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Extensively self-renewing erythroblasts derived from transgenic ?-yac mice is a novel model system for studying globin switching and erythroid maturation.

ABSTRACT: Globin gene regulation occurs in the context of a maturing erythroid cell, which is undergoing significant changes in chromatin structure and gene expression. There are few model systems available that facilitate studies of globin gene regulation in the context of erythroid maturation. Extensively self-renewing erythroblasts (ESREs) are a nontransformed model of erythroid maturation derived from murine fetal liver or yolk sac. Imaging flow cytometry and RNA-seq studies demonstrate that ESREs functionally and molecularly model erythroid maturation. To address the need for a model system that also recapitulates human globin switching, ESREs were derived from mice transgenic for the complete human ?-globin locus (?-yac ESREs). ?-yac ESREs express ?-globin from the transgenic human locus, with minimal ?-globin expression. When treated with hydroxyurea or inhibitors to histone deacetylases, DNA methyltransferases, or the histone demethylase lysine specific demethylase 1 (LSD1), ?-Yac ESREs significantly increase their ?-globin expression, demonstrating their utility for studying agents that influence maturational globin switching. ?-yac ESREs were further used to characterize the secondary effects of LSD1 inhibition on erythroid maturation, with inhibition of LSD1 resulting in altered cell and nuclear size, prolonged Kit expression, and decreased rates of enucleation consistent with impaired maturation. Taken together, these studies demonstrate that ?-yac ESREs have significant utility for identifying modulators of maturational globin switching as well as for studying the broader role of those modulators in erythroid maturation.

SUBMITTER: Getman M

PROVIDER: S-EPMC6176860 | biostudies-other | 2014 Jul

REPOSITORIES: biostudies-other

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Extensively self-renewing erythroblasts derived from transgenic β-yac mice is a novel model system for studying globin switching and erythroid maturation.

Getman Michael M England Samantha J SJ Malik Jeffery J Peterson Kenneth K Palis James J Steiner Laurie A LA

Experimental hematology 20140402 7

Globin gene regulation occurs in the context of a maturing erythroid cell, which is undergoing significant changes in chromatin structure and gene expression. There are few model systems available that facilitate studies of globin gene regulation in the context of erythroid maturation. Extensively self-renewing erythroblasts (ESREs) are a nontransformed model of erythroid maturation derived from murine fetal liver or yolk sac. Imaging flow cytometry and RNA-seq studies demonstrate that ESREs fun ...[more]

PMID: 24704162

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Project description:The fetal and adult globin genes in the human ?-globin cluster on chromosome 11 are sequentially expressed to achieve normal hemoglobin switching during human development. The pharmacological induction of fetal ?-globin (HBG) to replace abnormal adult sickle ?S-globin is a successful strategy to treat sickle cell disease; however the molecular mechanism of ?-gene silencing after birth is not fully understood. Therefore, we performed global gene expression profiling using primary erythroid progenitors grown from human peripheral blood mononuclear cells to characterize gene expression patterns during the ?-globin to ?-globin (?/?) switch observed throughout in vitro erythroid differentiation.We confirmed erythroid maturation in our culture system using cell morphologic features defined by Giemsa staining and the ?/?-globin switch by reverse transcription-quantitative PCR (RT-qPCR) analysis. We observed maximal ?-globin expression at day 7 with a switch to a predominance of ?-globin expression by day 28 and the ?/?-globin switch occurred around day 21. Expression patterns for transcription factors including GATA1, GATA2, KLF1 and NFE2 confirmed our system produced the expected pattern of expression based on the known function of these factors in globin gene regulation. Subsequent gene expression profiling was performed with RNA isolated from progenitors harvested at day 7, 14, 21, and 28 in culture. Three major gene profiles were generated by Principal Component Analysis (PCA). For profile-1 genes, where expression decreased from day 7 to day 28, we identified 2,102 genes down-regulated > 1.5-fold. Ingenuity pathway analysis (IPA) for profile-1 genes demonstrated involvement of the Cdc42, phospholipase C, NF-K?, Interleukin-4, and p38 mitogen activated protein kinase (MAPK) signaling pathways. Transcription factors known to be involved in ?-and ?-globin regulation were identified.The same approach was used to generate profile-2 genes where expression was up-regulated over 28 days in culture. IPA for the 2,437 genes with > 1.5-fold induction identified the mitotic roles of polo-like kinase, aryl hydrocarbon receptor, cell cycle control, and ATM (Ataxia Telangiectasia Mutated Protein) signaling pathways; transcription factors identified included KLF1, GATA1 and NFE2 among others. Finally, profile-3 was generated from 1,579 genes with maximal expression at day 21, around the time of the ?/?-globin switch. IPA identified associations with cell cycle control, ATM, and aryl hydrocarbon receptor signaling pathways.The transcriptome analysis completed with erythroid progenitors grown in vitro identified groups of genes with distinct expression profiles, which function in metabolic pathways associated with cell survival, hematopoiesis, blood cells activation, and inflammatory responses. This study represents the first report of a transcriptome analysis in human primary erythroid progenitors to identify transcription factors involved in hemoglobin switching. Our results also demonstrate that the in vitro liquid culture system is an excellent model to define mechanisms of global gene expression and the DNA-binding protein and signaling pathways involved in globin gene regulation.

Project description:The fetal and adult globin genes in the human b-globin cluster on chromosome 11 are sequentially expressed to achieve normal hemoglobin switching during human development. The pharmacological induction of fetal g-globin (HBG) to replace abnormal adult sickle bS-globin is a successful strategy to treat sickle cell disease; however the molecular mechanism of g-gene silencing after birth is not fully understood. Therefore, we performed global gene expression profiling using primary erythroid progenitors grown from human peripheral blood mononuclear cells to characterize protein expression patterns during the g-globin to b-globin (g/b) switch observed throughout in vitro erythroid differentiation. We confirmed erythroid maturation in our culture system using cell morphologic features defined by Giemsa staining and the g/b-globin switch by reverse transcription-quantitative PCR (RT-qPCR) analysis. We observed maximal g-globin expression at day 7 with a switch to a predominance of b-globin expression by day 28 and the g/b-globin switch occurred around day 21. Expression patterns for transcription factors including GATA1, GATA2, KLF1 and NFE2 confirmed our system produced the expected pattern of expression based on the known function of these factors in globin gene regulation. Subsequent gene expression profiling was performed with RNA isolated from progenitors harvested at day 7, 14, 21, and 28 in culture. Three major gene profiles were generated by Principal Component Analysis (PCA). For profile-1 genes, where expression decreased from day 7 to day 28, we identified 2,102 genes down-regulated >1.5-fold. Ingenuity pathway analysis (IPA) for profile-1 genes demonstrated involvement of the Cdc42, phospholipase C, NF-Kb, Interleukin-4, and p38 mitogen activated protein kinase (MAPK) signaling pathways. Transcription factors known to be involved in g-and b-globin regulation were identified. The transcriptome analysis completed with erythroid progenitors grown in vitro identified groups of genes with distinct expression profiles, which function in metabolic pathways associated with cell survival, hematopoiesis, blood cells activation, and inflammatory responses. This study represents the first report of a transcriptome analysis in human primary erythroid progenitors to identify transcription factors involved in hemoglobin switching. Our results also demonstrate that the in vitro liquid culture system is a good model to define mechanisms of global gene expression and the DNA-binding protein and signaling pathways involved in globin gene regulation. Peripheral blood mononuclear cells were isolated from three normal donors using Histapaque-1.077. The mononuclear cells were grown in three independent cultures using the one-phase protocol as previously published. Cells were cultured in alphaMEM containing 30% fetal bovine serum, 1% deionized BSA with penicillin (100 U/mL) and streptomycin (0.1 mg/mL) at 37°C and 5% CO2. The following growth factors were added on day 0: stem cell factor (50 ng/mL), interleukin-3 (10 ng/mL) and erythropoietin (4 U/mL). Approximately 1.5 million cells were harvested from each culture (triplicate samples) on day 7, 14, 21 and 28 for microarray analysis on the whole-genome Illumina HumanWG-6 V2 Expression BeadChip.

Dataset Information

Extensively self-renewing erythroblasts derived from transgenic ?-yac mice is a novel model system for studying globin switching and erythroid maturation.

Publications

Extensively self-renewing erythroblasts derived from transgenic β-yac mice is a novel model system for studying globin switching and erythroid maturation.

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