of HPS. In addition, hNSCs on the HPS differentiated into functional neurons exhibiting sodium currents and action potentials as confirmed by whole cell patch-clamping analysis. The hierarchical topography can direct differentiation of NSCs towards functional neurons, and therefore would be an important element for the design of functional biomaterials for neural tissue regeneration applications.