Nucleosome occupancy changes in mammalian cell differentiation and reprogramming (microarray)
ABSTRACT: Embryonic stem cells (ESCs) and induced-pluripotent stem cells (iPSCs) self-renew and differentiate into an array of cell types in vitro and in vivo. A complex network of genetic and epigenetic pathways regulates the self-renewal and differentiation of these pluripotent cells, and the structure and covalent modifications of chromatin play a prominent role in this process. We examine nucleosome occupancy in mouse and human embryonic stem cells (ESCs), induced-pluripotent stem cells (iPSCs), and differentiated cell types using MNase-seq. To address variability inherent in this technique, we developed a bioinformatic approach that enabled the identification of regions of difference (RoD) in nucleosome occupancy between pluripotent and somatic cells. The majority of changes in nucleosomal signatures that occur in differentiation are reset during reprogramming. We conclude that changes in nucleosome occupancy are a hallmark of pluripotency and likely identify key regulatory regions that play a role in determining cell identity. A six chip study using total RNA recovered from three cell types with 2 replicates each
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:Variation in chromatin composition and organization often reflects differences in genome function. Histone variants, for example, replace canonical histones to contribute to regulation of numerous nuclear processes including transcription, DNA repair and chromosome segregation. Here we focus on H2A.Bbd, a rapidly evolving variant found in mammals but not in invertebrates. We report that in human cells, nucleosomes bearing H2A.Bbd form unconventional chromatin structures enriched within actively transcribed genes and characterized by shorter DNA protection and nucleosome spacing. Analysis of transcriptional profiles from cells depleted for H2A.Bbd demonstrated widespread changes in gene expression with a net down-regulation of transcription and disruption of normal mRNA splicing patterns. In particular, we observed changes in exon inclusion rates and increased presence of intronic sequences in mRNA products upon H2A.Bbd depletion. Taken together, our results indicate that H2A.Bbd is involved in formation of a specific chromatin structure that facilitates both transcription and initial mRNA processing. Gene expression was measured in two replicates of the HeLa cells expressing H2A.Bbd-FLAG histone, which were treated with shRNA with no homology to the human genome.
Project description:Investigation on expression levels of normal tissue from prostate cancer patients on locus 8q24. 3 chips with 3 arrays each study, using 3 pairs of normal vs. tumor tissue and 3 replicates of the same sample. Each chip contained one pair of normal vs. tumor and one copy of the repeated sample.
Project description:Investigation on expression levels of normal tissue from prostate cancer patients on locus 8q24. The region chr8:127640000-129120000 is tiled with 60 nt probes at 10 nt interval (hg18) 7 chip study, using 7 independent samples.
Project description:Investigation on expression levels of normal tissue from prostate cancer patients on locus 8q24. The region chr8:127640000-129120000 is tiled with isothermal probes (hg17) 7 chip study, using 7 independent samples.
Project description:RUNX2 is a transcription factor that is first expressed in early osteoblast-lineage cells and represents a primary determinant of osteoblastogenesis. While numerous target genes are regulated by RUNX2, little is known of sites on the genome occupied by RUNX2 or of the gene networks that are controlled by these sites. To explore this, we conducted a genome-wide analysis of the RUNX2 cistrome in both pre-osteoblastic MC3T3-E1 cells (POB) and their mature osteoblast progeny (OB), characterized the two cistromes and assessed their relationship to changes in gene expression. We found that although RUNX2 was widely bound to the genome in POB cells, this binding profile was reduced upon differentiation to OBs. Numerous sites were lost upon differentiation, new sites were also gained; many sites remained common to both cell states. Additional features were identified as well including location relative to potential target genes, abundance with respect to single genes, the frequent presence of a consensus TGTGGT RUNX2 binding motif, co-occupancy by C/EBPβ and the presence of a typical epigenetic histone enhancer signature. This signature was changed quantitatively following differentiation. While RUNX2 binding sites were associated extensively with adjacent genes, the distal nature of the majority of these sites prevented assessment of whether they represented direct targets of RUNX2 action. Changes in gene expression, however, revealed an abundance of genes that contained RUNX2 binding sites and were regulated in concert. These studies establish a basis for further analysis of the role of RUNX2 activity and its function during osteoblast lineage maturation. RNA was isolated and applied to gene expression microarrays in undifferentiated MC3T3-E1 cells as well as post 15 day osteogenic differentiation MC3T3-E1 cells. The samples were completed in biological triplicate.
Project description:The biological effects of 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) on osteoblast differentiation and function differ significantly depending upon the cellular state of maturation. To explore this phenomenon mechanistically, we examined the impact of 1,25(OH)2D3 on the transcriptomes of both pre-osteoblastic (POBs) and differentiated osteoblastic (OBs) MC3T3-E1 cells, and assessed localization of the vitamin D receptor (VDR) at sites of action on a genome-scale using ChIP-seq analysis. We observed that the 1,25(OH)2D3-induced transcriptomes of POBs and OBs were quantitatively and qualitatively different, supporting not only the altered biology observed but the potential for a change in VDR interaction at the genome as well. This idea was confirmed through discovery that VDR cistromes in POBs and OBs were also strikingly different. Depletion of VDR binding sites in OBs, due in part to reduced VDR expression, was the likely cause of the loss of VDR-target gene interaction. Continued novel regulation by 1,25(OH)2D3, however, suggested that factors in addition to the VDR might also be involved. Accordingly, we show that transcriptomic modifications are also accompanied by changes in genome binding of the master osteoblast regulator RUNX2 and the chromatin remodeler C/EBPβ. Importantly, genome occupancy was also highlighted by the presence of epigenetic enhancer signatures which were selectively changed in response to both differentiation and 1,25(OH)2D3. The impact of VDR, RUNX2, and C/EBPβ on osteoblast differentiation is exemplified by their actions at the Runx2 and Sp7 gene loci. We conclude that each of these mechanisms may contribute to the diverse actions of 1,25(OH)2D3 on differentiating osteoblasts. RNA was isolated and applied to gene expression microarrays in undifferentiated MC3T3-E1 cells as well as post 15 day osteogenic differentiation MC3T3-E1 cells, which were treated for 24 hours with 10-7M 1,25(OH)2D3. For the vehicle matched samples, please refer to study GSE41955. The samples were completed in biological triplicate.
Project description:Investigation of whole genome gene expression level changes of LncRNAs in tumor tissues and paired non-tumor tissues in HBV-positive hapatocellular carcinoma. The different expression genes were further analysised. The human LncRNA microarray analysis of the 10 samples (5 non-tumor tissues and 5 paired tumor tissues) were completed. Total RNA from each sample was quantified using the NanoDrop ND-1000 and RNA integrity was assessed using standard denaturing agarose gel electrophoresis. Total RNA of each sample was used for labeling and array hybridization as the following steps: 1) Reverse transcription with by Invitrogen Superscript ds-cDNA synthesis kit; 2) ds-cDNA labeling with NimbleGen one-color DNA labeling kit; 3) Array hybridization using the NimbleGen Hybridization System and followed by washing with the NimbleGen wash buffer kit; 4) Array scanning using the Agilent Scanner G2505C. Scanned images (TIFF format) were then imported into NimbleScan software (version 2.5) for grid alignment and expression data analysis. Expression data were normalized through quantile normalization and the Robust Multichip Average (RMA) algorithm included in the NimbleScan software. The Probe level (*_norm_RMA.pair) files and mRNA level (*_RMA.calls) files were generated after normalization. All mRNAs level files were imported into Agilent GeneSpring GX software (version 11.5.1) for further analysis.mRNAs that at least 3 out of 6 samples have values greater than or equal to lower cut-off: 50.0 (“All Targets Value”) were chosen for further data analysis. Differentially expressed mRNAs were identified through Volcano Plot filtering. Pathway analysis and GO analysis were applied to determine the roles of these differentially expressed mRNAs played in these biological pathways or GO terms. Finally, Hierarchical Clustering was performed to show the distinguishable mRNAs expression pattern among samples.
Project description:A significant percentage of HIV-infected individuals experience a sharp decline in CD4+ T cell counts and progress to AIDS quickly after primary infection. Identification of biomarkers distinguishing rapid progressors (RPs) versus chronic progressors (CPs) is critical for early clinical intervention and could provide novel strategies to facilitate vaccine design and immune therapy. mRNA and miRNA expression profiles in the peripheral blood mononuclear cells (PBMCs) of RPs and CPs were investigated at 111±22 days (Mean±SD) of HIV infection. The association of mRNA and miRNA expression with disease progression was examined by receiver operating characteristic analysis and Kaplan-Meier survival analysis. Pathway enrichment analysis showed that genes with deregulated expression in RPs are primarily involved in apoptosis pathways. Furthermore, we found that 5 miRNAs (miR-31, -200c, -526a, -99a and -503) in RPs were significantly decreased compared to those in CPs (P<0.05). The decreased expression of these miRNAs was associated with rapid disease progression of HIV infection with a 94% predictive value as measured by the area under the curve. The upregulated predicted targets from the 5 signature miRNAs and all upregulated genes identified from mRNA microarray converged to the apoptosis pathway. Moreover, overexpression of miR-31 in primary human T cells promoted their survival. Our results have identified a distinct transcriptomic signature in PBMCs of RPs and provided novel insights to the pathogenesis of HIV infection. A cohort of primary HIV infected individuals with different disease outcome were enrolled in this study. We included 6 individuals with rapid disease progression (RP), seven with chronic disease progression (CP). The HIV infected individuals were never on therapy before the time of sample taken.