Project description:Mouse B cells, upon ectopic expression of the transcription factor C/EBPalpha for 18h, can be reprogrammed to induced pluripotent stem (iPS) cells with extremely high efficiency. To understand the molecular control of this phenomenon we performed a time course proteomic analysis by label-free protein quantification of proteins during B cell reprogramming to iPS cells.
Project description:E-cadherin upregulation is an early event of reprogramming of fibroblasts to induce pluripotent stem cells (iPS). Knocking down of E-cadherin by shRNA impairs iPS generation, though some colonies with great morphorlogical difference to shRNA control colonies remain. To illustrate the molecular and functional difference between shECAD iPS clones and shRNA control iPS clones, three respective iPS clones (shECAD 4,8,9 and Ctrl 2,3,4) were derived and DNA microarrays were run to analyze the transcriptional profile of these clones.
Project description:Investigation of whole genome gene expression level changes in neural progenitor cells derived from iPS cells generated from umbilical cord mesenchymal cells, compared to neural progenitor cells derived from iPS cells generated fromskin fibroblasts. Analyze the difference between neural progenitor cells derived from iPS cells generated from different origins. The method to induce reprogramming of somatic cells and human iPS cells for neural differentiation is described in Cai J, Li W, Su H, Qin D, Yang J, et al. (2010) Generation of human induced pluripotent stem cells from umbilical cord matrix and amniotic membrane mesenchymal cells. J Biol Chem 285: 11227-11234. and Kim DS, Lee JS, Leem JW, Huh YJ, Kim JY, et al. (2010) Robust enhancement of neural differentiation from human ES and iPS cells regardless of their innate difference in differentiation propensity. Stem Cell Rev 6: 270-281.
Project description:We tested a genome-scale artificial transcription factor (ATF) library in reprogramming mouse embryonic fibroblasts to induced pluripotent stem (iPS) cells. Three combinations of ATFs (C2, C3, and C4) could induce pluripotency when expressed with Sox2, Klf4, and c-Myc. The transcriptional profiles of ATF-induced iPS cells are similar to that of iPS cells induced with Oct4, Sox2, Klf4, and c-Myc and mouse embryonic stem cells, exhibiting up-regulation of pluripotency markers and down-regulation of fibroblast markers. We performed ChIP-seq on the active histone mark H3K27ac and the repressive histone mark H3K9me3 in C2+SKM iPS cells, C3+SKM iPS cells, in Oct4+SKM to validate the total transcriptome results. In addition, the ATFs from C2 were chromatin immunoprecipitated to determine where they are bound in the genome at an intermediate stage before being fully reprogrammed to iPS cells. This study provides a proof-of-principle that a gene-activating ATF library can be used to identify cell fate-defining transcriptional networks in an unbiased manner.
Project description:Investigation of whole genome gene expression level changes in neural progenitor cells derived from iPS cells generated from umbilical cord mesenchymal cells, compared to neural progenitor cells derived from iPS cells generated fromskin fibroblasts. Analyze the difference between neural progenitor cells derived from iPS cells generated from different origins. The method to induce reprogramming of somatic cells and human iPS cells for neural differentiation is described in Cai J, Li W, Su H, Qin D, Yang J, et al. (2010) Generation of human induced pluripotent stem cells from umbilical cord matrix and amniotic membrane mesenchymal cells. J Biol Chem 285: 11227-11234. and Kim DS, Lee JS, Leem JW, Huh YJ, Kim JY, et al. (2010) Robust enhancement of neural differentiation from human ES and iPS cells regardless of their innate difference in differentiation propensity. Stem Cell Rev 6: 270-281. A two-chip study using total RNA recovered from one neural progenitor cell line derived from iPS cells generated from skin fibroblasts (GZF1C7NSCP3) and one neural progenitor cell line derived from iPS cells generated from umbilical cord mesenchymal cells (VMC2C7NSCP3). No replicates were made. Each chip measures the expression level of 45,033 genes from the two samples with fourteen 60-mer probe pairs (PM/MM) per gene, with three-fold technical redundancy.
Project description:The ability to induce pluripotent stem cells from committed, somatic human cells provides tremendous potential for regenerative medicine. However, there is a defined neoplastic potential inherent to such reprogramming that must be understood and may provide a model for understanding key events in tumorigenesis. Using genome-wide assays, we identify cancer-related epigenetic abnormalities that arise early during reprogramming and persist in induced pluripotent stem cell (iPS) clones. These include hundreds of abnormal gene silencing events, patterns of aberrant responses to epigenetic-modifying drugs resembling those for cancer cells, and presence in iPS and partially reprogrammed cells of cancer-specific gene promoter DNA methylation alterations. Our findings suggest that by studying the process of induced reprogramming, we may gain significant insight into the origins of epigenetic gene silencing associated with human tumorigenesis, and add to means of assessing iPS for safety. Direct expression comparison of iPS lines, cultured stem cell lines and normal differentiated cells. Re-expression experiments with 5-aza-2′-deoxycytidine (AZA) and trichostatin A (TSA) to identify hypermethylated genes.
Project description:Differentiated cells can be reprogrammed to an embryonic-like state by transfer of their nuclear contents into oocytes or by fusion with embryonic stem (ES) cells. Little is known about the factors that induce this reprogramming. Here we show that the combination of four factors, Oct3/4, Sox2, c-Myc, and Klf4, can generate pluripotent-like stem cells directly from mouse embryonic or adult fibroblast cultures. Unexpectedly, Nanog was dispensable in this process. These cells, which we designated iPS (induced pluriopotent-like stem) cells, exhibit the morphology and growth properties of ES cells and express ES cell marker genes. Subcutaneous transplantation of iPS cells into nude mice resulted in tumors containing a variety of tissues from all three germ layers. Following injection into blastocysts, iPS cells contributed to mouse embryonic development. These data demonstrate that pluripotent-like cells can be directly generated from fibroblast cultures by the addition of only a few defined factors. Keywords: cell type comparison
Project description:The expression of four transcription factors (OCT3/4, SOX2, KLF4, and c-MYC) can reprogram mouse as well as human somatic cells to induced pluripotent stem (iPS) cells. Expression of the c-MYC, also known as an oncogene, might induce carcinogenesis and thus, iPS cells produced with the use of c-MYC transduction cannot be used for human therapeutic applications. Furthermore, reprogramming efficiency was significantly reduced in the absence of c-MYC transduction. Here, we generated iPS cells from mesenchymal stromal cells (MSCs) derived from human third molars (wisdom teeth) by retroviral transduction of OCT3/4, SOX2, and KLF4 without c-MYC. Interestingly, clonally expanded MSCs, named 10F-15, could be used for iPS cell generation with 100-fold higher efficiency compared to that of other clonally expanded MSCs and human dermal fibroblasts. These iPS cells resembled human embryonic stem (ES) cells in many aspects, including morphology, ES markers expression, global gene expression, epigenetic states, and the ability to differentiate into the three germ layers in vitro and in vivo. Because human third molars are discarded as clinical waste, our data indicate that MSCs isolated from human third molars are a valuable cell source for the generation of iPS cells.
Project description:Knowledge of both the global chromatin structure and the gene expression programs of human embryonic stem (ES) cells and induced pluripotent stem (iPS) cells should provide a robust means to assess whether the genomes of these cells have similar pluripotent states. Recent studies have suggested that ES and iPS cells represent different pluripotent states with substantially different gene expression profiles. We describe here a comparison of global chromatin structure and gene expression data for a panel of human ES and iPS cells. Genome-wide maps of nucleosomes with histone H3K4me3 and H3K27me3 modifications indicate that there is little difference between ES and iPS cells with respect to these marks. Gene expression profiles confirm that the transcriptional programs of ES and iPS cells show very few consistent differences. Although some variation in chromatin structure and gene expression was observed in these cell lines, these variations did not serve to distinguish ES from iPS cells. Examination of two histone modifications (H3K4me3 and H3K27me3) in 6 human ES cell lines, 8 human iPS cell lines, and 1 fibroblast cell line.