Project description:Transcriptional regulation is regulated by the organization of the genome into chromatin compartments and domains. Here, we present the detailed characteristics, including location of nucleosome-free regions, of several novel transcriptionally active/poised chromatin compartments exhibiting a range of transcriptional activities. These chromatin patterns illustrate how the salt solubility profile of a genomic region aids in the annotation of genes expressed in erythroid cells and contributes to the identification of functional features such as regulatory regions.
Project description:Erythrocytes represent the most abundant cell type of the bloodstream in all vertebrates. The principal feature that differenciates erythrocytes of non-mammals is that unlike mammals they mantain the nucleus in their terminal differentiation. While the main function associated to erythrocytes is the oxygen and carbon dioxide transport, some other functions, no less important, have been attributed to these cells. The focus of this study was to investigate the response of cultured chicken erythrocytes to bacterial lipopolysaccharide (LPS), bacterial peptidoglycan (PGN) and to the analog viral dsRNA Poly(I:C) using a comercial microarray platform from Agilent.
Project description:Erythrocytes represent the most abundant cell type of the bloodstream in all vertebrates. The principal feature that differenciates erythrocytes of non-mammals is that unlike mammals they mantain the nucleus in their terminal differentiation. While the main function associated to erythrocytes is the oxygen and carbon dioxide transport, some other functions, no less important, have been attributed to these cells. The focus of this study was to investigate the response of cultured chicken erythrocytes to bacterial lipopolysaccharide (LPS), bacterial peptidoglycan (PGN) and to the analog viral dsRNA Poly(I:C) using a comercial microarray platform from Agilent. Chicken erythrocytes were isolated from blood by twice Ficoll 1.007 density gradient centrifugations. For primary cell culture, erythrocytes were resuspended in DMEM (PAA Laboratories) supplemented with 10% heat-inactivated fetal bovine serum (FBS, PAA Laboratories) and the antibiotic Primocin (100 μg/ml, Invivogen) at a density of 7.5x106 cells/ml in six well cell culture plates (NUNC) and cultured at 37ºC and 5% CO2. Erythrocytes were stimulated with LPS from E. coli (serotype 0111:B4, Sigma) and Poly(I:C) (Invivogen) at 50 μg/ml, and with peptidoglycan from E.coli (0111:B4, Invivogen) at 5 μg/ml. All culture plates were incubated for 12h. Total RNA was extracted from the cultures using 1 ml of Tri Reagent (Sigma) following the manufacturer’s instructions with minor modifications. Quantity and integrity was analyzed by Nanodrop1000 (ThermoScientific) and Bioanalyzer 2100 (Agilent Technologies) respectively. Three biological replicates were used.
Project description:Understanding gene expression changes over the lifespan of cells is of fundamental interest and gives important insights into processes related to maturation and ageing. This study was undertaken to understand the global transcriptome changes associated with ageing in fish erythrocytes. Fish erythrocytes retain their nuclei throughout their lifetime and they are transcriptionally and translationally active. However, they lose important functions during their lifespan in the circulation. We separated rainbow trout (Oncorhynchus mykiss) erythrocytes into young and old fractions using fixed angle-centrifugation and analyzed transcriptome changes using RNA sequencing (RNA-seq) technology and quantitative real-time PCR. We found 930 differentially expressed between young and old erythrocyte fractions; 889 of these showed higher transcript levels in young, while only 34 protein-coding genes had higher transcript levels in old erythrocytes. In particular ion binding, signal transduction, membrane transport, and various enzyme classes are affected in old erythrocytes. The transcripts with higher levels in old erythrocytes were associated with 7 different GO terms within biological processes and 9 within molecular functions and cellular components respectively. Our study furthermore found several highly abundant transcripts as well as a number of differentially expressed genes for which the protein products are currently not known revealing the gaps of knowledge in most non-mammalian vertebrates. Our data provide the first insight into changes involved in ageing on the transcriptional level and thus opens new perspectives for the study of maturation processes in fish erythrocytes.
Project description:Transcriptional regulation is impacted by multiple layers of genome organization. Here, we report that immune genes were associated with H3K4me3 and H3K27ac.Our data provide a genome-wide profile of chromatin signatures for immune genes in chicken polychromatic erythrocytes.
Project description:Chicken erythrocytes are nucleated cells often referred to as transcriptionally inactive, although the epigenetic changes and chromatin remodeling that mediate transcriptional repression and the extent of gene silencing during avian terminal erythroid differentiation are not fully understood. Here we characterized the changes in gene expression, chromatin accessibility, genome organization, and chromatin nuclear disposition during the terminal stages of erythropoiesis in chicken and found a complex chromatin reorganization at different genomic scales. We identified a robust decrease in transcription in erythrocytes. Nevertheless, a set of genes maintains their expression in erythrocytes, including genes involved in RNA pol II promoter-proximal pausing. Erythrocytes exhibit an inverted nuclear architecture and reposition euchromatin towards the nuclear periphery together with the paused RNA polymerase. In erythrocytes, chromatin domains are partially lost genome-wide except at mini domains retained around paused promoters. Our results suggest that promoter-proximal pausing of the RNA pol II participates in the transcriptional regulation of the erythroid genome and highlight the role of RNA polymerase in the maintenance of local chromatin organization.
Project description:Chicken erythrocytes are nucleated cells often referred to as transcriptionally inactive, although the epigenetic changes and chromatin remodeling that mediate transcriptional repression and the extent of gene silencing during avian terminal erythroid differentiation are not fully understood. Here we characterized the changes in gene expression, chromatin accessibility, genome organization, and chromatin nuclear disposition during the terminal stages of erythropoiesis in chicken and found a complex chromatin reorganization at different genomic scales. We identified a robust decrease in transcription in erythrocytes. Nevertheless, a set of genes maintains their expression in erythrocytes, including genes involved in RNA pol II promoter-proximal pausing. Erythrocytes exhibit an inverted nuclear architecture and reposition euchromatin towards the nuclear periphery together with the paused RNA polymerase. In erythrocytes, chromatin domains are partially lost genome-wide except at mini domains retained around paused promoters. Our results suggest that promoter-proximal pausing of the RNA pol II participates in the transcriptional regulation of the erythroid genome and highlight the role of RNA polymerase in the maintenance of local chromatin organization.
Project description:Chicken erythrocytes are nucleated cells often referred to as transcriptionally inactive, although the epigenetic changes and chromatin remodeling that mediate transcriptional repression and the extent of gene silencing during avian terminal erythroid differentiation are not fully understood. Here we characterized the changes in gene expression, chromatin accessibility, genome organization, and chromatin nuclear disposition during the terminal stages of erythropoiesis in chicken and found a complex chromatin reorganization at different genomic scales. We identified a robust decrease in transcription in erythrocytes. Nevertheless, a set of genes maintains their expression in erythrocytes, including genes involved in RNA pol II promoter-proximal pausing. Erythrocytes exhibit an inverted nuclear architecture and reposition euchromatin towards the nuclear periphery together with the paused RNA polymerase. In erythrocytes, chromatin domains are partially lost genome-wide except at mini domains retained around paused promoters. Our results suggest that promoter-proximal pausing of the RNA pol II participates in the transcriptional regulation of the erythroid genome and highlight the role of RNA polymerase in the maintenance of local chromatin organization.
Project description:Chicken erythrocytes are nucleated cells often referred to as transcriptionally inactive, although the epigenetic changes and chromatin remodeling that mediate transcriptional repression and the extent of gene silencing during avian terminal erythroid differentiation are not fully understood. Here we characterized the changes in gene expression, chromatin accessibility, genome organization, and chromatin nuclear disposition during the terminal stages of erythropoiesis in chicken and found a complex chromatin reorganization at different genomic scales. We identified a robust decrease in transcription in erythrocytes. Nevertheless, a set of genes maintains their expression in erythrocytes, including genes involved in RNA pol II promoter-proximal pausing. Erythrocytes exhibit an inverted nuclear architecture and reposition euchromatin towards the nuclear periphery together with the paused RNA polymerase. In erythrocytes, chromatin domains are partially lost genome-wide except at mini domains retained around paused promoters. Our results suggest that promoter-proximal pausing of the RNA pol II participates in the transcriptional regulation of the erythroid genome and highlight the role of RNA polymerase in the maintenance of local chromatin organization.