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Objective To explore potential function of IKAROS family zinc finger 1 (Ikzf1) in terminal erythroid differentiation. Methods Single-cell regulatory network inference and clustering (SCENIC) was used to predict transcription factors of terminal erythroid differentiation based on single cell transcriptomes of human and mouse bone marrow erythroid cells. Expression of the predicted Ikzf1 during terminal erythroid differentiation was acquired from public RNA-seq data and validated by RT-qPCR. Short hairpin RNA (shRNA) interference was performed to knock down Ikzf1 in mouse erythroid cells from fetal liver with a GFP cassette to mark successfully transfected cells. The knockdown efficiency in GFP+ cells was verified by RT-qPCR. The effect of Ikzf1 knockdown on erythroid differentiation and enucleation was analyzed by flow cytometry. Results SCENIC predicted that the transcription factor Ikzf1 regulated both human and mouse erythroid differentiation. RNA-seq data and RT-qPCR showed highly expressed Ikzf1 at proerythroblast and basophilic erythroblast stages of terminal erythroid differentiation. Ikzf1 expression was indeed down-regulated by shRNA in erythroid cells from mouse fetal liver. Flow cytometry analysis showed that knockdown of Ikzf1 affected terminal differentiation and significantly reduced the ratio of erythroid enucleation (P＜ 0.05). Conclusions Transcription factor Ikzf1 is highly expressed in early stage erythroblasts and involved in terminal erythroid differentiation as well as enucleation.

Objective To explore potential function of IKAROS family zinc finger 1 (Ikzf1) in terminal erythroid differentiation. Methods Single-cell regulatory network inference and clustering (SCENIC) was used to predict transcription factors of terminal erythroid differentiation based on single cell transcriptomes of human and mouse bone marrow erythroid cells. Expression of the predicted Ikzf1 during terminal erythroid differentiation was acquired from public RNA-seq data and validated by RT-qPCR. Short hairpin RNA (shRNA) interference was performed to knock down Ikzf1 in mouse erythroid cells from fetal liver with a GFP cassette to mark successfully transfected cells. The knockdown efficiency in GFP+ cells was verified by RT-qPCR. The effect of Ikzf1 knockdown on erythroid differentiation and enucleation was analyzed by flow cytometry. Results SCENIC predicted that the transcription factor Ikzf1 regulated both human and mouse erythroid differentiation. RNA-seq data and RT-qPCR showed highly expressed Ikzf1 at proerythroblast and basophilic erythroblast stages of terminal erythroid differentiation. Ikzf1 expression was indeed down-regulated by shRNA in erythroid cells from mouse fetal liver. Flow cytometry analysis showed that knockdown of Ikzf1 affected terminal differentiation and significantly reduced the ratio of erythroid enucleation (P＜ 0.05). Conclusions Transcription factor Ikzf1 is highly expressed in early stage erythroblasts and involved in terminal erythroid differentiation as well as enucleation. [ABSTRACT FROM AUTHOR]

Objective To investigate the expression and function of protein tyrosine phosphatase 4A3(PTP4A3) in terminal erythroid differentiation and underlying molecular mechanism. Methods RT-qPCR was used to detect the expression of Ptp4a3 during terminal differentiation. Knockdown of Ptp4a3 expression in mouse fetal liver induced erythroid differentiation system by short hairpin RNA(shRNA) interference, the knockdown efficiency was verified by RT-qPCR after GFP positive cells were sorted by flow cytometry, and the effect of Ptp4a3 knockdown on erythroid differentiation and enucleation was detected by flow cytometry. Transcriptional profiling was performed to explore the potential downstream pathways of Ptp4a3. Results Ptp4a3 was among the top 100 ranked expressing genes during mouse terminal erythroid differentiation, and its expression gradually increased following the differentiation process. In mouse fetal liver-derived erythroid cells, Ptp4a3 was successfully knocked down by shRNA interference. Flow cytometry analysis showed that Ptp4a3 knockdown significantly decreased the proportion of enucleated erythrocytes(P＜0.05). Transcriptome analysis revealed that Ptp4a3 knockdown resulted in upregulation of cell cycle-related genes. Conclusions PTP4A3 is highly expressed in late stage of terminal erythroid differentiation. Knockdown Ptp4a3 significantly reduces enucleation erythroid of cells.

Anemia is the most prevalent nutrition-related disorder worldwide. Zinc is an essential trace element for various biological processes in the body, and zinc deficiency has been associated with anemia in humans. However, the molecular mechanisms by which zinc availability alters red blood cell development remain uncertain. The present study identifies the essentiality of zinc during erythroid development, particularly for normal heme biosynthesis. G1E-ER4 mouse cells were used as an in vitro model of terminal erythroid differentiation, which featured elevated cellular zinc content by development. Restriction of zinc import compromised the rate of heme and α-globin production and, thus, the hemoglobinization of the erythroid progenitors. Heme is synthesized by the incorporation of iron into protoporphyrin. The lower heme production under zinc restriction was not due to changes in iron but was attributable to less porphyrin synthesis. The requirement of adequate zinc for erythroid heme metabolism was confirmed in another erythropoietic cell model, MEL-DS19. Additionally, we found that a conventional marker of iron deficiency anemia, the ZnPP-to-heme ratio, responded to zinc restriction differently from iron deficiency. Collectively, our findings define zinc as an essential nutrient integral to erythroid heme biosynthesis and, thus, a potential therapeutic target for treating anemia and other erythrocyte-related disorders. [ABSTRACT FROM AUTHOR]

Anemia is the most prevalent nutrition-related disorder worldwide. Zinc is an essential trace element for various biological processes in the body, and zinc deficiency has been associated with anemia in humans. However, the molecular mechanisms by which zinc availability alters red blood cell development remain uncertain. The present study identifies the essentiality of zinc during erythroid development, particularly for normal heme biosynthesis. G1E-ER4 mouse cells were used as an in vitro model of terminal erythroid differentiation, which featured elevated cellular zinc content by development. Restriction of zinc import compromised the rate of heme and α-globin production and, thus, the hemoglobinization of the erythroid progenitors. Heme is synthesized by the incorporation of iron into protoporphyrin. The lower heme production under zinc restriction was not due to changes in iron but was attributable to less porphyrin synthesis. The requirement of adequate zinc for erythroid heme metabolism was confirmed in another erythropoietic cell model, MEL-DS19. Additionally, we found that a conventional marker of iron deficiency anemia, the ZnPP-to-heme ratio, responded to zinc restriction differently from iron deficiency. Collectively, our findings define zinc as an essential nutrient integral to erythroid heme biosynthesis and, thus, a potential therapeutic target for treating anemia and other erythrocyte-related disorders.

Fine-resolution differentiation trajectories of adult human hematopoietic stem cells (HSCs) involved in the generation of red cells is critical for understanding dynamic developmental changes that accompany human erythropoiesis. Using single-cell RNA sequencing (scRNA-seq) of primary human terminal erythroid cells (CD34-CD235a+) isolated directly from adult bone marrow (BM) and umbilical cord blood (UCB), we documented the transcriptome of terminally differentiated human erythroblasts at unprecedented resolution. The insights enabled us to distinguish polychromatic erythroblasts (PolyEs) at the early and late stages of development as well as the different development stages of orthochromatic erythroblasts (OrthoEs). We further identified a set of putative regulators of terminal erythroid differentiation and functionally validated three of the identified genes, AKAP8L, TERF2IP, and RNF10, by monitoring cell differentiation and apoptosis. We documented that knockdown of AKAP8L suppressed the commitment of HSCs to erythroid lineage and cell proliferation and delayed differentiation of colony-forming unit-erythroid (CFU-E) to the proerythroblast stage (ProE). In contrast, the knockdown of TERF2IP and RNF10 delayed differentiation of PolyE to OrthoE stage. Taken together, the convergence and divergence of the transcriptional continuums at single-cell resolution underscore the transcriptional regulatory networks that underlie human fetal and adult terminal erythroid differentiation. [ABSTRACT FROM AUTHOR]

Terminal erythroid differentiation occurs in the bone marrow, within specialized niches termed erythroblastic islands. These functional units consist of a macrophage surrounded by differentiating erythroblasts and have been described more than five decades ago, but their function in the pathophysiology of erythropoiesis has remained unclear until recently. Here we propose that the central macrophage in the erythroblastic island contributes to the pathophysiology of anemia of inflammation. After introducing erythropoiesis and the interactions between the erythroblasts and the central macrophage within the erythroblastic islands, we will discuss the immunophenotypic characterization of this specific subpopulation of macrophages. We will then integrate these concepts into the currently known pathophysiological drivers of anemia of inflammation and address the role of the central macrophage in this disorder. Finally, as a means of furthering our understanding of the various concepts, we will discuss the differences between murine and rat models with regard to developmental and stress erythropoiesis in an attempt to define a model system representative of human pathophysiology. [ABSTRACT FROM AUTHOR]

Abstract: In differentiating red blood cells (RBCs) of the chick embryo, the synthesis of carbonic anhydrase (CAII) and pyrimidine 5′-nucleotidase (P5N-I) is triggered by the hypoxic mediators norepinephrine and adenosine via receptor-mediated cAMP formation. The process is accompanied by the induction of IFR1 and TOB which are putative regulators of transcription or translation in different cell types. The present investigation studied the erythroid TOB and IFR1 expression: mRNA and protein are up-regulated in post-mitotic RBCs from D11–19 treated with cAMP-elevating agonists. In contrast, immature RBCs of early embryos (D5–7) fail to synthesize a significant amount of IFR1/TOB. In D11 RBCs, TOB and IFR1 are cytosolic proteins with different half-lives (TOB<4h, IFR1>12h). Cytosolic fractionation characterized TOB as a free soluble protein while the abundant IFR1 (c max∼3μM) is completely associated with the ribosomal fraction. A putative function of both proteins as translational regulators is discussed. [Copyright &y& Elsevier]

The dynamics of gene expression during terminal erythroid differentiation have been examined in three murine models; the erythroleukaemia cell line HCD-57 and splenic erythroblasts isolated from mice treated with either the anaemia-inducing strain of Friend virus (FVA cells) or the haemolytic agent phenylhydrazine (PHZ cells). In response to erythropoietin (EPO) and haemin, HCD-57 cells proliferated and synthesized haemoglobin, but failed to complete terminal differentiation as indicated by lack of change in both gene expression and morphological appearance. In contrast, EPO-induced terminal differentiation in FVA and PHZ cells in vitro was accompanied by increases in haemoglobin positivity, morphological maturation and a shared pattern of gene expression. EPO receptor (EPO-R) mRNA levels peaked before globin gene expression which was maximal at 24 h. Peak GATA-1 and EKLF mRNA levels also preceded the globin gene peak, but the highest NF-E2 levels coincided with maximal globin levels, suggesting a role for NF-E2 in the maintenance, rather than the initiation of globin gene expression. Peak expression of δ-aminolaevulinic acid synthase (ALAS) coincided with peak globin expression. FVA and PHZ cells represent more effective models than the HCD-57 cell line for the investigation of erythroid gene expression during EPO-regulated terminal erythropoiesis. [ABSTRACT FROM AUTHOR]

Fine-resolution differentiation trajectories of adult human hematopoietic stem cells (HSCs) involved in the generation of red cells is critical for understanding dynamic developmental changes that accompany human erythropoiesis. Using single-cell RNA sequencing (scRNA-seq) of primary human terminal erythroid cells (CD34 - CD235a + ) isolated directly from adult bone marrow (BM) and umbilical cord blood (UCB), we documented the transcriptome of terminally differentiated human erythroblasts at unprecedented resolution. The insights enabled us to distinguish polychromatic erythroblasts (PolyEs) at the early and late stages of development as well as the different development stages of orthochromatic erythroblasts (OrthoEs). We further identified a set of putative regulators of terminal erythroid differentiation and functionally validated three of the identified genes, AKAP8L , TERF2IP , and RNF10 , by monitoring cell differentiation and apoptosis. We documented that knockdown of AKAP8L suppressed the commitment of HSCs to erythroid lineage and cell proliferation and delayed differentiation of colony-forming unit-erythroid (CFU-E) to the proerythroblast stage (ProE). In contrast, the knockdown of TERF2IP and RNF10 delayed differentiation of PolyE to OrthoE stage. Taken together, the convergence and divergence of the transcriptional continuums at single-cell resolution underscore the transcriptional regulatory networks that underlie human fetal and adult terminal erythroid differentiation., Competing Interests: The authors declare no competing interest.