A novel role for Lyl1 in primitive erythropoiesis
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE103789 | GEO | 2018/08/13
REPOSITORIES: GEO
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Project description:The Stem Cell Leukemia (Scl or Tal1) protein forms part of a multimeric transcription factor complex required for normal megakaryopoiesis. However, unlike other members of this complex such as Gata1, Fli1 and Runx1, mutations of Scl have not been observed as a cause of inherited thrombocytopenia. We postulated that functional redundancy with its closely related family member, Lymphoblastic Leukemia 1 (Lyl1) might explain this observation. To determine if Lyl1 can substitute for Scl in megakaryopoiesis, we examined the platelet phenotype of mice lacking one or both factors in megakaryocytes. Conditional Scl knockout mice crossed with transgenic mice expressing Cre recombinase under the control of the mouse platelet factor 4 (Pf4) promoter generated megakaryocytes with markedly reduced but not absent Scl. These Pf4SclcKO mice had mild thrombocytopenia and subtle defects in platelet aggregation. However, Pf4SclcKO mice generated on a Lyl1-null background (double knockout, DKO mice) had severe macrothrombocytopenia, abnormal megakaryocyte morphology, defective pro-platelet formation and markedly impaired platelet aggregation. DKO megakaryocytes, but not single knockouts, had reduced expression of Gata1, Fli1, Nfe2 and many other genes that cause inherited thrombocytopenia. These gene expression changes were significantly associated with shared Scl and Lyl1 E-box binding sites that were also enriched for Gata1, Ets and Runx1 motifs. Thus, Scl and Lyl1 share functional roles in platelet production and function by regulating expression of partner proteins including Gata1 and Fli1. We propose that this functional redundancy provides one explanation for the absence of Scl and Lyl1 mutations as a cause of inherited thrombocytopenia.
2020-12-21 | GSE125025 | GEO
Project description:Coordination of cellular processes through the establishment of tissue-specific gene expression programmes is essential for lineage maturation. The basic helix-loop-helix haemopoietic transcriptional regulator SCL/Tal1 is required for terminal differentiation of red blood cells. To gain insight into SCL function and mechanisms of action in erythropoiesis, we performed ChIP-sequencing and gene expression analyses from primary fetal liver erythroid cells. We show that SCL coordinates expression of genes in most known red cell-specific processes. The majority of SCLâs genomic targets require direct DNA-binding activity. However, one fifth of SCLâs target sequences, mainly amongst those showing high affinity for SCL, can recruit the factor independently of its DNA binding activity. An unbiased DNA motif search of sequences bound by SCL identified CAGNTG as SCL-preferred E-box motif in erythroid cells. Novel motifs were also characterised that may help distinguish activated from repressed genes and suggest a new mechanism by which SCL may be recruited to DNA. Finally, analysis of recruitment of GATA1, a protein partner of SCL, to sequences occupied by SCL suggests that SCLâs binding is necessary prior or simultaneous to that of GATA1. This work provides the framework to study regulatory networks leading to erythroid terminal maturation and to model mechanisms of action of tissue-specific transcription factors. Total RNA extracted from wild-type (WT) day E12.5 fetal liver Ter119- erythroid progenitor cells was compared to total RNA extracted from E12.5 fetal liver Ter119- cells expressing a DNA-binding mutant form of SCL (SclRER/RER).
2010-05-27 | E-GEOD-21877 | biostudies-arrayexpress
Project description:Coordination of cellular processes through the establishment of tissue-specific gene expression programmes is essential for lineage maturation. The basic helix-loop-helix haemopoietic transcriptional regulator SCL/Tal1 is required for terminal differentiation of red blood cells. To gain insight into SCL function and mechanisms of action in erythropoiesis, we performed ChIP-sequencing and gene expression analyses from primary fetal liver erythroid cells. We show that SCL coordinates expression of genes in most known red cell-specific processes. The majority of SCL’s genomic targets require direct DNA-binding activity. However, one fifth of SCL’s target sequences, mainly amongst those showing high affinity for SCL, can recruit the factor independently of its DNA binding activity. An unbiased DNA motif search of sequences bound by SCL identified CAGNTG as SCL-preferred E-box motif in erythroid cells. Novel motifs were also characterised that may help distinguish activated from repressed genes and suggest a new mechanism by which SCL may be recruited to DNA. Finally, analysis of recruitment of GATA1, a protein partner of SCL, to sequences occupied by SCL suggests that SCL’s binding is necessary prior or simultaneous to that of GATA1. This work provides the framework to study regulatory networks leading to erythroid terminal maturation and to model mechanisms of action of tissue-specific transcription factors.
2010-05-18 | GSE21877 | GEO
Project description:Primitive erythropoiesis in the mouse yolk sac is followed by definitive erythropoiesis resulting in adult erythrocytes. In comparison to definitive erythropoiesis little is known about the genes that control the embryonic erythroid program. The purpose of this study was to generate a profile of mouse embryonic yolk sac erythroid cells and identify novel regulatory genes differentially expressed in erythroid compared to non-erythroid (epithelial cells). The identification of these genes will contribute to a greater understanding of how the primitive erythroid program is controlled. This work will have clinical implications for treating sickle cell anemia and β-thalassemia. Activating genes in adult erythroid cells that increase embryonic or fetal globin gene expression may be a therapeutic approach to treat individuals with these disorders. Experiment Overall Design: Embryonic day 9.5 (E9.5) yolk sacs were dissected from the embryos of timed-pregnant FVB/N mice. These tissues were frozen in OCT media and 8-micron frozen sections were obtained. Laser capture microdissection (LCM) was used to isolate primitive erythroid precursors and epithelial cells from these E9.5 yolk sac frozen sections using 2 to 4 yolk sacs from 2 different litters per biological replicate. Paired erythroid and epithelial samples were collected from the same microscope slides. Total RNA was isolated from 4 different pairs of erythroid and epithelial samples and hybridized to Affymetrix 430 A 2.0 microarrays.
2008-06-11 | E-GEOD-10002 | biostudies-arrayexpress
Project description:The Krüppel-like factors, KLF1 and KLF2, positively regulate embryonic β-globin expression, and have additional overlapping roles in embryonic (primitive) erythropoiesis. KLF1-/-KLF2-/- double knockout mice are anemic at embryonic day 10.5 (E10.5) and die by E11.5, in contrast to single knockouts. To investigate the combined roles of KLF1 and KLF2 in primitive erythropoiesis, expression profiling of E9.5 erythroid cells was performed. A limited number of genes had a significantly decreasing trend of expression in wild-type, KLF1-/- and KLF1-/-KLF2-/-. Among these, c-myc emerged as a central node in the most significant gene network. c-myc expression is synergistically regulated by KLF1 and KLF2, and both factors bind the c-myc promoters. To characterize the role of c-myc in primitive erythropoiesis, ablation was performed specifically in mouse embryonic proerythroblast cells. After E9.5, these embryos exhibit an arrest in the normal expansion of circulating red cells and develop anemia analogous to KLF1-/-KLF2-/-. In the absence of c-myc, circulating erythroid cells do not show the normal increase in α- and β-like globin expression, but interestingly, have accelerated erythroid maturation, between E9.5 and E11.5. This study reveals a novel regulatory network by which KLF1 and KLF2 regulate c-myc, to control the primitive erythropoietic program. Timed-pregnant KLF1+/-, KLF1+/- KLF2+/- females were anesthetized and sacrificed. E9.5 yolk sacs were dissected from the embryo, cryoprotected in 20% sucrose in PBS and frozen in OCT media. A small portion of the embryo tail was used for PCR genotyping. Eight micron frozen yolk sac sections were obtained and laser capture microdissection (LCM) was used to isolate primitive erythroid precursors. For each biological replicate, 2 to 4 yolk sacs from 2 different litters were used. Total RNA was isolated from 8 different wild-type, 3 KLF1-/-, 3 KLF1-/- KLF2-/- erythroid samples and hybridized to Affymetrix 430 A 2.0 microarrays.
2012-03-12 | E-GEOD-36427 | biostudies-arrayexpress
Project description:The Krüppel-like factors, KLF1 and KLF2, positively regulate embryonic β-globin expression, and have additional overlapping roles in embryonic (primitive) erythropoiesis. KLF1-/-KLF2-/- double knockout mice are anemic at embryonic day 10.5 (E10.5) and die by E11.5, in contrast to single knockouts. To investigate the combined roles of KLF1 and KLF2 in primitive erythropoiesis, expression profiling of E9.5 erythroid cells was performed. A limited number of genes had a significantly decreasing trend of expression in wild-type, KLF1-/- and KLF1-/-KLF2-/-. Among these, c-myc emerged as a central node in the most significant gene network. c-myc expression is synergistically regulated by KLF1 and KLF2, and both factors bind the c-myc promoters. To characterize the role of c-myc in primitive erythropoiesis, ablation was performed specifically in mouse embryonic proerythroblast cells. After E9.5, these embryos exhibit an arrest in the normal expansion of circulating red cells and develop anemia analogous to KLF1-/-KLF2-/-. In the absence of c-myc, circulating erythroid cells do not show the normal increase in α- and β-like globin expression, but interestingly, have accelerated erythroid maturation, between E9.5 and E11.5. This study reveals a novel regulatory network by which KLF1 and KLF2 regulate c-myc, to control the primitive erythropoietic program.
2012-03-12 | GSE36427 | GEO
Project description:We used ChIP-Seq to map Ldb1, Scl and Gata1 binding sites in mouse total bone marrow cells. Together with functional studies comparing gene expression in Murine Erythroleukemia (MEL) cells expressing Ldb1 shRNA or control shRNA and bioinformatics analysis, we systematically determined the transcriptional program controlled by Ldb1 complexes in erythropoiesis. This represents the ChIP-Seq component of the study only To evaluate the role of Ldb1complexes in erythroid gene activation
2013-04-29 | E-GEOD-42843 | biostudies-arrayexpress
Project description:SCL/TAL1, a tissue-specific transcription factor of the basic helix-loop-helix (bHLH) family, and c-Kit, a tyrosine kinase receptor, control hematopoietic stem cell survival and quiescence. Here we report that SCL and c-Kit signaling control a common gene expression signature, of which 19 genes are associated with apoptosis. In vivo, SCL levels are limiting for the clonal expansion of Kit+ multipotent and erythroid progenitors. In addition, increased SCL expression specifically enhances the sensitivity of multipotent and megakaryocyte/erythroid progenitors to Steel factor (KIT ligand), whilst a DNA binding mutant antagonizes KIT function and induces apoptosis in progenitors. We conclude that Scl operates downstream of Kit to support the survival of megakaryocyte/erythroid progenitors. Finally, higher SCL expression upregulates Kit in normal bone marrow cells and increases chimerism after bone marrow transplantation, indicating that Scl is also upstream of Kit. We conclude that Scl and Kit establish a positive feedback loop in multipotent and megakaryocyte/erythroid progenitors.
2013-07-06 | GSE48557 | GEO
Project description:SCL/TAL1, a tissue-specific transcription factor of the basic helix-loop-helix (bHLH) family, and c-Kit, a tyrosine kinase receptor, control hematopoietic stem cell survival and quiescence. Here we report that SCL and c-Kit signaling control a common gene expression signature, of which 19 genes are associated with apoptosis. In vivo, SCL levels are limiting for the clonal expansion of Kit+ multipotent and erythroid progenitors. In addition, increased SCL expression specifically enhances the sensitivity of multipotent and megakaryocyte/erythroid progenitors to Steel factor (KIT ligand), whilst a DNA binding mutant antagonizes KIT function and induces apoptosis in progenitors. We conclude that Scl operates downstream of Kit to support the survival of megakaryocyte/erythroid progenitors. Finally, higher SCL expression upregulates Kit in normal bone marrow cells and increases chimerism after bone marrow transplantation, indicating that Scl is also upstream of Kit. We conclude that Scl and Kit establish a positive feedback loop in multipotent and megakaryocyte/erythroid progenitors. c-Kit regulated genes were extrapolated from gene expression profiles of TF-1 erythroid progenitor cells (empty MSCV vector) stimulated with SF (Kit ligand), Epo or GM-CSF. Second, SCL-regulated genes were obtained by expressing a DNA binding-defective SCL mutant (DbSCL) and selecting genes that were differentially expressed in M-oM-^AM-^DbSCL cells versus control cells (MSCV) stimulated with the same cytokines.
2013-07-06 | E-GEOD-48557 | biostudies-arrayexpress
Project description:Human erythropoiesis is a stepwise process in which multipotent hematopoietic stem/progenitor cells (HSPC) are initially committed towards the erythroid lineage and then differentiated into mature erythroid precursors. Commitment and differentiation are tightly regulated by the coordinated action of a host of transcription factors, including GATA2 and GATA1. Although the role of GATA factors in erythropoiesis has been extensively studied, how they regulate transcription from early to late stages of human erythropoiesis still remains underinvestigated. Here, we investigated GATA-mediated transcriptional regulation along erythroid development through the integrative analysis of gene expression, chromatin modifications, and GATA factors’ binding in human HSPC, early erythroid progenitors, and late precursors. A progressive loss of H3K27 acetylation, a mark of active regulatory elements, and diminished usage of active enhancers and super-enhancers was observed during erythroid lineage commitment and differentiation. We found that GATA factors mediate the transcriptional changes occurring during erythropoiesis through a stage-specific interplay with regulatory elements. In particular, GATA1 binds different sets of regulatory elements in early progenitors and late precursors, and controls the transcription of distinct genes in commitment and differentiation. By Chromosome Conformation Capture and CRISPR/Cas9-mediated genome editing, we demonstrated that the binding of GATA1 to a stage-specific super-enhancer sustains the expression of the stem cell factor receptor KIT in human erythroid progenitors. This study provides insights into the dynamics of epigenetic and transcriptional interactions during erythroid development and highlights a new layer of GATA1-mediated regulation in erythropoiesis.
2020-04-10 | GSE124163 | GEO