Project description:Like embryonic stem cells, induced pluripotent stem cells (iPSCs) can differentiate into all three germ layers in an in vitro system. Here, we developed a new technology for obtaining neural stem cells (NSCs) from iPSCs through chimera formation, in an in vivo environment. iPSCs contributed to the neural lineage in the chimera, which could be efficiently purified and directly cultured as NSCs in vitro. The iPSC-derived, in vivo-differentiated NSCs expressed NSC markers, and their gene-expression pattern more closely resembled that of brain-derived NSCs than in vitro-differentiated NSCs. This system could be applied for differentiating pluripotent stem cells into specialized cell type whose differentiation protocols are not well established.
Project description:Functional-assay limitations are an emerging issue in characterizing human pluripotent stem cells (hPSCs). With rodent PSCs, chimera formation, using pre-implantation embryos, is the gold-standard assay of pluripotency. In hPSCs, this can only be monitored via teratoma formation or in vitro differentiation, as ethical concerns preclude generation of human-animal chimera. To circumvent this issue, we established a functional assay utilizing interspecific blastocyst injection and in vitro culture (interspecies in vitro chimera assay). The assay uses mouse pre-implantation embryos and human PSCs to make interspecies chimeras cultured in vitro to the early egg cylinder stage. When hiPSCs, both conventional and naive type, which called M-bM-^@M-^\reset cellM-bM-^@M-^], were injected into mouse embryos and cultured. The cells were never integrated into the epiblast of egg cylinder stage-embryo. These results suggest that hPSCs, including naM-CM-/ve type, are unable to form chimera with mouse embryo. Reset cells were converted from conventional human iPSC line PB004, and then compared their gene expression profile with or without transgene overexpression induced by doxycyclin treatment.
Project description:The neural fate commitment of pluripotent stem cells requires repression of extrinsic inhibitory signals and activation of intrinsic positive transcription factors. However, it remains elusive how these two events are integrated to ensure appropriate neural conversion. Here, we show that Oct6 functions as an essential positive factor for neural differentiation of mouse embryonic stem cells (ESCs), specifically during the transition from epiblast stem cells (EpiSCs) to neural progenitor cells (NPCs). Chimera analysis showed that Oct6 knockdown leads to markedly decreased incorporation of ESC in neuroectoderm. By contrast, Oct6-overexpressing ESC derivatives preferentially contribute to neuroectoderm. Genome-wide ChIP-seq and RNA-seq analyses indicate that Oct6 is an upstream activator of neural lineage genes, and also a repressor of BMP and Wnt signalings. Our results establish Oct6 as a critical regulator that promotes neural commitment of pluripotent stem cells through a dual role: activating internal neural induction programs and antagonizing extrinsic neural inhibitory signals. RNA-seq was performed to examine Oct6 function in ESC neural differentiation at Day2, Day4 and Day6 after dox induction. On Day4 EB, ChIP-seq assay was ultilized to characterize the targets of Oct6.
Project description:Lipid metabolism is recognized as a key process for stem cell maintenance and differentiation but genetic factors that instruct stem cell function by influencing lipid metabolism remain to be delineated. Here we identify Tnfaip2 as an inhibitor of reprogramming of mouse fibroblasts into induced pluripotent stem cells. Tnfaip2 knockout embryonic stem cells (ESCs) exhibit differentiation failure and knockdown of the planarian orthologue, Smed-exoc3, abrogates in vivo differentiation of somatic stem cells, tissue homeostasis, and regeneration. Tnfaip2 deficient ESCs fail to induce synthesis of cellular triacylglycerol (TAG) and lipid droplets (LD) coinciding with reduced expression of Vimentin (Vim) – a known inducer of LD formation. Knockdown of Vim and Tnfaip2 act epistatically in enhancing cellular reprogramming of mouse fibroblasts. Similarly, planarians devoid of Smed-exoc3 displayed acute loss of TAGs. Supplementation of palmitic acid (PA) and palmitoyl-L-carnitine (a mitochondrial carrier of PA) restores the differentiation capacity of Tnfaip2 deficient ESCs as well as stem cell differentiation and organ maintenance in Smed-exoc3-depleted planarians. Together, these results identify a novel pathway, which is essential for stem cell differentiation and organ maintenance by instructing lipid metabolism.
Project description:Lipid metabolism is recognized as a key process for stem cell maintenance and differentiation but genetic factors that instruct stem cell function by influencing lipid metabolism remain to be delineated. Here we identify Tnfaip2 as an inhibitor of reprogramming of mouse fibroblasts into induced pluripotent stem cells. Tnfaip2 knockout embryonic stem cells (ESCs) exhibit differentiation failure and knockdown of the planarian orthologue, Smed-exoc3, abrogates in vivo differentiation of somatic stem cells, tissue homeostasis, and regeneration. Tnfaip2 deficient ESCs fail to induce synthesis of cellular triacylglycerol (TAG) and lipid droplets (LD) coinciding with reduced expression of Vimentin (Vim) – a known inducer of LD formation. Knockdown of Vim and Tnfaip2 act epistatically in enhancing cellular reprogramming of mouse fibroblasts. Similarly, planarians devoid of Smed-exoc3 displayed acute loss of TAGs. Supplementation of palmitic acid (PA) and palmitoyl-L-carnitine (a mitochondrial carrier of PA) restores the differentiation capacity of Tnfaip2 deficient ESCs as well as stem cell differentiation and organ maintenance in Smed-exoc3-depleted planarians. Together, these results identify a novel pathway, which is essential for stem cell differentiation and organ maintenance by instructing lipid metabolism.
Project description:The neural fate commitment of pluripotent stem cells requires repression of extrinsic inhibitory signals and activation of intrinsic positive transcription factors. However, it remains elusive how these two events are integrated to ensure appropriate neural conversion. Here, we show that Oct6 functions as an essential positive factor for neural differentiation of mouse embryonic stem cells (ESCs), specifically during the transition from epiblast stem cells (EpiSCs) to neural progenitor cells (NPCs). Chimera analysis showed that Oct6 knockdown leads to markedly decreased incorporation of ESC in neuroectoderm. By contrast, Oct6-overexpressing ESC derivatives preferentially contribute to neuroectoderm. Genome-wide ChIP-seq and RNA-seq analyses indicate that Oct6 is an upstream activator of neural lineage genes, and also a repressor of BMP and Wnt signalings. Our results establish Oct6 as a critical regulator that promotes neural commitment of pluripotent stem cells through a dual role: activating internal neural induction programs and antagonizing extrinsic neural inhibitory signals.
Project description:The use of pluripotent stem cells in regenerative medicine and disease modeling is complicated by the variation in differentiation properties between lines. In this study, we characterized 13 human embryonic stem cell. (hESC) and 26 human induced pluripotent stem cell (hiPSC) lines to identify markers that predict neural differentiation behavior. At a general level, markers previously known to distinguish mouse ESCs from epiblast stem cells (EpiSCs) correlated with neural differentiation behavior. More specifically, quantitative analysis of miR-371-3 expression prospectively identified hESC and hiPSC lines with differential neurogenic differentiation propensity and in vivo dopamine neuron engraftment potential. Transient KLF4 transduction increased miR-371-3 expression and altered neurogenic behavior and pluripotency marker expression. Conversely, suppression of miR- 371-3 expression in KLF4-transduced cells rescued neural differentiation propensity. miR-371-3 expression level therefore appears to have both a predictive and a functional role in determining human pluripotent stem cell neurogenic differentiation behavior.