Alpha 4 integrin deficiency in human CD34+ cells engenders a precocious erythroid differentiation ,but inhibits enucleation.
Ontology highlight
ABSTRACT: The functional impact of integrin expression in erythropoiesis has been previously emphasized through its decisive influence on erythroid cell-microenvironmental (matrix and cellular) interactions especially under conditions of stress. Beyond that in several in vitro studies the relationship between the two erythroid integrins, a4 and a5, has been incongruous in terms of a proliferative support, either synergistic or antagonistic, whereas a dominant influence of a4 integrin on terminal erythropoiesis in vitro and in vivo has been consistently emphasized. However, the specific cellular and molecular details of this effect have not been defined, especially for human cells. In the present study we have cultured human CD34+ progenitor cells with induced deficiency of a4 integrin (shRNAa4) under erythroid differentiation conditions, in which expanded erythroid progenitor cells are directed to terminal erythroid maturation stages in the absence of any microenvironmental influence. Our data documented that early proliferative expansion in cells lacking a4 expression is significantly limited, but, although erythroid differentiation can proceed normally to terminal stages, their enucleation is drastically impaired. This novel aspect of a4 integrin participation in the enucleation process in vitro resonates on the lack of in vivo enucleation of primitive erythroid cells lacking any integrin expression but affecting adult cells only under stress conditions.
Project description:Erythropoiesis in mammalian involves chromatin compaction which is initiated in the early stage of terminal differentiation. The proper condensation of chromatin is essential for the subsequent enucleation of erythroblast, but the characteristics of chromatin compaction and chromatin architecture changes in erythropoiesis are poorly understood. Here, we show that the formation of H3K9me3 long-range interactions which mediated heterochromatin three-dimensional rewiring participant in human erythroid chromatin condensation. TADs structure attenuated and boundary strength weakened globally but selectively maintaining in active chromatin region during terminal erythropoiesis. We demonstrate that the erythroid master regulators GATA1 safeguard the active chromatin structure and ensure the appropriate gene expression, under the chromatin condensation of human terminal erythropoiesis
Project description:Erythropoiesis in mammalian involves chromatin compaction which is initiated in the early stage of terminal differentiation. The proper condensation of chromatin is essential for the subsequent enucleation of erythroblast, but the characteristics of chromatin compaction and chromatin architecture changes in erythropoiesis are poorly understood. Here, we show that the formation of H3K9me3 long-range interactions which mediated heterochromatin three-dimensional rewiring participant in human erythroid chromatin condensation. TADs structure attenuated and boundary strength weakened globally but selectively maintaining in active chromatin region during terminal erythropoiesis. We demonstrate that the erythroid master regulators GATA1 safeguard the active chromatin structure and ensure the appropriate gene expression, under the chromatin condensation of human terminal erythropoiesis
Project description:Erythropoiesis in mammalian involves chromatin compaction which is initiated in the early stage of terminal differentiation. The proper condensation of chromatin is essential for the subsequent enucleation of erythroblast, but the characteristics of chromatin compaction and chromatin architecture changes in erythropoiesis are poorly understood. Here, we show that the formation of H3K9me3 long-range interactions which mediated heterochromatin three-dimensional rewiring participant in human erythroid chromatin condensation. TADs structure attenuated and boundary strength weakened globally but selectively maintaining in active chromatin region during terminal erythropoiesis. We demonstrate that the erythroid master regulators GATA1 safeguard the active chromatin structure and ensure the appropriate gene expression, under the chromatin condensation of human terminal erythropoiesis
Project description:Erythropoiesis in mammalian involves chromatin compaction which is initiated in the early stage of terminal differentiation. The proper condensation of chromatin is essential for the subsequent enucleation of erythroblast, but the characteristics of chromatin compaction and chromatin architecture changes in erythropoiesis are poorly understood. Here, we show that the formation of H3K9me3 long-range interactions which mediated heterochromatin three-dimensional rewiring participant in human erythroid chromatin condensation. TADs structure attenuated and boundary strength weakened globally but selectively maintaining in active chromatin region during terminal erythropoiesis. We demonstrate that the erythroid master regulators GATA1 safeguard the active chromatin structure and ensure the appropriate gene expression, under the chromatin condensation of human terminal erythropoiesis
Project description:Erythropoiesis in mammalian involves chromatin compaction which is initiated in the early stage of terminal differentiation. The proper condensation of chromatin is essential for the subsequent enucleation of erythroblast, but the characteristics of chromatin compaction and chromatin architecture changes in erythropoiesis are poorly understood. Here, we show that the formation of H3K9me3 long-range interactions which mediated heterochromatin three-dimensional rewiring participant in human erythroid chromatin condensation. TADs structure attenuated and boundary strength weakened globally but selectively maintaining in active chromatin region during terminal erythropoiesis. We demonstrate that the erythroid master regulators GATA1 safeguard the active chromatin structure and ensure the appropriate gene expression, under the chromatin condensation of human terminal erythropoiesis
Project description:Erythropoiesis in mammalian involves chromatin compaction which is initiated in the early stage of terminal differentiation. The proper condensation of chromatin is essential for the subsequent enucleation of erythroblast, but the characteristics of chromatin compaction and chromatin architecture changes in erythropoiesis are poorly understood. Here, we show that the formation of H3K9me3 long-range interactions which mediated heterochromatin three-dimensional rewiring participant in human erythroid chromatin condensation. TADs structure attenuated and boundary strength weakened globally but selectively maintaining in active chromatin region during terminal erythropoiesis. We demonstrate that the erythroid master regulators GATA1 safeguard the active chromatin structure and ensure the appropriate gene expression, under the chromatin condensation of human terminal erythropoiesis
Project description:Mammalian terminal erythropoiesis involves chromatin and nuclear condensation followed by enucleation. Late-stage erythroblasts undergo caspase-mediated nuclear opening formation that is important for nuclear condensation through partial release of histones. It remains unknown whether nuclear opening and histone release influence the three-dimensional (3D) genomic organization during terminal erythropoiesis. Here, we compared the genome wide 3D organization, chromatin accessibility, and transcriptome of the cultured mouse erythroid progenitors with and without the blocking of nuclear opening during differentiation. We found that terminal differentiation from the basophilic to orthochromatic stages of erythroblasts involves compaction and establishment of long-range interactions of the heterochromatin regions, which is associated with globally increased accessibility and upregulation of erythroid-related genes. Surprisingly, blocking of nuclear opening did not have a significant impact on 3D genomic organization, chromatin accessibility, or transcriptome despite the inhibition of histone release and nuclear condensation. Inhibition of nuclear opening also significantly affected enucleation. We further demonstrated this through a caspase-3 and 7 double knockout mouse model, which showed significant defects in nuclear opening and condensation with a compromise of enucleation in fetal erythroid progenitors. However, loss of these effector caspases had minimal effects on the red cell indices and survival of the recipient animals in a fetal liver cell transplantation model. Overall, these results indicate that nuclear opening and histone release may not be necessary for chromatin condensation and global transcriptome but are critical for nuclear condensation and efficient enucleation. These data also underline the robustness of enucleation despite the dysplastic or less condensed nucleus.
Project description:Mammalian terminal erythropoiesis involves chromatin and nuclear condensation followed by enucleation. Late-stage erythroblasts undergo caspase-mediated nuclear opening formation that is important for nuclear condensation through partial release of histones. It remains unknown whether nuclear opening and histone release influence the three-dimensional (3D) genomic organization during terminal erythropoiesis. Here, we compared the genome wide 3D organization, chromatin accessibility, and transcriptome of the cultured mouse erythroid progenitors with and without the blocking of nuclear opening during differentiation. We found that terminal differentiation from the basophilic to orthochromatic stages of erythroblasts involves compaction and establishment of long-range interactions of the heterochromatin regions, which is associated with globally increased accessibility and upregulation of erythroid-related genes. Surprisingly, blocking of nuclear opening did not have a significant impact on 3D genomic organization, chromatin accessibility, or transcriptome despite the inhibition of histone release and nuclear condensation. Inhibition of nuclear opening also significantly affected enucleation. We further demonstrated this through a caspase-3 and 7 double knockout mouse model, which showed significant defects in nuclear opening and condensation with a compromise of enucleation in fetal erythroid progenitors. However, loss of these effector caspases had minimal effects on the red cell indices and survival of the recipient animals in a fetal liver cell transplantation model. Overall, these results indicate that nuclear opening and histone release may not be necessary for chromatin condensation and global transcriptome but are critical for nuclear condensation and efficient enucleation. These data also underline the robustness of enucleation despite the dysplastic or less condensed nucleus.
Project description:Mammalian terminal erythropoiesis involves chromatin and nuclear condensation followed by enucleation. Late-stage erythroblasts undergo caspase-mediated nuclear opening formation that is important for nuclear condensation through partial release of histones. It remains unknown whether nuclear opening and histone release influence the three-dimensional (3D) genomic organization during terminal erythropoiesis. Here, we compared the genome wide 3D organization, chromatin accessibility, and transcriptome of the cultured mouse erythroid progenitors with and without the blocking of nuclear opening during differentiation. We found that terminal differentiation from the basophilic to orthochromatic stages of erythroblasts involves compaction and establishment of long-range interactions of the heterochromatin regions, which is associated with globally increased accessibility and upregulation of erythroid-related genes. Surprisingly, blocking of nuclear opening did not have a significant impact on 3D genomic organization, chromatin accessibility, or transcriptome despite the inhibition of histone release and nuclear condensation. Inhibition of nuclear opening also significantly affected enucleation. We further demonstrated this through a caspase-3 and 7 double knockout mouse model, which showed significant defects in nuclear opening and condensation with a compromise of enucleation in fetal erythroid progenitors. However, loss of these effector caspases had minimal effects on the red cell indices and survival of the recipient animals in a fetal liver cell transplantation model. Overall, these results indicate that nuclear opening and histone release may not be necessary for chromatin condensation and global transcriptome but are critical for nuclear condensation and efficient enucleation. These data also underline the robustness of enucleation despite the dysplastic or less condensed nucleus.
Project description:Condensation of chromatin prior to enucleation is an essential component of terminal erythroid maturation, and defects in this process are associated with inefficient erythropoiesis and anemia. However, the mechanisms involved in this phenomenon are not well understood. Here, we identify a novel role for the histone variant H2A.X in erythropoiesis. We find in multiple model systems that this histone is essential for normal maturation and the loss of H2A.X in erythroid cells results in dysregulation in expression of erythroid specific genes as well a nuclear condensation defect. In Addition, we demonstrate that erythroid maturation is characterized by phosphorylation at both S139 and Y142 during late stage erythropoiesis. Knockout of the kinase BAZ1B/WSTF results in loss of Y142 phosphorylation and similar to loss of H2A.X, a defect in nuclear condensation. In this study, we present a model in which post-translational modifications on histone H2A.X during terminal erythroid maturation leads to Caspase-Induced Chromatin Condensation (CICC). In this novel pathway, although apoptosis is specifically suppressed, aspects of the apoptotic pathway remain active to drive terminal erythroid maturation. Suggesting that terminal erythroid maturation is indeed is a unique form of apoptosis.