Project description:Erythropoiesis is a tightly controlled process. Although human and murine erythropoiesis are grossly similar, several aspects of these processes present significant differences. We have performed a label free quantification of proteins expressed during murine erythroid differentiation of primary cells with the aim to compare human and murine differentiations. Furthermore, we also analyzed the proteome of three murine cell lines, MEDEP, G1ER and Friend cells, to determine their similarities with the proteome of primary cells.
Project description:Deciphering cellular proteomes is critical for our understanding of erythropoiesis. To better comprehend commonly used models of erythropoiesis, we obtained absolute quantification of proteins expressed in cultured primary murine bone-marrow derived erythroblasts throughout erythroid differentiation. These data were compared to proteomes from Friend murine erythroleukemia (MEL), G1ER, and MEDEP cells. Overall, more than 7200 proteins were quantified in at least one of these models of murine erythropoiesis. Protein expression during differentiation of MEDEP cells was most similar to that of differentiating primary murine erythroid cells, while proteomes of Friend MEL and G1ER cells were more distantly related. Comparison of the proteomes of murine and human erythroblasts revealed species-linked variability, but these differences were not as dramatic as those observed comparing human and murine transcriptomes during erythroid differentiation. To functionally validate the differences between transcriptional and translational control, heme synthesis was inhibited in MEDEP cells and the effects on the transcriptome and the proteome examined. While heme deficiency had minimal global effect on the cellular proteome, globin proteins were significantly down regulated, supporting observations heme regulation of globin synthesis is tightly regulated at the protein level to avoid deleterious over production of globin chains. As predicted, heme deficiency led to up regulation of -aminolevulinic acid synthase 2 (Alas2) protein. Interestingly, Alas1 was upregulated at both the transcriptional and protein levels. Characterization of cellular proteomes during erythropoiesis has potential to yield insight into mechanistic principles of human disease, as well as reveal novel therapeutic targets.
Project description:Purpose:The purpose of this study is to create unbiased, stage-specific transcriptomes by RNA-seq analyses of pure populations of both murine and human erythroblasts at distinct developmental stages. Methods: Recently developed FACS-based methods (Chen et al, PNAS, Liu et al, Blood, Hu et al Blood) were employed to purify morphologically and functionally discrete populations of cells, each representing specific stages of terminal erythroid differentiation. RNA was prepared from these cells and subjected to RNA-seq analyses. Results: There were vast temporal changes in gene expression across the differentiation stages, with each stage exhibiting unique transcriptomes.Clustering and network analyses revealed that differing stage-specific patterns of expression across differentiation were transcriptionally enriched for genes of differing function. Numerous differences were present between human and murine transcriptomes, with significant variation in the global patterns of gene expression. Conclusions: These data provide a significant resource for studies of normal and perturbed erythropoiesis, allowing a deeper understanding of mechanisms of erythroid development, differentiation, and inherited and acquired disease. Both murine and human erythroblasts at distinct developmental stage mRNA profiles were generated by deep sequencing, in triplicate, using IlluminaHiSeq 2000.
Project description:Transcriptional profiling of murine erythroleukemia cells induced to differentiate Murine erythroleukemia (MEL) cells are derived from mice infected with the Friend erythroleukemia viral complex, which causes a lethal expansion of erythroid cells. The transformed, immortalized cells (MEL cells) isolated from infected mice are committed to erythroid differentiation, but are blocked roughly at the proerythoblast stage. Treatment with small, oxidized organic compounds like dimethyl sulfoxide or hydroxymethyl-bis-acetamide (HMBA) induce the cells to mature further, to roughly the erythroblast stage or beyond in some lines (Friend et al. 1971). During this induction, the amount of hemoglobin, some heme biosynthetic enzymes and other proteins characteristic of mature erythroid cells increases, largely as a result of changes in transcription (Aviv et al. 1976). A full description of changes in transcription of all mouse genes during this process is not available. To improve this situation, we have conducted transcriptional profiling of the RL5 line of MEL cells, using microarrays containing almost 7000 mouse genes. The RL5 line has a "random locus" containing a positive-negative selectable marker (HyTK) flanked by loxP sites, thus facilitating site-directed integration into the cells (Bouhassira et al. 1997; Feng et al. 1999; Molete et al. 2001). This particular line is not highly inducible, with less than half the cells accumulating large amounts of hemoglobin. However, they are advantageous for integration of expression constructs, which is our particular interest. MEL_RL5 cells were treated with 4 millimolar HMBA for 6 days to induce maturation, and RNA was isolated each day. Complementary DNA was synthesized and labeled with either Cy5 (red fluorescence) for the induced samples or Cy3 (green fluorescence) the untreated cells grown in parallel. For most time points, at least two independent experiments were run, some with dyes switched (SD). The microarrays were spotted at the PSU Microarray Facility. Hybridization was carried out in our laboratory, and hybridized chips were scanned on a GenePix scanner and quantified using GenePix software. The signals from each channel (red and green) were normalized so that the total red intensity equals the total green intensity. Data were filtered to remove "bad" spots, which are those in which the noise exceeded the signal. We calculated the median of the pixel intensities for each spot and standard deviation around the median, and with these values we computed a "modified Z-score" for each channel on each spot. A lenient threshold for the "modified Z-score" was applied to remove "bad" spots. After filtering, we performed global mean normalization for each chip, followed by lowess normalization for each chip to remove intensity-dependent effects.
Project description:Schneider RK, Schenone M, Kramann R, Ferreira MV, Joyce CE, Hartigan C, Beier F, Brümmendorf TH, Gehrming U, Platzbecker U, Buesche G, Chen MC, Waters CS, Chen E, Chu LP, Novina CD, Lindsley RC, Carr SA, Ebert BL. Nat Med, 2016.
Heterozygous deletion of RPS14 occurs in del(5q) MDS and has been linked to impaired erythropoiesis, characteristic of this disease subtype. We generated a murine model with conditional inactivation of Rps14 and demonstrated a p53-dependent erythroid differentiation defect with apoptosis at the transition from polychromatic to orthochromatic erythroblasts resulting in age-dependent progressive anemia, megakaryocyte dysplasia, and loss of hematopoietic stem cell (HSC) quiescence. Using quantitative proteomics, we identified significantly increased expression of proteins involved in innate immune signaling, particularly the heterodimeric S100A8/S100A9 proteins in purified erythroblasts. S100A8 expression was significantly increased in erythroblasts, monocytes and macrophages and recombinant S100A8 was sufficient to induce an erythroid differentiation defect in wild-type cells. We rescued the erythroid differentiation defect in Rps14 haploinsufficient HSCs by genetic inactivation of S100a8 expression. Our data link Rps14 haploinsufficiency to activation of the innate immune system via induction of S100A8/A9 and the p53-dependant erythroid differentiation defect in del(5q) MDS.
Project description:Alternative pre-mRNA splicing is a prevalent mechanism in mammals that promotes proteomic diversity, including expression of cell-type specific protein isoforms. We characterized a role for RBM38 (RNPC1) in regulation of alternative splicing during late erythroid differentiation. We used an affymetrix human exon junction (HJAY) splicing microarray to identify a panel of RBM38-regulated alternatively spliced transcripts. Using microarray databases, we noted high RBM38 expression levels in CD71+ erythroid cells and thus chose to examine RBM38 expression during erythroid differentiation of human hematopoietic stem cells, detecting enhanced RBM38 expression during late erythroid differentiation. In differentiated erythroid cells, we validated a subset of RBM38-regulated splicing events and determined that RBM38 regulates activation of Protein 4.1R (EPB41) exon 16 during late erythroid differentiation. Using Epb41 minigenes, Rbm38 was found to be a robust activator of exon 16 splicing. To further address the mechanism of RBM38-regulated alternative splicing, a novel mammalian protein expression system, followed by SELEX-Seq, was used to identify a GU-rich RBM38 binding motif. Lastly, using a tethering assay, we determined that RBM38 can directly activate splicing when recruited to a downstream intron. Together, our data support the role of RBM38 in regulating alternative splicing during erythroid differentiation. siRNA knockdown of RBM38 was perfomed in human MCF-7 breast cancer cells. The efficiency of RBM38 knockdown was monitored by western blot using an RBM38 antibody (Santa Cruz Biotechnology, SC-85873). We conducted HJAY exon and exon junction array profiling on RNAs from four siRBM38 treated MCF-7 samples vs. four sicontrol treated MCF-7 samples Control / knockdown comparison.
Project description:Ter-119 is a better murine erythroid selection marker than CD71 for bulk immunomics, murine bone marrow and fetal liver erythroid cells have different antimicrobial immune transcriptome signatures, murine bone marrow erythropoiesis is comprised of two branches In this study, we decided to benchmark erythroid cells’ selection and enrichment markers – CD71 and Ter-119 via bulk immune transcriptomics by Nanostring and perform bulk immune transcriptome profiling of Ter-119+ erythroid cells from the bone marrow and the fetal liver by Nanostring.
Project description:Transcriptional profiling of murine erythroleukemia cells induced to differentiate Murine erythroleukemia (MEL) cells are derived from mice infected with the Friend erythroleukemia viral complex, which causes a lethal expansion of erythroid cells. The transformed, immortalized cells (MEL cells) isolated from infected mice are committed to erythroid differentiation, but are blocked roughly at the proerythoblast stage. Treatment with small, oxidized organic compounds like dimethyl sulfoxide or hydroxymethyl-bis-acetamide (HMBA) induce the cells to mature further, to roughly the erythroblast stage or beyond in some lines (Friend et al. 1971). During this induction, the amount of hemoglobin, some heme biosynthetic enzymes and other proteins characteristic of mature erythroid cells increases, largely as a result of changes in transcription (Aviv et al. 1976). A full description of changes in transcription of all mouse genes during this process is not available. To improve this situation, we have conducted transcriptional profiling of the RL5 line of MEL cells, using microarrays containing almost 7000 mouse genes. The RL5 line has a "random locus" containing a positive-negative selectable marker (HyTK) flanked by loxP sites, thus facilitating site-directed integration into the cells (Bouhassira et al. 1997; Feng et al. 1999; Molete et al. 2001). This particular line is not highly inducible, with less than half the cells accumulating large amounts of hemoglobin. However, they are advantageous for integration of expression constructs, which is our particular interest. MEL_RL5 cells were treated with 4 millimolar HMBA for 6 days to induce maturation, and RNA was isolated each day. Complementary DNA was synthesized and labeled with either Cy5 (red fluorescence) for the induced samples or Cy3 (green fluorescence) the untreated cells grown in parallel. For most time points, at least two independent experiments were run, some with dyes switched (SD). The microarrays were spotted at the PSU Microarray Facility. Hybridization was carried out in our laboratory, and hybridized chips were scanned on a GenePix scanner and quantified using GenePix software. The signals from each channel (red and green) were normalized so that the total red intensity equals the total green intensity. Data were filtered to remove "bad" spots, which are those in which the noise exceeded the signal. We calculated the median of the pixel intensities for each spot and standard deviation around the median, and with these values we computed a "modified Z-score" for each channel on each spot. A lenient threshold for the "modified Z-score" was applied to remove "bad" spots. After filtering, we performed global mean normalization for each chip, followed by lowess normalization for each chip to remove intensity-dependent effects. Keywords: time-course
Project description:Terminal differentiation is characterized by a respecification of the global protein complement, as epitomized by erythrocytes, whose cytosol is ~98% globin. Remodeling of the proteome involves programmed elimination of generic cellular constituents in parallel with synthesis of cell-type-specific proteins. The erythroid proteome undergoes a rapid transition at the reticulocyte stage; however, the mechanisms driving elimination of preexisting cytosolic proteins are unidentified. UBE2O is a ubiquitin-conjugating enzyme expressed at elevated levels during late stage erythropoiesis. A Ube2o null mutation in mice results in anemia. Proteomic analysis of this mutant suggests that UBE2O is a broad-spectrum ubiquitinating enzyme that remodels the erythroid proteome. In particular, a hallmark of the reticulocyte to mature erythrocyte transition—ribosome elimination—is defective in Ube2o-/- mutants. UBE2O recognizes ribosomal proteins and other substrates directly, targeting them to proteasomes for degradation. Thus, in reticulocytes, and perhaps other highly differentiated cells, the induction of ubiquitinating factors may drive the transition from a complex to a simple proteome.