Iron and Heme Coordinate Erythropoiesis through HRI-Mediated Regulation of Protein Translation and Gene Expression
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ABSTRACT:
PROVIDER: PRJNA488955 | ENA |
REPOSITORIES: ENA
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Project description:Iron and heme play central roles in red blood cell production. However, the mechanisms by which iron and heme levels coordinate erythropoiesis remain incompletely understood. HRI is a heme-regulated kinase that controls translation by phosphorylating eIF2a. Here, we investigate the global impact of iron, heme and HRI on protein translation in vivo in murine primary erythroblasts using ribosome profiling. By defining the underlying changes in translation during iron and HRI deficiencies, we validate known regulators of this process, including Atf4, and identify novel pathways such as co-regulation of ribosomal protein mRNA translation. Surprisingly, we found that heme and HRI pathways, but not iron-regulated pathways, mediate the major protein translational and transcriptional responses to iron deficiency in erythroblasts in vivo and thereby identify previously unappreciated regulators of erythropoiesis. Our genome-wide study uncovers the major impact of the HRI-mediated integrated stress response for the adaptation to iron deficiency anemia.
2018-09-03 | GSE119365 | GEO
Project description:Heme-regulated eIF2α kinase (HRI) is essential for the survival of erythroid precursors in iron and heme deficiency and it also plays a protective role in red blood cell diseases of erythroid protoporphyria and β-thalassemia. In this study, we demonstrated for the first time the impairment of GATA-1 and Fog-1 expressions in iron deficiency and the impairment of GATA-1 expression in β-thalassemia. Furthermore, HRI is necessary to maintain the GATA-1/Fog-1 induced functions in erythroid differentiation, cell cycle and cell survival by sustaining both expressions of GATA-1 and Fog-1 in iron deficiency and in β-thalassemia. Keywords: Genetic modification
2009-06-30 | GSE6808 | GEO
Project description:Erythropoietic homeostasis is coordinated by erythroblast development and challenged by a number of genetic diseases including polycythemia vera. Erythroblasts and central macrophages form erythroblastic islands to provide a specific environment for erythropoiesis. However, how central macrophages interplay with erythroblasts during erythropoiesis remains to be further clarified. In this study, we found that erythroid-specific TFPI knockout decreased the number of erythroblasts under both steady-state and stress conditions, and the function of TFPI in erythropoiesis was mediated by macrophages. TFPI affects the downstream heme synthesis pathway of central macrophages, as shown by RNA sequencing analysis, and the deletion of TFPI reduced the heme content of macrophages by inhibiting ferrochelatase (Fech) expression. Our results show that TFPI plays an important role in the regulation of erythropoiesis and reveal a new mechanism of interplay between erythroblasts and macrophages. TFPI will also provide a new potential treatment strategy for polycythemia vera.
2024-03-01 | GSE224994 | GEO
Project description:Increasing fetal hemoglobin (HbF) levels in adult red blood cells provides clinical benefit to patients with sickle cell disease and some forms of beta-thalassemia. To identify potentially druggable HbF regulators in adult human erythroid cells, we employed a protein kinase-domain focused CRISPR/Cas9-based genetic screen with a newly optimized sgRNA scaffold. The screen uncovered the heme-regulated inhibitor HRI (also known as EIF2AK1), an erythroid-specific kinase that controls protein translation, as an HbF repressor. HRI depletion markedly increased HbF production in a specific manner and reduced sickling in cultured erythroid cells. Diminished expression of the HbF repressor BCL11A accounted in large part for the effects of HRI depletion. Taken together, these results suggest HRI as a potential therapeutic target for hemoglobinopathies.
2018-07-20 | GSE115687 | GEO
Project description:Increasing fetal hemoglobin (HbF) provides clinical benefit in patients with sickle cell disease (SCD). We recently identified heme-regulated inhibitor (HRI, EIF2AK1) as a novel HbF regulator. Since HRI is an erythroid-specific protein kinase it presents a potential target for pharmacologic intervention. We find that maximal HbF induction requires >80-85% HRI depletion. As it remains unclear whether this degree of HRI inhibition can be achieved pharmacologically, we explored whether HRI knockdown can be combined with pharmacologic HbF inducers to achieve greater HbF production and minimize potential adverse effects associated with treatments. Strongly cooperative HbF induction was observed when HRI depletion was combined with exposure to pomalidomide or the EHMT1/2 inhibitor UNC0638, but not hydroxyurea. Mechanistically, reduction in the levels of the HbF repressor BCL11A reflected the cooperativity of HRI loss and pomalidomide treatment, whereas UNC0638 did not modulate BCL11A levels. In conjunction with HRI loss, pomalidomide maintained its HbF inducing activity at 10-fold lower concentrations, at which condition there were minimal observed detrimental effects on erythroid cell maturation and viability as well as fewer alterations in the erythroid transcriptome. In sum, this study provides a foundation for the exploration of combining future small molecule HRI inhibitors with additional pharmacologic HbF inducers to maximize HbF production and preserve erythroid cell functionality for the treatment of SCD and other hemoglobinopathies.
2020-09-21 | GSE150341 | GEO
Project description: Not available
| S-EPMC5790126 | biostudies-literature
Project description: Not available
| S-EPMC6533081 | biostudies-literature
Project description:Splenic red pulp macrophages (RPM) degrade senescent erythrocytes and recycle heme-associated iron. The transcription factor Spic is selectively expressed by RPM and is required for their development, but the physiologic stimulus inducing Spic is unknown. Here, we report that Spic also regulated the development of F4/80+VCAM+ bone marrow macrophages (BMM) and that Spic expression in BMM and RPM development was induced by heme, a metabolite of erythrocyte degradation. Pathologic hemolysis induced loss of RPM and BMM due to excess heme but induced Spic in monocytes to generate new RPM and BMM. Spic expression in monocytes was constitutively inhibited by the transcriptional repressor Bach1. Heme induced proteasome-dependent BACH1 degradation and rapid Spic derepression. Further, cysteine-proline dipeptide motifs in BACH1 that mediate heme-dependent degradation were necessary for Spic induction by heme. These findings are the first example of metabolite-driven differentiation of a tissue-resident macrophage subset and provide new insight into iron homeostasis. Global gene expression pattern of bone marrow-derived macrophages generated with GM-CSF in vitro and treated with heme were compared to those treated with vehicle at 6 hours, 24 hours, and 72 hours after treatment.
2014-03-14 | GSE46983 | GEO
Project description:Heme Deficient or Wild Type (normal heme) for 6 hrs with iron chelation by BPS. Keywords: Cell Type Comparison
2005-10-18 | GSE3470 | GEO
Project description:Splenic red pulp macrophages (RPM) degrade senescent erythrocytes and recycle heme-associated iron. The transcription factor Spic is selectively expressed by RPM and is required for their development, but the physiologic stimulus inducing Spic is unknown. Here, we report that Spic also regulated the development of F4/80+VCAM+ bone marrow macrophages (BMM) and that Spic expression in BMM and RPM development was induced by heme, a metabolite of erythrocyte degradation. Pathologic hemolysis induced loss of RPM and BMM due to excess heme but induced Spic in monocytes to generate new RPM and BMM. Spic expression in monocytes was constitutively inhibited by the transcriptional repressor Bach1. Heme induced proteasome-dependent BACH1 degradation and rapid Spic derepression. Further, cysteine-proline dipeptide motifs in BACH1 that mediate heme-dependent degradation were necessary for Spic induction by heme. These findings are the first example of metabolite-driven differentiation of a tissue-resident macrophage subset and provide new insight into iron homeostasis. Global gene expression pattern of bone marrow-derived macrophages generated with GM-CSF in vitro and treated with heme were compared to those treated with vehicle at 6 hours, 24 hours, and 72 hours after treatment. GM-CSF cultures of Spic(igfp/igfp) BM cells were treated with heme (80 µm) or vehicle after 6 days in culture. Adherent fraction of cells were harvested 6 hours, 24 hours, and 72 hours after treatment and RNA was isolated using an RNeasy mini kit (Qiagen) and submitted for amplification, labeling and hybridization. Expression values were analyzed after RMA quantile normalization using ArrayStar software (DNASTAR).
2014-03-14 | E-GEOD-46983 | biostudies-arrayexpress