Project description:Tagged versions of thyroid hormone receptors alpha (TRa) and beta (TRb) were stably transfected in two C17.2 cell lines, C17.2a and C17.2b, respectively. We performed an affinity-based purification of chromatin (ChAP), and high-throughput sequencing was used to assess binding sites of both receptors (ChAP-Seq). Standard ChIP-Seq for RXR was also performed in C17.2a cells. These data allow us to compare binding sites for both receptors and to conclude that they were only partially redundant, with co-existence of receptor-specific sites. Examination of binding sites of the two thyroid hormone receptors (alpha, beta) in two cell lines (C17.2a, C17.2b), each expressing one of the receptors. Examination of RXR binding sites in C17.2a cells.
Project description:Metastatic (as well as tumor) microenvironments contain both cancer-promoting as well as cancer restraining factors. The balance between these opposing forces determines the fate of cancer cells that disseminate to secondary organ sites. In search for microenvironmental drivers or inhibitors of metastasis, we identified, in a previous study, the beta subunit of hemoglobin (HBB) as a lung-derived antimetastatic factor. In the present study, exploring mechanisms leading to melanoma brain metastasis, we discovered that brain-derived factors restrain proliferation and induce apoptosis and necrosis of brain-metastasizing melanoma cells. Employing various purification procedures, we identified a heterodimer composed of hemoglobin alpha and beta chains that performs these anti-metastatic functions. Neither the alpha nor the beta subunit alone were inhibitory. An alpha/beta chain dimer chemically purified from human hemoglobin inhibited the cell viability of primary melanomas, melanoma brain metastasis (MBM), and breast cancer cell lines. The dimer-induced DNA damage, cell cycle arrest at the SubG1 phase, apoptosis, and significant necrosis in four MBM cell lines. Proteomic analysis of dimer-treated MBM cells revealed that the dimer downregulates the expression of BRD4, GAB2, and IRS2 proteins playing crucial roles in cancer cell sustainability and progression.
Project description:Tagged versions of thyroid hormone receptors alpha (TRa) and beta (TRb) were stably transfected in two C17.2 cell lines, C17.2a and C17.2b, respectively. We performed an affinity-based purification of chromatin (ChAP), and high-throughput sequencing was used to assess binding sites of both receptors (ChAP-Seq). Standard ChIP-Seq for RXR was also performed in C17.2a cells. These data allow us to compare binding sites for both receptors and to conclude that they were only partially redundant, with co-existence of receptor-specific sites.
Project description:To identify the direct target genes of PPD2, tandem chromatin affinity purification (TChAP, Verkest et al. (2014)), a variant of chromatin immunoprecipitation (ChIP) in which tandem affinity tags are used instead of epitope tags, followed by sequencing (TChAP-Seq) was performed. An Arabidopsis cell suspension culture overexpressing an HBH-tagged PPD2 was used for the purification of the chromatin bound by PPD2.
Project description:color swap ratio profiles (dye-reversal) wildtype CD4+ alpha beta T cells vs. LATY136F CD4+ alpha beta T cells: GSM42565 and GSM42566 Keywords: repeat sample
Project description:Rodent models are widely used to study diabetes. Yet, significant gaps remain in our understanding of mouse islet physiology that reduce their accuracy as a model for human islet disease. We generated comprehensive transcriptomes of mouse beta and alpha cells using a novel bitransgenic mouse model generated for this purpose. This enables systematic comparison across thousands of genes between the two major endocrine cell types of the islets of Langerhans whose principal hormones are of cardinal importance for glucose homeostasis. Our data leveraged against similar data for human beta cells reveal a core common beta cell transcriptome of 9900+ genes and marked differences in the repertoire of receptors and long non-coding RNAs between mouse and human beta cells. The comprehensive comparison of the (dis)similarities between mouse and human beta cells represents an invaluable resource to boost the effectiveness by which rodent models offer guidance in finding cures for human diabetes. FACS purified alpha and beta cells from the same islets. Islets were isolated from bitransgenic offspring of a cross between mIns1-H2b-mCherry and S100b-eGFP transgenic reporter mice that mark beta and alpha cells, respectively. Islets from two replicate groups of 10 or 11 animals were pooled by sex to obtain sufficient material. Pooled islets were dissociated, sorted and collect in Trizol for RNA isolation and library construction.
Project description:MicroRNAs (miRNAs) are non-coding RNAs that play a fundamental role in regulation of gene expression affecting differentiation and development. In particular, miRNAs have been described to regulate genes important for pancreatic development and islet function. The aim of this work was to determine the miRNA expression signature in human pancreatic alpha and beta cells. miRNA stability to fixation allowed the study of microRNA in pure populations of human alpha and beta cells sorted by FACS after intracellular staining with glucagon and insulin, respectively. The determination of the specific group of miRNAs expressed in the human pancreatic alpha and beta cells may further the understanding of gene expression regulation of the islet differentiation process. The alpha and beta cells come from 6 different preparations of human pancreatic islets from donors. In this study we define expression profiles of a total of 665 miRNAs for pancreatic alpha and beta cells. For this purpose, cells were fixed with paraformaldehyde, 7AAD was applied to exclude dead cells. Then, cells were sorted after intracellular staining with C peptide to detect beta cells and glucagon to detect alpha cells. After sorting, we confirmed enriched beta cells have a purity of on average over 98%. Enriched alpha cells have a purity of on average over 98%. To determine the miRNA expression profiles, we used human miRNA TLDAs version 2. For each sample card A and card B were run after cDNA synthesis and 12 cycles of preamplification according to the manufacturer protocol. Each TLDA card A contains 1 probe for the endogenous control RNU48 while each TLDA card B contains 4 replicates of the RNU48 probe. Analysis of these controls allows calculating the intra- and inter-assay variation. Quantitative values (RQ) were calculated measuring the ddCt between the Ct values of each miRNA and the Ct value of the small nucleolar RNU48 RNA comparing the target sample and the control sample.
Project description:Insulin-secreting β cells and glucagon-secreting α cells maintain physiological blood glucose levels, and their malfunction drives diabetes development. Using ChIP sequencing and RNA sequencing analysis, we determined the epigenetic and transcriptional landscape of human pancreatic α, β, and exocrine cells. We found that, compared with exocrine and β cells, differentiated α cells exhibited many more genes bivalently marked by the activating H3K4me3 and repressing H3K27me3 histone modifications. This was particularly true for β cell signature genes involved in transcriptional regulation. Remarkably, thousands of these genes were in a monovalent state in β cells, carrying only the activating or repressing mark. Our epigenomic findings suggested that α to β cell reprogramming could be promoted by manipulating the histone methylation signature of human pancreatic islets. Indeed, we show that treatment of cultured pancreatic islets with a histone methyltransferase inhibitor leads to colocalization of both glucagon and insulin and glucagon and insulin promoter factor 1 (PDX1) in human islets and colocalization of both glucagon and insulin in mouse islets. Thus, mammalian pancreatic islet cells display cell-type–specific epigenomic plasticity, suggesting that epigenomic manipulation could provide a path to cell reprogramming and novel cell replacement-based therapies for diabetes. Pancreatic islets were collected post-mortem from 6 human donors and subjected to FACS to separate populations of alpha, beta, and exocrine cells. Depending on the availability of resulting material, sorted islet cell populations were used for H3K4me3, H3K27me3 ChIP-seq, or RNA-seq analysis. All ChIP-seq samples have a corresponding input from the same sample.
Project description:The goal of this experiment is to determine cell surface markers that are present in human beta cells or alpha cells but not both. Cells from human islets were FACS sorted and prepared as matched pairs of beta and alpha cells preparations.