• Proceedings of the KSAR Conference
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• 2005.06a
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• pp.3-8
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• 2005

• Journal of Embryo Transfer
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• v.27 no.4
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• pp.205-209
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• 2012

Transgenic rats and mice are useful experimental animal models for medical research including human disease model studies. Somatic cell nuclear transfer (SCNT) technology is successfully applied in most mammalian species including cattle, sheep, pig and mouse. SCNT is also considered to increase the efficacy of transgenic/knockout mouse and rat production. However, in the area of reproductive biotechnology, the rodent model is inadequate because of technical obstacles in manipulating the oocytes including intracytoplasmic sperm injection and SCNT. In particular, success of rat SCNT is very limited so far. In this review, the history of rodent cloning is described.

• BMB Reports
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• v.49 no.4
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• pp.197-198
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• 2016

Although three different research groups have reported successful derivations of human somatic cell nuclear transfer-derived embryonic stem cell (SCNT-ESC) lines using fetal, neonatal and adult fibroblasts, the extremely poor development of cloned embryos has hindered its potential applications in regenerative medicine. Recently, however, our group discovered that the severe methylation of lysine 9 in Histone H3 in a human somatic cell genome was a major SCNT reprogramming barrier, and the overexpression of KDM4A, a H3K9me3 demethylase, significantly improved the blastocyst formation of SCNT embryos. In particular, by applying this new approach, we were able to produce multiple SCNT-ES cell lines using oocytes obtained from donors whose eggs previously failed to develop to the blastocyst stage. Moreover, the success rate was closer to 25%, which is comparable to that of IVF embryos, so that our new human SCNT method seems to be a practical approach to establishing a pluripotent stem cell bank for the general public as well as for individual patients.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.8
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• pp.1090-1094
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• 2006

Histone acetylation modification is one key mechanism in the regulation of gene activation. In this study, we investigated the global levels of histone H4 acetylation of insulin like growth factor I (IGF1) and growth hormone (GH) genes in the lungs of two somatic cell cloned calves. Data showed the levels of histone H4 acetylation of IGF1 and GH genes vary widely within different gene regions, and, in almost all regions of the two genes, acetylation levels are lower in the aberrant clone than in the normal clone. Thus we suggest that inefficient epigenetic reprogramming in the clone may affect the balance between acetylation and deacetylation, which will affect normal growth and development. These findings will also have implications for improvement of cloning success rates.

• Journal of Veterinary Clinics
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• v.36 no.5
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• pp.253-258
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• 2019

The objective of this study was to analyse the effects of MS-275 (Class I and II histone deacetylase inhibitor) supplementation on the development of porcine in-vitro somatic nuclear transfer embryo production. During in-vitro development, early embryos were exposed to different concentrations of MS-275 (0, $5{\mu}M$, $10{\mu}M$, and $20{\mu}M$). In in-vitro culture supplemented group, the blastocyst development rate was significantly enhanced by $10{\mu}M$ concentration than other groups (24.0% vs. 19.3%, 21.8%, 11.5%; P < 0.05). Additionally, the 6 h supplementation group, significantly improved the blastocysts production than 24 h, 48 h and control groups (26.1% vs. 17.0%, 15.2%, 2.8%; P < 0.05). Following supplementation with optimal concentrations and time ($10{\mu}M$-6 h group), the blastocyst production was significantly higher than control (25.7% vs 15.8%; P < 0.05). The optimal concentrations of MS-275 significantly enhanced the percentages of ICM:TE than control (43.6% vs. 38.4%; P < 0.05) accompanied with significantly higher expression levels of reprogramming related genes (POU5F1, Naong, and SOX2). In conclusion, the optimal concentrations of $10{\mu}M$ MS-275 and 6 h supplementation during in-vitro culture can significantly improve the quality of porcine in-vitro somatic nuclear transfer embryos through histone acetylation and epigenetic modification. Increasing the efficiency of clonal animal production will greatly promote the development of animal disease models and xenotransplantation.

• BMB Reports
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• v.54 no.10
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• pp.505-515
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• 2021

Human pluripotent stem cells (hPSCs) include human embryonic stem cells (hESCs) derived from blastocysts and human induced pluripotent stem cells (hiPSCs) generated from somatic cell reprogramming. Due to their self-renewal ability and pluripotent differentiation potential, hPSCs serve as an excellent experimental platform for human development, disease modeling, drug screening, and cell therapy. Traditionally, hPSCs were considered to form a homogenous population. However, recent advances in single cell technologies revealed a high degree of variability between individual cells within a hPSC population. Different types of heterogeneity can arise by genetic and epigenetic abnormalities associated with long-term in vitro culture and somatic cell reprogramming. These variations initially appear in a rare population of cells. However, some cancer-related variations can confer growth advantages to the affected cells and alter cellular phenotypes, which raises significant concerns in hPSC applications. In contrast, other types of heterogeneity are related to intrinsic features of hPSCs such as asynchronous cell cycle and spatial asymmetry in cell adhesion. A growing body of evidence suggests that hPSCs exploit the intrinsic heterogeneity to produce multiple lineages during differentiation. This idea offers a new concept of pluripotency with single cell heterogeneity as an integral element. Collectively, single cell heterogeneity is Janus-faced in hPSC function and application. Harmful heterogeneity has to be minimized by improving culture conditions and screening methods. However, other heterogeneity that is integral for pluripotency can be utilized to control hPSC proliferation and differentiation.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.2
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• pp.266-277
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• 2014

Somatic cell nuclear transfer (SCNT) has generally demonstrated that a differentiated cell can convert into a undifferentiated or pluripotent state. In the SCNT experiment, nuclear reprogramming is induced by exposure of introduced donor nuclei to the recipient cytoplasm of matured oocytes. However, because the efficiency of SCNT still remains low, a combination of SCNT technique with the ex-ovo method may improve the normal development of SCNT embryos. Here we hypothesized that treatment of somatic cells with extracts prepared from the germinal vesicle (GV) stage Siberian sturgeon oocytes prior to their use as nuclear donor for SCNT would improve in vitro development. A reversible permeability protocol with $4{\mu}g/mL$ of digitonin for 2 min at $4^{\circ}C$ in order to deliver Siberian sturgeon oocyte extract (SOE) to porcine fetal fibroblasts (PFFs) was carried out. As results, the intensity of H3K9ac staining in PFFs following treatment of SOE for 7 h at $18^{\circ}C$ was significantly increased but the intensity of H3K9me3 staining in PFFs was significantly decreased as compared with the control (p<0.05). Additionally, the level of histone acetylation in SCNT embryos at the zygote stage was significantly increased when reconstructed using SOE-treated cells (p<0.05), similar to that of IVF embryos at the zygote stage. The number of apoptotic cells was significantly decreased and pluripotency markers (Nanog, Oct4 and Sox2) were highly expressed in the blastocyst stage of SCNT embryos reconstructed using SOE-treated cells as nuclear donor (p<0.05). And there was observed a better development to the blastocyst stage in the SOE-treated group (p<0.05). Our results suggested that pre-treatment of cells with SOE could improve epigenetic reprogramming and the quality of porcine SCNT embryos.

• Proceedings of the KSAR Conference
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• 2003.06a
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• pp.39-39
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• 2003

Methylation of DNA 5-cytosine in mammalian early embryo affects great deal in nuclear reprogramming and chromatin remodeling of developing embryo. Current efforts to clone and produce cloned animals including transgenic animals face various problems including low birth rate, irregular development, and so on. In this report, cDNA for the one of house keeping methyltransfcrase, Dnmt1 was cloned from bovine somatic tissues and was analyzed for its nucleotide sequences to investigate the structure and function of the gene in bovine early development. Nucleotide sequence of bovine Dnmt1 homologue showed 76.8% identity with that of human Dnmtl and 66.4% with mouse Dnmt1. Translated amino acid sequence showed 88.4% homology with human homologue and 75.8% homology with mouse counterpart. Three types of Dnmt1 are reported in mouse and human, and are likely present in bovine tissues. Understanding of role of Dnmt1 in bovine development may shed a light in the field of animal, especially bovine cloning.

• Journal of Embryo Transfer
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• v.33 no.4
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• pp.229-235
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• 2018

Polo-like kinase 1 (Plk1) has been known to be a critical element in cell division including centrosome maturation, cytokinesis and spindle formation in somatic, cancer, and mammalian embryonic cells. In particular, Plk1 is highly expressed in cancer cells. Plk1 inhibitors, such as BI2536, have been widely used to prevent cell division as an anticancer drug. In this study, the fertilized murine oocytes were treated with BI2536 for 30 min after recovery from the oviduct to investigate the effect of down-regulation of Plk1 in the in vivo-fertilized murine embryos. Then, the localization and expression of Plk1 was observed by immunofluorescence staining. The sperm which had entered into the oocyte cytoplasm did not form male pronuclei in BI2536-treated oocytes. The BI2536-treated oocytes showed significantly lower expression of Plk1 than non-treated control group. In addition, alpha-tubulin and Plk1 gathered around sperm head in non-treated oocytes, while BI2536-treated oocytes did not show this phenomenon. The present study demonstrates that the Plk1 inhibitor, BI2536, hinders fertilization by inhibiting the formation of murine male pronucleus.

• International Journal of Stem Cells
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• v.17 no.2
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• pp.194-203
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• 2024

Evaluating cell metabolism is crucial during pluripotent stem cell (PSC) differentiation and somatic cell reprogramming as it affects cell fate. As cultured stem cells are heterogeneous, a comparative analysis of relative metabolism using existing metabolic analysis methods is difficult, resulting in inaccuracies. In this study, we measured human PSC basal metabolic levels using a Seahorse analyzer. We used fibroblasts, human induced PSCs, and human embryonic stem cells to monitor changes in basal metabolic levels according to cell number and determine the number of cells suitable for analysis. We evaluated normalization methods using glucose and selected the most suitable for the metabolic analysis of heterogeneous PSCs during the reprogramming stage. The response of fibroblasts to glucose increased with starvation time, with oxygen consumption rate and extracellular acidification rate responding most effectively to glucose 4 hours after starvation and declining after 5 hours of starvation. Fibroblasts and PSCs achieved appropriate responses to glucose without damaging their metabolism 2~4 and 2~3 hours after starvation, respectively. We developed a novel method for comparing basal metabolic rates of fibroblasts and PSCs, focusing on quantitative analysis of glycolysis and oxidative phosphorylation using glucose without enzyme inhibitors. This protocol enables efficient comparison of energy metabolism among cell types, including undifferentiated PSCs, differentiated cells, and cells undergoing cellular reprogramming, and addresses critical issues, such as differences in basal metabolic levels and sensitivity to normalization, providing valuable insights into cellular energetics.