Project description:Red pulp macrophages of the spleen mediate daily turnover of billions of senescent erythrocytes. However, the exact molecules and mechanisms involved in sequestration of senescent erythrocytes, their recognition and ultimately their turnover remain unclear and are currently subject to debate. In this study we provide evidence that the splenic environment is of substantial importance in facilitating erythrocyte turnover through induction of haemolysis. Detailed characterization of human spleen and its red pulp macrophages lead to the identification of a population of erythrocytes devoid of haemoglobin without fully disintegrating, so-called erythrocyte ghosts. By in-vivo imaging and transfusion experiments we established that senescent erythrocytes are subject to haemolysis specifically within the spleen. We show that aged erythrocytes are captured by the extracellular matrix within the red pulp of the spleen and that their retention under low shear conditions is key in driving haemolysis. In contrast to senescent erythrocytes, the erythrocyte ghost shells were found to be prone to recognition and breakdown by red pulp macrophages. As such, these data put forward haemolysis as an efficient mechanism for the turnover of senescent erythrocytes which alters our current understanding on how erythrocyte turnover is regulated.
Project description:Dhh negatively regulates multiple stages of erythrocyte differentiation. In Dhh-deficient bone marrow, the common myeloid progenitor (CMP) population was increased, but differentiation from CMP to granulocyte/macrophage progenitor was decreased, and the mature granulocyte population was decreased, compared with wild-type (WT). In contrast, differentiation from CMP to megakaryocyte/erythrocyte progenitor was increased, and the megakaryocyte/erythrocyte progenitor population was increased. In Dhh-deficient spleen and bone marrow, BFU-Es and erythroblast populations were increased compared with WT. During recovery of hematopoiesis after irradiation, and under conditions of stress-induced erythropoiesis, erythrocyte differentiation was accelerated in both spleen and bone marrow of Dhh-deficient mice compared with WT. To investigate possible mechanisms for its regulation of erythropoiesis we carried out RNAsequencing on Facs-sorted erythroblast population II (CD71+Ter119+) cells from Dhh-/-, Dhh+/- and WR mice.
Project description:Transcriptional regulation is impacted by multiple layers of genome organization. Here, we identified and mapped out all the transcriptionally active chromosomal domains in the chicken immature erythrocyte genome, including the known β- and α-globin domains, by combining a powerful chromatin fractionation method with next generation DNA and RNA sequencing. Two biological replicates of total RNA were sequenced to characterize genes in chicken erythrocyte cells
Project description:This collection contains microRNA expression profiling data for samples purified from umbilical cord blood, belonging to one of the followiing populations: MEP, MEGA1, MEGA2, ERY1, ERY2, ERY3. MEP: megakaryocyte-erythrocyte precursors (defined by CD34+ CD38+ IL-3Ra- CD45RA- ); MEGA1: megakaryocyte population 1 (defined by CD34+ CD61+ CD41+ CD45- ); MEGA2: megakaryocyte population 2 (defined by CD34- CD61+ CD41+ CD45- ); ERY1: erythrocyte population 1 (defined by CD34+ CD71+ GlyA- ); ERY2: erythrocyte population 2 (defined by CD34- CD71+ GlyA- ); ERY3: erythrocyte population 3 (defined by CD34- CD71+ GlyA+ ). Keywords: microRNA, miRNA, MEP, megakaryocyte, erythrocyte, lineage specification Varied numbers of samples were analyzed per population. Each sample came from one donor. Data were normalized as described (Lu et al., Nature 435, 834-838, 2005) with modifications. Average readings from water-only labeled samples were used for probe-specific background subtraction. Linear normalization among different bead sets for the same sample was performed using readings from 2 post-control probes with equal contribution. Sample normalization was subsequently carried out assuming equal total fluorescence readings.
Project description:Transcriptional regulation is impacted by multiple layers of genome organization. Here, we identified and mapped out all the transcriptionally active chromosomal domains in the chicken immature erythrocyte genome, including the known β- and α-globin domains, by combining a powerful chromatin fractionation method with next generation DNA and RNA sequencing.
Project description:Transcriptional regulation is impacted by multiple layers of genome organization. Here, we report that highly expressed genes were associated with H3K4me3 and H3K27ac.Our data provide a genome-wide profile of chromatin signatures in relation to expression levels in chicken immature erythrocytes. Examination of two different histone modifications in immature erythrocyte cells
Project description:We developed a system to study the DNA replication-independent turnover nucleosomes containing the histone variant H3.3 in mammalian cells. By measuring the genome-wide incorporation of H3.3 at different time points following epitope-tagged H3.3 expression, we find three categories of H3.3-nucleosome turnover in vivo: rapid turnover, intermediate turnover and, specifically at telomeres, slow turnover. Our data indicate that H3.3-containing nucleosomes at enhancers and promoters undergo a rapid turnover that is associated with active histone modification marks including H3K4me1, H3K4me3, H3K9ac, H3K27ac and the histone variant H2A.Z. The rate of turnover is negatively correlated with H3K27me3 at regulatory regions and with H3K36me3 at gene bodies. Examination of incorporation dynamics of histone variant H3.3