• Proceedings of the Korea Society of Poultry Science Conference
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• 2001.11a
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• pp.40-46
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• 2001

The use of pluripotent stem cells has tremendous advantages for various purposes but these cell lines with proven germ-line transmission have been completely established only in the mouse. Embryonic germ (EG) cell lines are also pluripotent and undifferentiated stem cells established from primordial germ cells (PGCs). This study was conducted to establish and characterize the chicken EG cells derived from gonadal primordial germ cells. We isolated gonadal PGCs from 5.5-day-old (stage 28) White leghorn (WL) embryos and established chicken EG cells lines with EG culture medium supplemented with human stem cell factor (hSCF), murine leukemia inhibitory factor (mLIF), bovine basic fibroblast growth factor (bFGF), human interleukin-11 (hIL-11), and human insulin-like growth factor-I (hIGF-I). These cells grew continuously for 4 months (10 passages) on a feeder layer of mitotically active chicken embryonic fibroblasts. These cells were characterized by screening with the Periodic acid-Shiff＇s reaction, anti-SSEA-1 antibody, and a proliferation assay after several passages. As the results, the chicken EG cells maintained characteristics of undifferentiated stem cells as well as that of gonadal PGCs. When cultured in suspension, the chicken EG cells successfully formed an embryoid body and differentiated into a variety of cell types when re-seeded onto culture dish. The chicken EG cells were injected into blastodermal layer at stage X and dorsal aorta of recipient embryo at stage 14 (incubation of 53hrs) and produced chimeric chickens with various differentiated tissues derived from the EG cells. The germline chimeras were also successfully induced by using EG cells. Thus, Chicken EG cells will be useful for the production of transgenic chickena and for studies of germ cell differentiation and genomic imprinting.

• BMB Reports
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• v.35 no.1
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• pp.87-93
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• 2002

Neural cell survival is an essential concern in the aging brain and many diseases of the central nervous system. Neural transplantation of the stem cells are already applied to clinical trials for many degenerative neurological diseases, including Huntington's disease, Parkinson's disease, and strokes. A critical problem of the neural transplantation is how to reduce their apoptosis and improve cell survival. Neurotrophic factors generally contribute as extrinsic cues to promote cell survival of specific neurons in the developing mammalian brains, but the survival factor for neural stem cell is poorly defined. To understand the mechanism controlling stem cell death and improve cell survival of the transplanted stem cells, we investigated the effect of plausible neurotrophic factors on stem cell survival. The neural stem cell, HiB5, when treated with PDGF prior to transplantation, survived better than cells without PDGF. The resulting survival rate was two fold for four weeks and up to three fold for twelve weeks. When transplanted into dorsal hippocampus, they migrated along hippocampal alveus and integrated into pyramidal cell layers and dentate granule cell layers in an inside out sequence, which is perhaps the endogenous pathway that is similar to that in embryonic neurogenesis. Promotion of the long term-survival and differentiation of the transplanted neural precursors by PDGF may facilitate regeneration in the aging adult brain and probably in the injury sites of the brain.

• Nuclear Engineering and Technology
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• v.55 no.8
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• pp.2905-2918
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• 2023

The valve assembly used in nuclear power plants is important safety-related equipment. In the new standard, the physical attributes are measured using a valve diagnosis test, which is used in the expansion to other non-tested valves using a quantitative test-basis methodology. With a motor-operated actuator, the state of stem's lubrication is related to physical attributes such as the stem factor and the friction coefficient. This study analyzed the numerical transient of fluid and solid lubrication with a squeeze film effect due to the loading rate on the stem and the stem nut using the experimental data. The differential equation that governs the motion mechanism of the stem and stem nut is established and analyzed. The flow rate, the fluid and the solid contact forces are calculated with the friction coefficient. Finally, we found that a change in the friction coefficient results from a change of the shear force in the solid contact mode during the interchange process between the solid contact mode and the fluid contact mode. The qualitative understanding of the squeeze film effect is expanded quantitatively for forces, thread surface distance, velocity, and acceleration, with consideration of the metal solid contact and fluid contact.

• BMB Reports
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• v.51 no.5
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• pp.242-248
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• 2018

Induced pluripotent stem cells (iPSCs) show great promise for replacing current stem cell therapies in the field of regenerative medicine. However, the original method for cellular reprogramming, involving four exogenous transcription factors, is characterized by low efficiency. Here, we focused on using epigenetic modifications to enhance the reprogramming efficiency. We hypothesized that there would be a new reprogramming factor involved in DNA demethylation, acting on the promoters of pluripotency-related genes. We screened proteins that bind to the methylated promoter of Oct4 and identified Zinc finger protein 127 (Zfp127), the functions of which have not yet been identified. We found that Zfp127 binds to the Oct4 promoter. Overexpression of Zfp127 in fibroblasts induced demethylation of the Oct4 promoter, thus enhancing Oct4 promoter activity and gene expression. These results demonstrate that Zfp127 is a novel regulator of Oct4, and may become a potent target to improve cellular reprogramming.

• Journal of Life Science
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• v.6 no.4
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• pp.234-240
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• 1996

A double-stranded RNA binding factor (RBF), characterized as an inhibitor of PKR kinase in our previous study, was evaluated for its RNA binding specificities by RNA gel electrophoretic mobility shift analysis and membrane filter binding assay, RBF displayed affinities for a broad range of RNAs including viral RNAs and synthetic RNAs consiting of stem and loop structures. GC-rich RNA stem helices as short as 11 bp are suggested to represent the minimal binding motif for RBF. RBF binding to all the natural RNAs tested was reversible by poly(I): poly(C) addition, but E. coli 5S RNA was inefficient.

• Journal of Veterinary Clinics
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• v.38 no.6
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• pp.261-268
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• 2021

The study was conducted to evaluate the effects of carboxymethyl chitosan (CMC) on proliferation, migration, and lipopolysaccharide (LPS)-induced inflammatory response in canine bone marrow-derived mesenchymal stem cells (BMSCs). The proliferation and migration of BMSCs were examined after treatment with CMC. The effect of CMC on the mRNA expression of inflammatory cytokines, such as interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, IL-10, and transforming growth factor (TGF)-β, was also evaluated by reverse transcription polymerase chain reaction (RT-PCR). In the proliferation assay, no significant changes were found at all CMC concentrations compared with controls. The migration assay showed that CMC dose-dependently stimulated the migration of BMSCs in normal and LPS-treated conditions. RT-PCR showed that TNF-α and IL-10 expressions were suppressed in the BMSCs after CMC treatment. However, other genes were not affected. Taken together, CMC promoted BMSC migration and inhibited TNF-α and IL-10. Therefore, CMC may be possible to regulate wound healing when mesenchymal stem cells are applied in inflammatory diseases.

• Molecules and Cells
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• v.37 no.4
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• pp.337-344
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• 2014

Adipose-derived stem cells represent a type of mesenchymal stem cells with the attendant capacity to self-renew and differentiate into multiple cell lineages. We have performed a microarray-based gene expression profiling of osteogenic differentiation and found that the transcription factor Sox11 is down-regulated during the process. Functional assays demonstrate that down-regulation of Sox11 is required for an efficient differentiation. Furthermore, results from forced expression of constitutively-active and dominant-negative derivatives of Sox11 indicate that Sox11 functions as a transcriptional activator in inhibiting osteogenesis. Sox11 thus represents a novel regulator of osteogenesis whose expression and activity can be potentially manipulated for controlled differentiation.

• Molecules and Cells
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• v.43 no.11
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• pp.945-952
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• 2020

Hypoxia induces the expression of several genes through the activation of a master transcription factor, hypoxia-inducible factor (HIF)-1α. This study shows that hypoxia strongly induced the expression of two carboxypeptidases (CP), CPA4 and CPE, in an HIF-1α-dependent manner. The hypoxic induction of CPA4 and CPE gene was accompanied by the recruitment of HIF-1α and upregulation in the active histone modification, H3K4me3, at their promoter regions. The hypoxic responsiveness of CPA4 and CPE genes was observed in human adipocytes, human adipose-derived stem cells, and human primary fibroblasts but not mouse primary adipocyte progenitor cells. CPA4 and CPE have been identified as secreted exopeptidases that degrade and process other secreted proteins and matrix proteins. This finding suggests that hypoxia changes the microenvironment of the obese hypoxic adipose tissue by inducing the expression of not only adipokines but also peptidases such as CPA4 and CPE.

• Biomaterials and Biomechanics in Bioengineering
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• v.1 no.3
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• pp.151-162
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• 2014

Genetically-modified mesenchymal stem cells (GM-MSCs) have emerged as promising therapeutic tools for orthopedic degenerative diseases. GM-MSCs have been widely reported that they are able to increase bone and cartilage tissue regeneration not only by secreting transgene products such as growth factors in a long-term manner, also by inducing MSCs into tissue-specific cells. For example, MSCs modified with BMP-2 gene increased secretion of BMP-2 protein resulting in enhancement of bone regeneration, while MSCs with TGF-b gene did cartilage regeneration. In this review, we introduce several growth factors for gene delivery to MSCs and strategies for bone and cartilage tissue regeneration using GM-MSCs. Furthermore, we describe strategies for strengthening GM-MSCs to more intensively induce tissue regeneration by co-delivery system of multiple genes.

• International Journal of Industrial Entomology and Biomaterials
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• v.21 no.2
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• pp.151-155
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• 2010

Protein disulfide isomerase (PDI) catalyzes the oxidation of disulfides and the isomerizatiob of incorrect disulfides in new polypeptides during folding in the oxidizing environment of the endoplasmic reticulum (ER). To increase recombinant protein hSCF (human stem cell factor) production, we have developed expression system using the Bombyx mori PDI (bPDI) as a fusion partner. bPDI gene fusion was found to improve the production of recombinant hSCFs. Thus, we conclude that bPDI gene fusion will be very useful for the large-scale production of biologically active recombinant proteins.