Cellular reprogramming converts differentiated cells into induced pluripotent stem cells (iPSCs). However, this process is extremely inefficient, complicating mechanistic studies. Here, we identified and molecularly characterized rare, early intermediates poised to reprogram with up to 100% efficiency, without perturbing additional genes or pathways. Analysis of these cells uncovered transcription factors (e.g., Tfap2c, Bex2), which are critical for reprogramming but dispensable for pluripotency maintenance. Additionally, we observed striking patterns of chromatin hyperaccessibility at pluripotency loci, which preceded gene expression in poised intermediates. Finally, inspection of these hyperaccessible regions revealed a previously unappreciated early wave of DNA demethylation, which is uncoupled from de novo methylation of somatic regions late in reprogramming. Overall, our study underscores the importance of investigating the rare intermediates poised to produce iPSCs, provides novel insights into the mechanisms of reprogramming, and offers a valuable resource for the dissection of transcriptional and epigenetic dynamics intrinsic to cell fate change. Overall design: RNA-seq of reprogramming intermediates (11 cell types in triplicate).
Prospective Isolation of Poised iPSC Intermediates Reveals Principles of Cellular Reprogramming.
Specimen part, Cell line, Subject
View SamplesCellular reprogramming converts differentiated cells into induced pluripotent stem cells (iPSCs). However, this process is extremely inefficient, complicating mechanistic studies. Here, we identified and molecularly characterized rare, early intermediates poised to reprogram with up to 100% efficiency, without perturbing additional genes or pathways. Analysis of these cells uncovered transcription factors (e.g., Tfap2c, Bex2), which are critical for reprogramming but dispensable for pluripotency maintenance. Additionally, we observed striking patterns of chromatin hyperaccessibility at pluripotency loci, which preceded gene expression in poised intermediates. Finally, inspection of these hyperaccessible regions revealed a previously unappreciated early wave of DNA demethylation, which is uncoupled from de novo methylation of somatic regions late in reprogramming. Overall, our study underscores the importance of investigating the rare intermediates poised to produce iPSCs, provides novel insights into the mechanisms of reprogramming, and offers a valuable resource for the dissection of transcriptional and epigenetic dynamics intrinsic to cell fate change. Overall design: RNA-seq of reprogramming intermediates (6 cell types in duplicate).
Prospective Isolation of Poised iPSC Intermediates Reveals Principles of Cellular Reprogramming.
Specimen part, Cell line, Subject
View SamplesHere we identify a Dicer-independent miRNA biogenesis pathway that employs the slicer catalytic activity of Argonaute2 (Ago2). To uncover Dicer-independent miRNAs, we sequenced small RNAs in wild type, maternal-zygotic dicer (MZdicer) and MZago2 mutants, using zebrafish as a model system. We find that, in contrast to other miRNAs, miR-451 levels were increased in MZdicer but drastically reduced in the MZago2 mutants. We show that pre-miR-451 processing requires Ago2 catalytic activity in vivo. MZago2 mutant embryos display delayed erythrocyte maturation that can be rescued by wild type Ago2 or miR-451 duplex but not catalytically dead Ago2. We propose that Ago2-mediated cleavage of a subset of pre-miRNAs, followed by uridylation and trimming, generates functional miRNAs in a Dicer-independent manner. Overall design: Examination of small RNAs (18 to 35 nucleotides) in 3 different zebrafish genotypes (wild type, MZago2, MZdicer) at 48 hours post-fertilization.
A novel miRNA processing pathway independent of Dicer requires Argonaute2 catalytic activity.
No sample metadata fields
View SamplesThe generation of induced pluripotent stem cells (iPSCs) from differentiated cells following forced expression of Oct4, Klf4, Sox2 and c-Myc (OKSM) is slow and inefficient, suggesting that transcription factors have to overcome somatic barriers that resist cell fate change. Here, we performed an ubiased serial shRNA enrichment screen to identify novel repressors of somatic cell reprogramming into iPSCs. This effort uncovered the sumoylation effector protein Sumo2 as one of the strongest roadblocks to iPSC formation. Depletion of Sumo2 both enhances and accelerates reprogramming, yielding transgene-independent, chimera-competent iPSCs after as little as 36 hours of OKSM expression. We further show that the Sumo2 pathway acts independently of exogenous c-Myc expression and in parallel with small molecule enhancers of reprogramming. Critically, suppression of SUMO2 also promotes the generation of human iPSCs. Together, our results reveal sumoylation as a crucial post-transcriptional mechanism that resists the acquisition of pluripotency from fibroblasts using defined factors.
A Serial shRNA Screen for Roadblocks to Reprogramming Identifies the Protein Modifier SUMO2.
Sex, Specimen part, Time
View SamplesTo understand the underlying mechanism by which Alox15 gene is required by HSCs, we performed a comparative DNA microarray analysis using total RNA isolated from wild type Lin-Sca-1+c-Kit+, SELP-/- Lin-Sca-1+c-Kit+. The result was validated by quantitative real-time PCR analysis of wild type Lin-Sca-1+c-Kit+ and SELP-/- Lin-Sca-1+c-Kit+.
Arachidonate 15-lipoxygenase is required for chronic myeloid leukemia stem cell survival.
No sample metadata fields
View SamplesThis SuperSeries is composed of the SubSeries listed below.
A molecular roadmap of reprogramming somatic cells into iPS cells.
Specimen part, Time
View SamplesFactor induced reprogramming is a slow and inefficient process with only rare cells progressing towards induced pluripotent stem cells (iPSCs). Owing to these restraints, mechanistic studies have been limited to analyses of heterogeneous bulk populations undergoing reprogramming and partially reprogrammed cell lines. Here, by combining surface markers (Thy1, SSEA1) and an Oct4-GFP fluorescent reporter allele, we analyzed defined intermediate cell populations poised to becoming iPSCs at the transcriptional and epigenetic levels using genome-wide and single cell technologies. We found that factor-induced reprogramming elicits two discernible transcriptional waves that are characterized by the initial extinction of the somatic gene expression program and the concomitant acquisition of an ESC-like proliferative and metabolic state, followed by the activation of an embryonic pluripotent state primed for differentiation. The first wave is mostly driven by gene activation through c-Myc and gene repression by Klf4, whereas the second wave is a result of gradually activated Oct4/Sox2 targets in cooperation with Klf4 targets and other downstream regulators. While microRNA expression and enrichment for individual histone modifications (H3K4me3 or H3K27me3 enriched promoters) mirrored the observed biphasic transcriptional pattern, the establishment of bivalent domains (H3K4me3/H3K27me3 enriched promoters) occurred more gradually. In contrast, changes in DNA methylation took place predominantly at the end of reprogramming when cells assumed a stable pluripotent state. Cells that became refractory to reprogramming activated the first but failed to initiate the second transcriptional wave. However, introduction of additional copies of the reprogramming transgenes into these cells rescued their ability to form iPSCs, indicating that suboptimal transcription factor levels are a limiting factor for efficient iPSC formation. This integrative analysis allowed us to identify novel genes and microRNAs that enhance reprogramming and surface markers that further subdivide intermediate cell populations. Collectively, our data offer new mechanistic insights into the nature and sequence of molecular events inherent to cellular reprogramming and provide a valuable resource of molecules that may act as roadblocks during iPSC formation.
A molecular roadmap of reprogramming somatic cells into iPS cells.
No sample metadata fields
View SamplesMacrophages in tumor microenvironment have been characterized as M1- and M2-polarized subtypes. This study sought to investigate the effects of different macrophage subtypes on the biological behavior and global gene expression profiles of lung cancer cells. Expression microarray and bioinformatics analyses indicated that the different macrophage subtypes mainly regulated genes involved in cell cycle, cytoskeletal remodeling, coagulation, cell adhesion and apoptosis pathways in A549 cells, a pattern that correlated with the altered behavior of A549 cells observed after coculture with macrophage subtypes.
Opposite Effects of M1 and M2 Macrophage Subtypes on Lung Cancer Progression.
Specimen part, Cell line
View SamplesIn order to identify patterns of gene expression associated with biological effects in THP-1 cells induced by F3, we performed a transcriptomic analysis on the THP-1 control and F3-treated THP-1 cells by oligonucleotide microarray
Ganoderma lucidum polysaccharides in human monocytic leukemia cells: from gene expression to network construction.
Cell line
View SamplesThe CLS1/CAF co-culture maintained the cancer stemness. This cancer stemness was lost when the CAF feeder cells were removed during passaging.
Cancer-associated fibroblasts regulate the plasticity of lung cancer stemness via paracrine signalling.
Cell line
View Samples