Wnt signaling is intrinsic to mouse embryonic stem cell self-renewal. Therefore it is surprising that reprogramming of somatic cells to induced pluripotent stem cells (iPSCs) is not strongly enhanced by Wnt signaling. Here, we demonstrate that active Wnt signaling inhibits the early stage of reprogramming to iPSCs, while it is required and even stimulating during the late stage. Mechanistically, this biphasic effect of Wnt signaling is accompanied by a change in the requirement of all four of its transcriptional effectors: Tcf1, Lef1, Tcf3, and Tcf4. For example, Tcf3 and Tcf4 are stimulatory early but inhibitory late in the reprogramming process. Accordingly, ectopic expression of Tcf3 early in reprogramming combined with its loss-of-function late enables efficient reprogramming in the absence of ectopic Sox2. Together, our data indicate that the step-wise process of reprogramming to iPSCs is critically dependent on the stage-specific control and action of all four Tcfs and Wnt signaling.
Stage-specific regulation of reprogramming to induced pluripotent stem cells by Wnt signaling and T cell factor proteins.
Specimen part, Time
View SamplesDetailed analysis comparing hiPSC lines that were newly generated and compared them to already established hiPSC lines
Molecular analyses of human induced pluripotent stem cells and embryonic stem cells.
Specimen part, Cell line
View SamplesIn order to recover nuclei with two active X chromosomes (class I), we developed a reprogramming strategy by supplementing hESC media with the small molecules sodium butyrate, and 3-deazaneplanocin A (DZNep). In order to determine how B+D affects global gene expression, we performed microarray analysis in triplicate in the HSF-6 (8) C and HSF-6 (8) B+D treated cultures. We also evaluated HSF-6 (S9) B+D in triplicate and identified no statistically significant changes in gene expression in HSF-6 (S9) B+D compared to HSF-6 (8) B+D treated cultures. This suggests that global transcriptional differences are more strongly modulated by presence or absence of B+D and not the percentage of class I, II or III nuclei.
Derivation of new human embryonic stem cell lines reveals rapid epigenetic progression in vitro that can be prevented by chemical modification of chromatin.
Cell line
View SamplesInduced pluripotent stem (iPS) cells can be obtained from fibroblasts by expression of Oct4, Sox2, Klf4, and c-Myc. To determine how these factors induce this change in cell identity, we carried out genomewide promoter analysis of their binding in iPS and partially reprogrammed cells. Most targets in iPS cells are shared with ES cells and the factors cooperate to activate the ES-like expression program. In partially reprogrammed cells, genes bound by c-Myc have achieved a more ES-like binding and expression pattern. In contrast, genes that are co-bound by Oct4, Sox2, and Klf4 in ES cells and that encode pluripotency regulators show severe lack of both binding and transcriptional activation. Among the factors, c-Myc has a pivotal effect on the initiation of the ES transcription program, including the repression of fibroblast-specific genes. Our analysis begins to unravel how the four factors function together and suggests a temporal and separable order of their effects during reprogramming.
Role of the murine reprogramming factors in the induction of pluripotency.
No sample metadata fields
View SamplesOct4, Sox2, Klf4, and cMyc (OSKM) reprogram somatic cells to pluripotency. To gain a mechanistic understanding of their function, we mapped OSKM-binding, stage-specific transcription-factors (TFs), and chromatin-states in discrete reprogramming stages and performed loss- and gain-of-function experiments. We found that early in reprogramming OSK extensively bind somatic-enhancers and initiate their decommissioning by recruiting Hdac1. Concurrently, OSK engage other sites, including specific pluripotency-enhancers, and induce the relocation of somatic TFs to these sites and away from somatic-enhancers, extending somatic-enhancer decommissioning genome-wide. Pluripotency-enhancer selection early in reprogramming occurs predominantly at sites with high OSK-motif densities and requires collaborative binding by OSK. Most pluripotency-enhancers are selected later and occupied by OS and stage-specific-TFs like Esrrb. Overexpression of stage-specific-TFs influences reprogramming efficiency by changing OSK-occupancy, somatic-enhancer decommissioning, and pluripotency-enhancer selection. We propose that collaborative interactions among OSK and with stage-specific-TFs direct both somatic-enhancer decommissioning and pluripotency-enhancer selection, which drives the enhancer reorganization underlying reprogramming Overall design: RNA-seq
Cooperative Binding of Transcription Factors Orchestrates Reprogramming.
Specimen part, Cell line, Subject
View SamplesExpression profile of dermal fibroblasts reprogrammed to a pluripotent state
Generation of human induced pluripotent stem cells from dermal fibroblasts.
No sample metadata fields
View SamplesThe balance between glycolytic and oxidative metabolism shifts during differentiation of human embryonic stem cells (hESCs) and during reprogramming of somatic cells into pluripotent stem cells. However the contribution of glycolytic metabolism to various stages of pluripotency is not well understood. Additionally, few tools have been developed that modulate pluripotent stem cell glycolytic metabolism to influence self-renewal or differentiation. Here we show that the degree of human pluripotency is associated with glycolytic rate, whereby naive hESCs exhibit higher glycolytic flux, increased MYC transcriptional activity, and elevated nuclear N-MYC levels relative to primed hESCs. Consistently, the inner cell mass of human blastocysts also exhibits increased MYC transcriptional activity relative to primed hESCs and elevated nuclear N-MYC levels. Expression of the lactate transporter, monocarboxylate transporter 1 (MCT1), is strongly associated with the pluripotent state, and reduction of glycolysis using a small molecule inhibitor towards MCT1 decreases self-renewal of nave hESCs and feeder-free cultured primed hESCs, but not that of primed hESCs grown in feeder-supported conditions. Lastly, reduction of glycolytic metabolism via MCT1 inhibition in feeder-free primed hESCs enhances neural lineage specification. These findings validate the association between glycolytic metabolism and pluripotency, reveal differences in the glucose metabolism of feeder- versus feeder-free cultured hESCs, and show that pharmacologic regulation of glycolysis can influence self-renewal and initial cell fate specification of human pluripotent stem cells.
Glycolytic Metabolism Plays a Functional Role in Regulating Human Pluripotent Stem Cell State.
Cell line, Treatment
View SamplesDue to their somatic cell origin, human induced pluripotent stem cells (HiPSCs) are assumed to carry a normal diploid genome, and adaptive chromosomal aberrations have not been fully evaluated. Here, we analyzed the chromosomal integrity of 66 HiPSC and 38 human embryonic stem cell (HESC) samples from 18 different studies by global gene expression meta-analysis. We report identification of a substantial number of cell lines carrying full and partial chromosomal aberrations, half of which were validated at the DNA level. Several aberrations resulted from culture adaptation, and others are suspected to originate from the parent somatic cell. Our classification revealed a third type of aneuploidy already evident in early passage HiPSCs, suggesting considerable selective pressure during the reprogramming process. The analysis indicated high incidence of chromosome 12 duplications, resulting in significant enrichment for cell cycle related genes. Such aneuploidy may limit the differentiation capacity and increase the tumorigenicity of HiPSCs.
Identification and classification of chromosomal aberrations in human induced pluripotent stem cells.
Specimen part, Cell line
View SamplesDue to their somatic cell origin, human induced pluripotent stem cells (HiPSCs) are assumed to carry a normal diploid genome, and adaptive chromosomal aberrations have not been fully evaluated. Here, we analyzed the chromosomal integrity of 66 HiPSC and 38 human embryonic stem cell (HESC) samples from 18 different studies by global gene expression meta-analysis. We report identification of a substantial number of cell lines carrying full and partial chromosomal aberrations, half of which were validated at the DNA level. Several aberrations resulted from culture adaptation, and others are suspected to originate from the parent somatic cell. Our classification revealed a third type of aneuploidy already evident in early passage HiPSCs, suggesting considerable selective pressure during the reprogramming process. The analysis indicated high incidence of chromosome 12 duplications, resulting in significant enrichment for cell cycle related genes. Such aneuploidy may limit the differentiation capacity and increase the tumorigenicity of HiPSCs.
Identification and classification of chromosomal aberrations in human induced pluripotent stem cells.
Specimen part, Cell line
View SamplesDue to their somatic cell origin, human induced pluripotent stem cells (HiPSCs) are assumed to carry a normal diploid genome, and adaptive chromosomal aberrations have not been fully evaluated. Here, we analyzed the chromosomal integrity of 66 HiPSC and 38 human embryonic stem cell (HESC) samples from 18 different studies by global gene expression meta-analysis. We report identification of a substantial number of cell lines carrying full and partial chromosomal aberrations, half of which were validated at the DNA level. Several aberrations resulted from culture adaptation, and others are suspected to originate from the parent somatic cell. Our classification revealed a third type of aneuploidy already evident in early passage HiPSCs, suggesting considerable selective pressure during the reprogramming process. The analysis indicated high incidence of chromosome 12 duplications, resulting in significant enrichment for cell cycle related genes. Such aneuploidy may limit the differentiation capacity and increase the tumorigenicity of HiPSCs.
Identification and classification of chromosomal aberrations in human induced pluripotent stem cells.
Specimen part, Cell line
View Samples