We previously showed that Wnt3a could stimulate human embryonic stem （hES） cell proliferation and affect cell fate determination. In the absence of feeder cell--derived factors, hES cells cultured under a feeder-fre...We previously showed that Wnt3a could stimulate human embryonic stem （hES） cell proliferation and affect cell fate determination. In the absence of feeder cell--derived factors, hES cells cultured under a feeder-free condition survived and proliferated poorly. Adding recombinant Wnt3a in the absence of feeder cell derived-factors stimulated hES cell proliferation but also differentiation. In the present study, we further extended our analysis to other Wnt ligands such as Wntl and Wnt5a. While Wntl displayed a similar effect on hES cells as Wnt3a, Wnt5a had little effect in this system. Wnt3a and Wntl enhanced proliferation of undifferentiated hES cells when feeder-derived self-renewal factors and bFGF are also present. To explore the possibility to promote the proliferation of undifferentiated hES cells by activating the Wnt signaling, we overexpressed Wnt3a or Wntl gene in immortalized human adult fibroblast （HAFi） cells that are superior in supporting long-term growth of undifferentiated hES cells than primary mouse embryonic fibroblasts. HAFi cells with or without a Wnt tmnsgene can be propagated indefinitely. Over-expression of the Wnt3a gene significantly enhanced the ability of HAFi feeder cells to support the undifferentiated growth of 3 different hES cell lines we tested. Co-expression of three commonly-used drug selection genes in Wnt3a-overpressing HAFi cells further enabled us to select rare hES clones after stable transfection or transduction. These immortalized engineered feeder cells （W3R） that co-express growth-promoting genes such as Wnt3a and three drug selection genes should empower us to efficiently make genetic modified hES cell lines for basic and translational research.展开更多
Several extrinsic signals such as LIF, BMP and Wnt can support the self-renewal and pluripotency of embryonic stem （ES） cells through regulating the ＂pluripotent genes.＂ A unique homeobox transcription factor, Nan...Several extrinsic signals such as LIF, BMP and Wnt can support the self-renewal and pluripotency of embryonic stem （ES） cells through regulating the ＂pluripotent genes.＂ A unique homeobox transcription factor, Nanog, is one of the key downstream effectors of these signals. Elevated level of Nanog can maintain the mouse ES cell self-renewal independent of LIF and enable human ES cell growth without feeder cells. In addition to the external signal pathways, intrinsic transcription factors such as FoxD3, P53 and Oct4 are also involved in regulating the expression of Nanog. Functionally, Nanog works together with other key pluripotent factors such as Oct4 and Sox2 to control a set of target genes that have important functions in ES cell pluripotency. These key factors form a regulatory network to support or limit each other＇s expression level, which maintains the properties of ES cells.展开更多
Since the creation of intelligent creatures,we are no longer the puppets of the creator.For thousands of years,people have been thinking about the nature and the future of ourselves,and reconstruction of the process o...Since the creation of intelligent creatures,we are no longer the puppets of the creator.For thousands of years,people have been thinking about the nature and the future of ourselves,and reconstruction of the process of life has become the ultimate dream for us.In 1951,William Harvey,a British scientist,elaborated the theory of the structure and function of embryos for the first time in his book'the reproduction of animals',which established the foundation for people to explore the process and the mechanism of embryonic development.展开更多
文摘We previously showed that Wnt3a could stimulate human embryonic stem （hES） cell proliferation and affect cell fate determination. In the absence of feeder cell--derived factors, hES cells cultured under a feeder-free condition survived and proliferated poorly. Adding recombinant Wnt3a in the absence of feeder cell derived-factors stimulated hES cell proliferation but also differentiation. In the present study, we further extended our analysis to other Wnt ligands such as Wntl and Wnt5a. While Wntl displayed a similar effect on hES cells as Wnt3a, Wnt5a had little effect in this system. Wnt3a and Wntl enhanced proliferation of undifferentiated hES cells when feeder-derived self-renewal factors and bFGF are also present. To explore the possibility to promote the proliferation of undifferentiated hES cells by activating the Wnt signaling, we overexpressed Wnt3a or Wntl gene in immortalized human adult fibroblast （HAFi） cells that are superior in supporting long-term growth of undifferentiated hES cells than primary mouse embryonic fibroblasts. HAFi cells with or without a Wnt tmnsgene can be propagated indefinitely. Over-expression of the Wnt3a gene significantly enhanced the ability of HAFi feeder cells to support the undifferentiated growth of 3 different hES cell lines we tested. Co-expression of three commonly-used drug selection genes in Wnt3a-overpressing HAFi cells further enabled us to select rare hES clones after stable transfection or transduction. These immortalized engineered feeder cells （W3R） that co-express growth-promoting genes such as Wnt3a and three drug selection genes should empower us to efficiently make genetic modified hES cell lines for basic and translational research.
文摘Several extrinsic signals such as LIF, BMP and Wnt can support the self-renewal and pluripotency of embryonic stem （ES） cells through regulating the ＂pluripotent genes.＂ A unique homeobox transcription factor, Nanog, is one of the key downstream effectors of these signals. Elevated level of Nanog can maintain the mouse ES cell self-renewal independent of LIF and enable human ES cell growth without feeder cells. In addition to the external signal pathways, intrinsic transcription factors such as FoxD3, P53 and Oct4 are also involved in regulating the expression of Nanog. Functionally, Nanog works together with other key pluripotent factors such as Oct4 and Sox2 to control a set of target genes that have important functions in ES cell pluripotency. These key factors form a regulatory network to support or limit each other＇s expression level, which maintains the properties of ES cells.
基金supported by the National Nature Science of China(3147127791649202)National key R&D program of China(2016YFA0500901)
文摘Since the creation of intelligent creatures,we are no longer the puppets of the creator.For thousands of years,people have been thinking about the nature and the future of ourselves,and reconstruction of the process of life has become the ultimate dream for us.In 1951,William Harvey,a British scientist,elaborated the theory of the structure and function of embryos for the first time in his book'the reproduction of animals',which established the foundation for people to explore the process and the mechanism of embryonic development.
