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Choi, Hong Seo,Lee, Hyun Min,Jang, Young-Joo,Kim, Cheorl-Ho,Ryu, Chun Jeih AlphaMed Press 2013 Stem cells Vol.31 No.12
<P>Self-renewal and pluripotency of human embryonic stem cells (hESCs) are a complex biological process for maintaining hESC stemness. However, the molecular mechanisms underlying these special properties of hESCs are not fully understood. Heterogeneous nuclear ribonucleoprotein A2/B1 (hnRNP A2/B1) is a multifunctional RNA-binding protein whose expression is related to cell proliferation and carcinogenesis. In this study, we found that hnRNP A2/B1 expression was localized to undifferentiated hESCs and decreased upon differentiation of hESCs. hnRNP A2/B1 knockdown reduced the number of alkaline phosphatase-positive colonies in hESCs and led to a decrease in the expression of pluripotency-associated transcription factors OCT4, NANOG, and SOX2, indicating that hnRNP A2/B1 is essential for hESC self-renewal and pluripotency. hnRNP A2/B1 knockdown increased the expression of gene markers associated with the early development of three germ layers, and promoted the process of epithelial-mesenchymal transition, suggesting that hnRNP A2/B1 is required for maintaining the undifferentiated and epithelial phenotypes of hESCs. hnRNP A2/B1 knockdown inhibited hESC proliferation and induced cell cycle arrest in the G0/G1 phase before differentiation via degradation of cyclin D1, cyclin E, and Cdc25A. hnRNP A2/B1 knockdown increased p27 expression and induced phosphorylation of p53 and Chk1, suggesting that hnRNP A2/B1 also regulates the G1/S transition of hESC cell cycle through the control of p27 expression and p53 and Chk1 activity. Analysis of signaling molecules further revealed that hnRNP A2/B1 regulated hESC proliferation in a PI3K/Akt-dependent manner. These findings provide for the first time mechanistic insights into how hnRNP A2/B1 regulates hESC self-renewal and pluripotency.</P>
HBV-trimera 동물모델을 통한 B형 간염 항체의 효능평가에 관한 연구
강영국(Young Kook Kang),장명희(Myeong Hee Jang),김근수(Keun-Soo Kim),오미숙(Mee Sook Oh),김남재(Nam Jae Kim),이병석(Byung Seok Lee),이은나(Eun Na Lee),김성주(Sung Joo Kim),류춘제(Chun Jeih Ryu),홍효정(Hyo Jeong Hong) 한국실험동물학회 2005 Laboratory Animal Research Vol.21 No.1
Humanized Balb/c mice (termed Trimera mice) conditioned by lethal total body irradiation and bone marrow transplantation from NOD/SCID mice have been described to support efficient engraftment of human tissues. To evaluate the efficacy of potential anti-HBV agents in vivo, we, here, describe the development of a mouse Trimera model for human hepatitis B virus (HBV) infection. HBV viremia was induced by transplantation of ex-vivo HBV-infected human liver fragments under the kidney capsule of Trimera mice (HBV-Trimera). The levels of HBV viremia were determined by measuring serum HBV DNA using polymerase chain reaction (PCR) at 10 days after liver transplantation. In order to evaluate the therapeutic potential of two humanized monoclonal antibodies specific to hepatitis B surface antigens, the HBV-Trimera mice were administrated intraperitoneally with anti-HBs antibody (HzSIII) or anti-preS1 antibody (AP301) at days 14 to 17 post-liver transplantation. Treatment of the HBV-Trimera mice with two anti-HBV humanized monoclonal antibodies (HzSIII, AP301) reduced the viral load in their sera in a dose-dependent manner, suggesting that the humanized antibodies will be useful in the prevention and treatment of HBV infection. These results suggest that the HBV-Trimera mice can be used as an animal models for evaluating therapeutic efficacy of anti-HBV agents.
Immunomic Screening of Cell Surface Molecules on Undifferentiated Human Dental Pulp Stem Cells
Hwang, Hyo-In,Lee, Tae-Hyung,Kang, Kyung-Jung,Ryu, Chun-Jeih,Jang, Young-Joo Mary Ann Liebert 2015 STEM CELLS AND DEVELOPMENT Vol.24 No.16
<P>Human adult dental pulp tissue is a source of adult stem cells that have a potential to differentiate into various tissues, although the primary cell suspensions cultured from pulp tissue are mixtures of both stem cell and nonstem cell populations with heterogeneous phenotypes and various differentiation efficiencies. Therefore, cell surface protein markers on dental pulp stem cells are critical for detection and purification of stem cell populations. Yet, little is known about the cell surface molecules that are specifically associated with the undifferentiated and progenitor state of human adult dental pulp stem cells (hDPSCs). Presently, cell surface proteins expressed on hDPSCs were assessed by screening surface molecules specifically expressed on dentinogenic progenitors. Using a decoy immunization strategy, a set of monoclonal antibodies (MAbs) was generated against undifferentiated pulp progenitor cells. Forty-five hybridomas produced MAbs that interacted weakly, if at all, to differentiated pulp cells. Of these, 19 MAbs (18 IgG, 1 IgM) recognized surface molecules on undifferentiated hDPSCs. By multicolor flow cytometric analysis, 40%-60% of newly identified MAb-positive cells were demonstrated to be positive for the CD44 and CD90 mesenchymal markers. When MAb-positive cells were sorted from the heterogeneous pulp cell suspension, mineralization efficiency was increased three to five times compared with MAb-negative cells. The results suggest that the decoy immunization is an efficient method for isolation of MAbs against dentinogenic progenitors. These MAbs will be helpful for identification and enrichment of hDPSCs for efficient dentin regeneration.</P>
Yoon, Sun Ok,Lee, Tae Sup,Kim, Sang Jick,Jang, Myung Hee,Kang, Young Jun,Park, Jae Hyun,Kim, Keun-Soo,Lee, Hyun Sil,Ryu, Chun Jeih,Gonzales, Noreen R.,Kashmiri, Syed V. S.,Lim, Sang Moo,Choi, Chang Wo American Society for Biochemistry and Molecular Bi 2006 The Journal of biological chemistry Vol.281 No.11
Kim, Won-Tae,Seo Choi, Hong,Min Lee, Hyun,Jang, Young-Joo,Ryu, Chun Jeih AlphaMed Press 2014 Stem Cells Vol.32 No.10
<P>B-Cell receptor-associated protein 31 (BAP31) regulates the export of secreted membrane proteins from the endoplasmic reticulum (ER) to the downstream secretory pathway. Previously, we generated a monoclonal antibody 297-D4 against the surface molecule on undifferentiated human embryonic stem cells (hESCs). Here, we found that 297-D4 antigen was localized to pluripotent hESCs and downregulated during early differentiation of hESCs and identified that the antigen target of 297-D4 was BAP31 on the hESC-surface. To investigate the functional role of BAP31 in hESCs, BAP31 expression was knocked down by small interfering RNA. BAP31 depletion impaired hESC self-renewal and pluripotency and drove hESC differentiation into multicell lineages. BAP31 depletion hindered hESC proliferation by arresting cell cycle at G0/G1 phase and inducing caspase-independent cell death. Interestingly, BAP31 depletion reduced hESC adhesion to extracellular matrix (ECM). Analysis of cell surface molecules showed decreased expression of epithelial cell adhesion molecule (EpCAM) in BAP31-depleted hESCs, while ectopic expression of BAP31 elevated the expression of EpCAM. EpCAM depletion also reduced hESC adhesion to ECM, arrested cell cycle at G0/G1 phase and induced cell death, producing similar effects to those of BAP31 depletion. BAP31 and EpCAM were physically associated and colocalized at the ER and cell surface. Both BAP31 and EpCAM depletion decreased cyclin D1 and E expression and suppressed PI3K/Akt signaling, suggesting that BAP31 regulates hESC stemness and survival via control of EpCAM expression. These findings provide, for the first time, mechanistic insights into how BAP31 regulates hESC stemness and survival via control of EpCAM expression.</P>
Lee, Tae-Hyung,Kim, Won-Tae,Ryu, Chun Jeih,Jang, Young-Joo National Research Council of Canada = Conseil nati 2015 Biochemistry and cell biology Vol.93 No.4
<P> Basic fibroblast growth factor (bFGF or FGF-2) is widely used to modulate the proliferation and differentiation of certain cell types. An expression and purification system for recombinant human FGF-2 in Escherichia coli was established for the purpose of securing a continuous supply of this protein. The purified recombinant FGF-2 significantly increased the population of human embryonic stem cells. The optimal concentrations of FGF-2 for cell proliferative induction in various adult stem cells including human dental pulp stem cells, full term human periodontal ligament stem cells, human gingival fibroblasts, mesenchymal stem cells, and osteogenic oseosarcoma were established in a dose-dependent manner. When cells were treated with recombinant FGF-2 for 6 days before osteogenic induction, the mRNA expression of the bone markers was upregulated in cells originated from human dental pulp tissue, indicating that pretreatment with FGF-2 during culture increase stem cell/progenitor population and osteogenic potential. </P>
Kang, Kyung-Jung,Ko, Seon-Yle,Ryu, Chun-Jeih,Jang, Young-Joo Elsevier 2017 Stem cell research Vol.21 No.-
<P><B>Abstract</B></P> <P>Human dental pulp cells are obtained from dental pulp tissue, and have the ability to form dentin and a pulp-like complex. Although adult stem cells have been identified from the primary culture by using specific cell surface markers, the identity of surface markers for the purification of stem cells within the dental pulp population are still unclear. Previously, we had constructed monoclonal antibodies against the undifferentiated cell-specific surface markers of human dental pulp cells (hDPCs) by performing decoy immunization. Among them, a monoclonal antibody against the cell surface antigen of the undifferentiated hDPCs (named UPSA-1) was purified and its heavy and light chain consensus regions were analyzed. The cell surface binding affinity of UPSA-1 mAb on the undifferentiated hDPCs was stronger than that on the differentiated cells. When tunicamycin was applied to hDPSCs during culture, the cell surface binding affinity of the antibody was dramatically decreased, and dentinogenic differentiation was reduced. The purified UPSA-1 antigen band resulting from immunoprecipitation disappeared or shifted down on the SDS-PAGE by deglycosylation. These data suggested that glycosylation on the cell surface might be a marker of an undifferentiated state, and that UPSA-1 mAb might be useful for identifying the carbohydrate moiety on the cell surface of undifferentiated pulp cells.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A surface antigen (UPSA-1) was found on undifferentiated hDPCs. </LI> <LI> Anti-UPSA-1 monoclonal antibody recognized glycosylation moieties of hDPCs. </LI> <LI> Glycosylation of UPSA-1 correlated with the differentiation potential of hDPCs. </LI> </UL> </P>