Yufen Chung - Academia.edu (original) (raw)

Papers by Yufen Chung

Research paper thumbnail of Isolation of neural stem/progenitor cells by using EGF/FGF1 and FGF1B promoter-driven green fluorescence from embryonic and adult mouse brains

Molecular and Cellular Neuroscience, 2009

Fibroblast growth factor 1 (FGF1) and FGF2 have been shown to maintain the proliferation, self-re... more Fibroblast growth factor 1 (FGF1) and FGF2 have been shown to maintain the proliferation, self-renewal and multipotent capacities of neural stem/progenitor cells (NSPCs) in vitro. FGF1 is unique for binding to all known FGF receptors. In this study, we investigated if exogenous EGF and FGF1 could be used in the isolation of NSPCs from embryonic mouse brains. We demonstrated that EGF/FGF1-responsive cells exhibited lower proliferation rate and neurosphere formation efficiency than EGF/FGF2-responsive NSPCs. However, EGF/ FGF1-responsive mouse brain cells exhibited better neural differentiation capacities than EGF/FGF2responsive NSPCs at E11.5. Using F1BGFP reporter, we further demonstrated that F1BGFP(+) cells showed similar multipotent capacities to CD133(+) NSPCs, and could be induced more efficiently toward neuronal differentiation. Our results suggested that EGF/FGF1-responsive cells from E11.5 mouse brains could selfrenew and have better multipotency than EGF/FGF2-responsive NSPCs. Further, CD133(+) and F1BGFP(+) NSPCs may also represent different subsets of NSPCs during neural development and adult neurogenesis.

Research paper thumbnail of Ciliogenic RFX transcription factors regulate FGF1 gene promoter

Journal of Cellular Biochemistry, 2012

Fibroblast growth factor 1 (FGF1) has been shown to regulate cell proliferation, cell division, a... more Fibroblast growth factor 1 (FGF1) has been shown to regulate cell proliferation, cell division, and neurogenesis. Human FGF1 gene 1B promoter (À540 to þ31)-driven green fluorescence (F1BGFP) was shown to recapitulate endogenous FGF1 gene expression. It can also be used to isolate neural stem/progenitor cells (NSPCs) and glioblastoma stem cells (GBM-SCs) from developing mouse brains and human glioblastoma tissues, respectively. However, the regulatory mechanisms of FGF-1B promoter and F1BGFP(þ) cells are not clear. In this study, we present several lines of evidence to show the roles of ciliogenic RFX transcription factors in the regulation of FGF-1B gene promoter and F1BGFP(þ) cells: (i) RFX1, RFX2, and RFX3 transcription factors could directly bind the 18-bp cis-element (À484 to À467), and contribute to the regulation of FGF1 promoter and neurosphere formation. (ii) We demonstrated RFX2/RFX3 complex could only be detected in the nuclear extract of FGF-1B positive cells, but not in FGF-1B negative cells. (iii) Protein kinase C inhibitors, staurosporine and rottlerin, could decrease the percentage of F1BGFP(þ) cells and their neurosphere formation efficiency through reducing the RFX2/3 complex. (iv) RNA interference knockdown of RFX2 could significantly reduce the percentage of F1BGFP(þ) cells and their neurosphere formation efficiency whereas overexpression of RFX2 resulted in the opposite effects. Taken together, this study suggests ciliogenic RFX transcription factors regulate FGF-1B promoter activity and the maintenance of F1BGFP(þ) NSPCs and GBM-SCs.

Research paper thumbnail of Inducing long-term survival with lasting anti-tumor immunity in treating B cell lymphoma by a combined dendritic cell-based and hydrodynamic plasmid-encoding IL-12 gene therapy

International Immunology, 2003

In a previous study we showed that immunization with dendritic cells (DC) pulsed with idiotype (I... more In a previous study we showed that immunization with dendritic cells (DC) pulsed with idiotype (Id) fused with CD40 ligand (CD40L) could break the tolerance to Id which is expressed on B lymphoma cells and restored the responsiveness of T h cells, and, subsequently, induced IgG antibody response. However, this treatment had no therapeutic effect. In the present study, we found that using a hydrodynamic transfection-based technique, a high level of IL-12 production was noticed as early as 7 h after administering plasmid encoding IL-12 (pIL-12) and persisted at a detectable level for at least 9 days. In evaluating the ef®cacy of DC-based and/or IL-12 gene-based therapy in the treatment of 38C13 B cell lymphoma, it was found that either treatment alone was ineffective. However, a combined treatment induced 100% long-term survival. Furthermore, a long-lasting anti-tumor immunity was induced in these mice which resisted further tumor challenge at 58 days after initial inoculation. The surviving mice showed a strong IFN-g-producing T h cell response and humoral antibody response, but there were no detectable cytotoxic T lymphocytes. The antibody from the immune sera mediated a complement-dependent lysis of tumor cells that was tumor speci®c. Furthermore, immunization of mice with DC-based vaccine and pIL-12 treatment elicited higher levels of anti-Id IgG titer and an enhanced IgG2a response which increased the ef®cacy in mediating 38C13 tumor lysis. On examining the mechanism for this isotype change, we found that IFN-g production by CD4 + T cells is not the only determining factor for achieving a successful therapy. DC-based treatment alone could induce the increase of IFN-g production, but lacked any therapeutic effect. The deciding factor appears to be the abrogation of IL-4 production that was achieved by combing with IL-12 gene therapy. Our study provides a basis for exploring the combined use of cytokines or cytokine genes in DC-based treatment for achieving effective cancer immunotherapy.

Research paper thumbnail of In vitro hepatic differentiation of human mesenchymal stem cells

Hepatology, 2004

This study examined whether mesenchymal stem cells (MSCs), which are stem cells originated from e... more This study examined whether mesenchymal stem cells (MSCs), which are stem cells originated from embryonic mesoderm, are able to differentiate into functional hepatocyte-like cells in vitro. MSCs were isolated from human bone marrow and umbilical cord blood, and the surface phenotype and the mesodermal multilineage differentiation potentials of these cells were characterized and tested. To effectively induce hepatic differentiation, we designed a novel 2-step protocol with the use of hepatocyte growth factor and oncostatin M. After 4 weeks of induction, cuboidal morphology, which is characteristic of hepatocytes, was observed, and cells also expressed marker genes specific of liver cells in a time-dependent manner. Differentiated cells further demonstrated in vitro functions characteristic of liver cells, including albumin production, glycogen storage, urea secretion, uptake of low-density lipoprotein, and phenobarbital-inducible cytochrome P450 activity. In conclusion, human MSCs from different sources are able to differentiate into functional hepatocyte-like cells and, hence, may serve as a cell source for tissue engineering and cell therapy of hepatic tissues. Furthermore, the broad differentiation potential of MSCs indicates that a revision of the definition may be required. (HEPATOLOGY 2004;40:1275-1284.

Research paper thumbnail of The effect of ultra-nanocrystalline diamond films on the proliferation and differentiation of neural stem cells

Biomaterials, 2009

The interaction of ultra-nanocrystalline diamond (UNCD) with neural stem cells (NSCs) has been st... more The interaction of ultra-nanocrystalline diamond (UNCD) with neural stem cells (NSCs) has been studied along with its surface modification in order to improve its function as a biomaterial. Hydrogen-and oxygen-terminated UNCD films were compared with standard grade polystyrene in terms of their impact on the growth, expansion and differentiation of NSCs. When NSCs were cultured on these substrates in low serum and without any differentiating factors, hydrogen-terminated UNCD films spontaneously induced cell proliferation and neuronal differentiation. Oxygen-terminated UNCD films were also shown to further improve neural differentiation, with a preference to differentiate into oligodendrocytes. Hence, controlling the surface properties of UNCD could manipulate the differentiation of NSCs for different biomedical applications. These observations raise the potential for the use of UNCD as a biomaterial for central nervous system transplantation and tissue engineering.

Research paper thumbnail of HumanFGF1promoter is active in ependymal cells and dopaminergic neurons in the brains of F1B‐GFP transgenic mice

Developmental Neurobiology, 2014

FGF1 is involved in multiple biological functions and exhibits the importance in neuroprotective ... more FGF1 is involved in multiple biological functions and exhibits the importance in neuroprotective effects. Our previous studies indicated that, in human brain and retina, the FGF1B promoter controlled the expression of FGF1. However, the exact function and regulation of FGF1 in brain is still unclear. Here, we generated F1B-GFP transgenic mice that expressed the GFP reporter gene under the control of human FGF1B promoter (-540 to +31). Using the fresh brain sections of F1B-GFP transgenic mice, we found that the F1B-GFP cells expressed strong fluorescent signals in the ventricular system throughout the brain. The results of immunohistochemistry further showed that two distinct populations of F1B-GFP(+) cells existed in the brains of F1B-GFP transgenic mice. We demonstrated that one population of F1B-GFP(+) cells was ependymal cells, which distributed along the entire ventricles, and the second population of F1B-GFP(+) cells was neuronal cells that projected their long processes into multiple directions in specific areas of the brain. The double labeling of F1B-GFP(+) cells and tyrosine hydroxylase indicated that a subpopulation of F1B-GFP(+) -neuronal cells was dopaminergic neurons. Importantly, these F1B-GFP(+) /TH(+) cells were distributed in the main dopaminergic neuronal groups including hypothalamus, ventral tegmental area, and raphe nuclei. These results suggested that human FGF1B promoter was active in ependymal cells, neurons, and a portion of dopaminergic neurons. Thus, the F1B-GFP transgenic mice provide an animal model not only for studying FGF1 gene expression in vivo but also for understanding the role of FGF1 contribution in neurodegenerative disorders such as Parkinson's disease and Alzheimer's disease.

Research paper thumbnail of The mood stabilizer valproate activates human FGF1 gene promoter through inhibiting HDAC and GSK-3 activities

Journal of Neurochemistry, 2013

Valproic acid (VPA) is the primary mood-stabilizing drug to exert neuroprotective effects and to ... more Valproic acid (VPA) is the primary mood-stabilizing drug to exert neuroprotective effects and to treat bipolar disorder in clinic. Fibroblast growth factor 1 (FGF1) has been shown to regulate cell proliferation, cell division, and neurogenesis. Human FGF1 gene 1B promoter (-540 to +31)-driven green fluorescence (F1BGFP) has been shown to recapitulate endogenous FGF1 gene expression and facilitates the isolation of neural stem/progenitor cells (NSPCs) from developing and adult mouse brains. In this study, we provide several lines of evidence to demonstrate the underlying mechanisms of VPA in activating FGF-1B promoter activity: (i) VPA significantly increased the FGF-1B mRNA expression and the percentage of F1BGFP(+) cells; (ii) the increase of F1BGFP expression by VPA involves changes of regulatory factor X (RFX) 1-3 transcriptional complexes and the increase of histone H3 acetylation on the 18-bp cis-element of FGF-1B promoter; (iii) treatments of other histone deacetylases (HDAC) inhibitors, sodium butyrate and trichostatin A, significantly increased the expression levels of FGF-1B, RFX2, and RFX3 transcripts; (iv) treatments of glycogen synthase kinase 3 (GSK-3) inhibitor, lithium, or GSK-3 siRNAs also significantly activated FGF-1B promoter; (v) VPA specifically enhanced neuronal differentiation in F1BGFP(+) embryonic stem cells and NSPCs rather than GFP(-) cells. This study suggested, for the first time, that VPA activates human FGF1 gene promoter through inhibiting HDAC and GSK-3 activities.

Research paper thumbnail of Isolation of neural stem/progenitor cells by using EGF/FGF1 and FGF1B promoter-driven green fluorescence from embryonic and adult mouse brains

Molecular and Cellular Neuroscience, 2009

Fibroblast growth factor 1 (FGF1) and FGF2 have been shown to maintain the proliferation, self-re... more Fibroblast growth factor 1 (FGF1) and FGF2 have been shown to maintain the proliferation, self-renewal and multipotent capacities of neural stem/progenitor cells (NSPCs) in vitro. FGF1 is unique for binding to all known FGF receptors. In this study, we investigated if exogenous EGF and FGF1 could be used in the isolation of NSPCs from embryonic mouse brains. We demonstrated that EGF/FGF1-responsive cells exhibited lower proliferation rate and neurosphere formation efficiency than EGF/FGF2-responsive NSPCs. However, EGF/ FGF1-responsive mouse brain cells exhibited better neural differentiation capacities than EGF/FGF2responsive NSPCs at E11.5. Using F1BGFP reporter, we further demonstrated that F1BGFP(+) cells showed similar multipotent capacities to CD133(+) NSPCs, and could be induced more efficiently toward neuronal differentiation. Our results suggested that EGF/FGF1-responsive cells from E11.5 mouse brains could selfrenew and have better multipotency than EGF/FGF2-responsive NSPCs. Further, CD133(+) and F1BGFP(+) NSPCs may also represent different subsets of NSPCs during neural development and adult neurogenesis.

Research paper thumbnail of Ciliogenic RFX transcription factors regulate FGF1 gene promoter

Journal of Cellular Biochemistry, 2012

Fibroblast growth factor 1 (FGF1) has been shown to regulate cell proliferation, cell division, a... more Fibroblast growth factor 1 (FGF1) has been shown to regulate cell proliferation, cell division, and neurogenesis. Human FGF1 gene 1B promoter (À540 to þ31)-driven green fluorescence (F1BGFP) was shown to recapitulate endogenous FGF1 gene expression. It can also be used to isolate neural stem/progenitor cells (NSPCs) and glioblastoma stem cells (GBM-SCs) from developing mouse brains and human glioblastoma tissues, respectively. However, the regulatory mechanisms of FGF-1B promoter and F1BGFP(þ) cells are not clear. In this study, we present several lines of evidence to show the roles of ciliogenic RFX transcription factors in the regulation of FGF-1B gene promoter and F1BGFP(þ) cells: (i) RFX1, RFX2, and RFX3 transcription factors could directly bind the 18-bp cis-element (À484 to À467), and contribute to the regulation of FGF1 promoter and neurosphere formation. (ii) We demonstrated RFX2/RFX3 complex could only be detected in the nuclear extract of FGF-1B positive cells, but not in FGF-1B negative cells. (iii) Protein kinase C inhibitors, staurosporine and rottlerin, could decrease the percentage of F1BGFP(þ) cells and their neurosphere formation efficiency through reducing the RFX2/3 complex. (iv) RNA interference knockdown of RFX2 could significantly reduce the percentage of F1BGFP(þ) cells and their neurosphere formation efficiency whereas overexpression of RFX2 resulted in the opposite effects. Taken together, this study suggests ciliogenic RFX transcription factors regulate FGF-1B promoter activity and the maintenance of F1BGFP(þ) NSPCs and GBM-SCs.

Research paper thumbnail of Inducing long-term survival with lasting anti-tumor immunity in treating B cell lymphoma by a combined dendritic cell-based and hydrodynamic plasmid-encoding IL-12 gene therapy

International Immunology, 2003

In a previous study we showed that immunization with dendritic cells (DC) pulsed with idiotype (I... more In a previous study we showed that immunization with dendritic cells (DC) pulsed with idiotype (Id) fused with CD40 ligand (CD40L) could break the tolerance to Id which is expressed on B lymphoma cells and restored the responsiveness of T h cells, and, subsequently, induced IgG antibody response. However, this treatment had no therapeutic effect. In the present study, we found that using a hydrodynamic transfection-based technique, a high level of IL-12 production was noticed as early as 7 h after administering plasmid encoding IL-12 (pIL-12) and persisted at a detectable level for at least 9 days. In evaluating the ef®cacy of DC-based and/or IL-12 gene-based therapy in the treatment of 38C13 B cell lymphoma, it was found that either treatment alone was ineffective. However, a combined treatment induced 100% long-term survival. Furthermore, a long-lasting anti-tumor immunity was induced in these mice which resisted further tumor challenge at 58 days after initial inoculation. The surviving mice showed a strong IFN-g-producing T h cell response and humoral antibody response, but there were no detectable cytotoxic T lymphocytes. The antibody from the immune sera mediated a complement-dependent lysis of tumor cells that was tumor speci®c. Furthermore, immunization of mice with DC-based vaccine and pIL-12 treatment elicited higher levels of anti-Id IgG titer and an enhanced IgG2a response which increased the ef®cacy in mediating 38C13 tumor lysis. On examining the mechanism for this isotype change, we found that IFN-g production by CD4 + T cells is not the only determining factor for achieving a successful therapy. DC-based treatment alone could induce the increase of IFN-g production, but lacked any therapeutic effect. The deciding factor appears to be the abrogation of IL-4 production that was achieved by combing with IL-12 gene therapy. Our study provides a basis for exploring the combined use of cytokines or cytokine genes in DC-based treatment for achieving effective cancer immunotherapy.

Research paper thumbnail of In vitro hepatic differentiation of human mesenchymal stem cells

Hepatology, 2004

This study examined whether mesenchymal stem cells (MSCs), which are stem cells originated from e... more This study examined whether mesenchymal stem cells (MSCs), which are stem cells originated from embryonic mesoderm, are able to differentiate into functional hepatocyte-like cells in vitro. MSCs were isolated from human bone marrow and umbilical cord blood, and the surface phenotype and the mesodermal multilineage differentiation potentials of these cells were characterized and tested. To effectively induce hepatic differentiation, we designed a novel 2-step protocol with the use of hepatocyte growth factor and oncostatin M. After 4 weeks of induction, cuboidal morphology, which is characteristic of hepatocytes, was observed, and cells also expressed marker genes specific of liver cells in a time-dependent manner. Differentiated cells further demonstrated in vitro functions characteristic of liver cells, including albumin production, glycogen storage, urea secretion, uptake of low-density lipoprotein, and phenobarbital-inducible cytochrome P450 activity. In conclusion, human MSCs from different sources are able to differentiate into functional hepatocyte-like cells and, hence, may serve as a cell source for tissue engineering and cell therapy of hepatic tissues. Furthermore, the broad differentiation potential of MSCs indicates that a revision of the definition may be required. (HEPATOLOGY 2004;40:1275-1284.

Research paper thumbnail of The effect of ultra-nanocrystalline diamond films on the proliferation and differentiation of neural stem cells

Biomaterials, 2009

The interaction of ultra-nanocrystalline diamond (UNCD) with neural stem cells (NSCs) has been st... more The interaction of ultra-nanocrystalline diamond (UNCD) with neural stem cells (NSCs) has been studied along with its surface modification in order to improve its function as a biomaterial. Hydrogen-and oxygen-terminated UNCD films were compared with standard grade polystyrene in terms of their impact on the growth, expansion and differentiation of NSCs. When NSCs were cultured on these substrates in low serum and without any differentiating factors, hydrogen-terminated UNCD films spontaneously induced cell proliferation and neuronal differentiation. Oxygen-terminated UNCD films were also shown to further improve neural differentiation, with a preference to differentiate into oligodendrocytes. Hence, controlling the surface properties of UNCD could manipulate the differentiation of NSCs for different biomedical applications. These observations raise the potential for the use of UNCD as a biomaterial for central nervous system transplantation and tissue engineering.

Research paper thumbnail of HumanFGF1promoter is active in ependymal cells and dopaminergic neurons in the brains of F1B‐GFP transgenic mice

Developmental Neurobiology, 2014

FGF1 is involved in multiple biological functions and exhibits the importance in neuroprotective ... more FGF1 is involved in multiple biological functions and exhibits the importance in neuroprotective effects. Our previous studies indicated that, in human brain and retina, the FGF1B promoter controlled the expression of FGF1. However, the exact function and regulation of FGF1 in brain is still unclear. Here, we generated F1B-GFP transgenic mice that expressed the GFP reporter gene under the control of human FGF1B promoter (-540 to +31). Using the fresh brain sections of F1B-GFP transgenic mice, we found that the F1B-GFP cells expressed strong fluorescent signals in the ventricular system throughout the brain. The results of immunohistochemistry further showed that two distinct populations of F1B-GFP(+) cells existed in the brains of F1B-GFP transgenic mice. We demonstrated that one population of F1B-GFP(+) cells was ependymal cells, which distributed along the entire ventricles, and the second population of F1B-GFP(+) cells was neuronal cells that projected their long processes into multiple directions in specific areas of the brain. The double labeling of F1B-GFP(+) cells and tyrosine hydroxylase indicated that a subpopulation of F1B-GFP(+) -neuronal cells was dopaminergic neurons. Importantly, these F1B-GFP(+) /TH(+) cells were distributed in the main dopaminergic neuronal groups including hypothalamus, ventral tegmental area, and raphe nuclei. These results suggested that human FGF1B promoter was active in ependymal cells, neurons, and a portion of dopaminergic neurons. Thus, the F1B-GFP transgenic mice provide an animal model not only for studying FGF1 gene expression in vivo but also for understanding the role of FGF1 contribution in neurodegenerative disorders such as Parkinson's disease and Alzheimer's disease.

Research paper thumbnail of The mood stabilizer valproate activates human FGF1 gene promoter through inhibiting HDAC and GSK-3 activities

Journal of Neurochemistry, 2013

Valproic acid (VPA) is the primary mood-stabilizing drug to exert neuroprotective effects and to ... more Valproic acid (VPA) is the primary mood-stabilizing drug to exert neuroprotective effects and to treat bipolar disorder in clinic. Fibroblast growth factor 1 (FGF1) has been shown to regulate cell proliferation, cell division, and neurogenesis. Human FGF1 gene 1B promoter (-540 to +31)-driven green fluorescence (F1BGFP) has been shown to recapitulate endogenous FGF1 gene expression and facilitates the isolation of neural stem/progenitor cells (NSPCs) from developing and adult mouse brains. In this study, we provide several lines of evidence to demonstrate the underlying mechanisms of VPA in activating FGF-1B promoter activity: (i) VPA significantly increased the FGF-1B mRNA expression and the percentage of F1BGFP(+) cells; (ii) the increase of F1BGFP expression by VPA involves changes of regulatory factor X (RFX) 1-3 transcriptional complexes and the increase of histone H3 acetylation on the 18-bp cis-element of FGF-1B promoter; (iii) treatments of other histone deacetylases (HDAC) inhibitors, sodium butyrate and trichostatin A, significantly increased the expression levels of FGF-1B, RFX2, and RFX3 transcripts; (iv) treatments of glycogen synthase kinase 3 (GSK-3) inhibitor, lithium, or GSK-3 siRNAs also significantly activated FGF-1B promoter; (v) VPA specifically enhanced neuronal differentiation in F1BGFP(+) embryonic stem cells and NSPCs rather than GFP(-) cells. This study suggested, for the first time, that VPA activates human FGF1 gene promoter through inhibiting HDAC and GSK-3 activities.