Early lineage restriction and regional segregation during mammalian heart development
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ABSTRACT: Cardiac development arises from two sources of mesoderm progenitors, the first (FHF) and the second heart field (SHF). Mesp1 has been proposed to mark the most primitive multipotent cardiac progenitors common for both heart fields. Here, using clonal analysis of the earliest prospective cardiovascular progenitors in a temporally controlled manner during the early gastrulation, we found that Mesp1 progenitors consist of two temporally distinct pools of progenitors restricted to either the FHF or the SHF. FHF progenitors were unipotent, while SHF progenitors, were either uni- or bipotent. Microarray and single cell RT-PCR analysis of Mesp1 progenitors revealed the existence of molecularly distinct populations of Mesp1 progenitors, consistent with their lineage and regional contribution. Altogether, these results provide evidence that heart development arises from distinct populations of unipotent and bipotent cardiac progenitors that independently express Mesp1 at different time points during their specification, revealing that the regional segregation and lineage restriction of cardiac progenitors occurs very early during gastrulation. We used microarrays to characterize the molecular mechanisms that control Mesp1 progenitor specification and lineage segregation during the early stage of cardiac mesoderm formation, 50 Mesp1 H2B-GFP+ or Mesp1 H2B-GFP- cells at E6.5 or E7.5 from mouse embryos were sorted for RNA extraction, amplification and hybridization on Affimetrix microarrays. Microaarrays were performed on Mouse Genome 430 PM strip Affymetrix array. The overall design was repeated in two different biological samples.
Project description:Cardiac development arises from two sources of mesoderm progenitors, the first (FHF) and the second heart field (SHF). Mesp1 has been proposed to mark the most primitive multipotent cardiac progenitors common for both heart fields. Here, using clonal analysis of the earliest prospective cardiovascular progenitors in a temporally controlled manner during the early gastrulation, we found that Mesp1 progenitors consist of two temporally distinct pools of progenitors restricted to either the FHF or the SHF. FHF progenitors were unipotent, while SHF progenitors, were either uni- or bipotent. Microarray and single cell RT-PCR analysis of Mesp1 progenitors revealed the existence of molecularly distinct populations of Mesp1 progenitors, consistent with their lineage and regional contribution. Altogether, these results provide evidence that heart development arises from distinct populations of unipotent and bipotent cardiac progenitors that independently express Mesp1 at different time points during their specification, revealing that the regional segregation and lineage restriction of cardiac progenitors occurs very early during gastrulation. We used microarrays to characterize the molecular mechanisms that control Mesp1 progenitor specification and lineage segregation during the early stage of cardiac mesoderm formation,
Project description:A hESC MESP1-MCHERRY reporter line was used to isolate and study the molecular character of MESP1 expressing pre-cardiac progenitors, derived from hESC. MESP1 is a key-transcription factor for pre-cardiac mesoderm and is marking the progenitor for almost all cells of the heart. This reporter line was used to study cardiac differentiation and the derivation of early cardiac progenitors in vitro. hESCs were differentiated towards the cardiac lineage, expressing MESP1-mCherry at day 3 of differentiation. Total RNA obtained from isolated MESP1-mCherry expressing progenitors was compared to that of non-MESP1-expressing progenitors and undifferentiated hESCs in order to characterize MESP1-specific transcription factors and proteins.
Project description:Progenitor cells of the first and second heart fields (FHF and SHF) depend on cardiac-specific transcription factors for their differentiation. In mouse mutant embryos, we define the hierarchy of signaling events that controls the expression of cardiac-specific transcription factors during commitment of SHF progenitors at E9.25. Wnt and Bmp act downstream of Notch/RBPJ at this developmental stage. Mutation of Axin2, the negative regulator of canonical Wnt signaling, enhances Wnt and Bmp signals and suffices to rescue the cardiac differentiation arrest caused by loss of RBPJ. By analysis of isolated cardiac progenitors, embryo cultures in the presence of pharmacological inhibitors, and Bmp triple mutants, we could classify the expression of heart-specific transcription factors of SHF progenitors according to their dependence on either Wnt or Bmp signals, Nkx2-5, Isl1, Baf60c and Gata4, SRF, Mef2c, respectively. Total RNA from whole embryonic hearts of control mice was compared to MesP1-cre:RBPJlox/lox (KO), MesP1-cre:RBPJlox/lox//Axin2-/- (DKO), MesP1-cre:RBPJlox/+//Axin2-/- (hetDKO) and MesP1-cre:RBPJlox/lox//Axin2+/- (DKOhet) mutant mouse embryos.
Project description:Mouse heart development arises fromMesp1 expressing cardiovascular progenitors that are specified at the early stage of gastrulation. Lineage tracing and clonal analysisof Mesp1 progenitors revealed that heart development arises from distinct populations of Mesp1+ cardiovascular progenitors (CPs) expressing Mesp1 at different time points during gastrulation that contribute to different heart regions and different cardiovascular lineages. However, it remains unclear what are the molecular mechanisms that control the early regional and lineage segregation of Mesp1 CPs. Here, we performedsingle cell RNA-sequencing of FACS isolated Mesp1 CPs in WT and Mesp1 null embryos at different times to define the cellular and molecular heterogeneity of the Mesp1CPs, identify the role of Mesp1 in regulating cellular heterogeneity and uncover the mechanisms associated with lineage and regional segregation during the early stages of gastrulation.We showed that Mesp1 CPs isolated at E6.75 and E7.25 are molecularly distinct and make the continuum betweenepiblast and later mesodermal cells including hematopoietic progenitors. Single cell transcriptome of Mesp1 deficient CPsshowed that Mesp1 is required for the exitof thepluripotent state and the induction of the cardiovascular gene expression program in vivo.Using dimensional reduction analysis, we identified distinct populations of Mesp1 CPs that correspond to progenitors committed to different celllineages and regions of the heart, identifying the molecular features associated with the early lineage and regional segregation. Notch1CREER lineage tracing, a marker preferentially expressed by one of the different Mesp1CP subpopulations, during the early stage of gastrulation marked almost exclusively ECs, demonstrating theexistence of an early Mesp1 subpopulation committed to the EC fate.This study uncoversthe cellular and molecular heterogeneity associated with early lineage restriction and regional segregation of the heart at the early stage of gastrulation.
Project description:We have developed a protocol to generate cardiopharyngeal mesoderm (CPM) in vitro by Mesp1 induction in ES cells. The goal of this study is to compare the transcriptome of CPM-derived cardiac and skeletal myogenic progenitors to identify novel lineage-specific markers. mRNA profiles of CPM-derived D6 (early) and D12 (late), cardiac (BMP) and skeletal myogenic (control) progenitors were generated
Project description:We used single-cell RNA-seq to reconstruct differentiation paths of cardiac progenitors in two sequential waves during early heart development. Further analysis identified six major cell types and multiple differentiation trajectories of cardiac progenitors derived from distinct heart fields. We also constructed TF regulatory networks controlling SHF CPC differentiation. Interlineage crosstalk through signaling pathways and chemotactic guidance played a potent role in SHF CPC deployment. The mechanisms regulating SHF CPC migration and differentiation was further confirmed by Nkx2-5 CPC enhancer knock out. Our work provides a cardiac lineage hierarchy and new insights of SHF CPC development.
Project description:A hESC MESP1-MCHERRY reporter line was used to isolate and study the molecular character of MESP1 expressing pre-cardiac progenitors, derived from hESC. MESP1 is a key-transcription factor for pre-cardiac mesoderm and is marking the progenitor for almost all cells of the heart. This reporter line was used to study cardiac differentiation and the derivation of early cardiac progenitors in vitro.
Project description:We used single-cell RNA-seq to reconstruct differentiation paths of cardiac progenitors in two sequential waves during early heart development. Further analysis identified six major cell types and multiple differentiation trajectories of cardiac progenitors derived from distinct heart fields. We also constructed TF regulatory networks controlling SHF CPC differentiation. Interlineage crosstalk through signaling pathways and chemotactic guidance played a potent role in SHF CPC deployment. The mechanisms regulating SHF CPC migration and differentiation was further confirmed by Nkx2-5 enhancer knock out. Our work provides a cardiac lineage hierarchy and new insights into SHF CPC development. Mechanistically, NKX2-5 directly bound the Cxcr2 genomic locus and activated its transcription.
Project description:The mammalian heart arises from various populations of Mesp1-expressing cardiovascular progenitors (CPs) that are specified during the early stages of gastrulation. Mesp1 acts as a master regulator of CP specification and differentiation. However, how Mesp1 regulates the chromatin landscape of nascent mesodermal cells to define the temporal and spatial patterning of the distinct populations of CP remains unknown. Here, by combining ChIP-seq, RNA-seq and ATAC-seq during mouse pluripotent stem cell differentiation, we defined the temporal remodelling of the chromatin landscape mediated by Mesp1. We identified different enhancers that are temporally regulated to erase the pluripotent state and specify the pools of CPs that mediate heart development. We found that Mesp1 acts as a pioneer transcription factor (TF) and identified Zic TFs as essential cofactors that regulate Mesp1 pioneer activity at key mesodermal enhancers, thereby regulating the chromatin remodelling and gene expression associated with the specification of the different populations of CPs in vivo. Our study identifies the dynamics of the chromatin landscape and enhancer remodelling associated with temporal patterning of early mesodermal cells into the distinct populations of CPs that mediate heart development.
Project description:The mammalian heart arises from various populations of Mesp1-expressing cardiovascular progenitors (CPs) that are specified during the early stages of gastrulation. Mesp1 acts as a master regulator of CP specification and differentiation. However, how Mesp1 regulates the chromatin landscape of nascent mesodermal cells to define the temporal and spatial patterning of the distinct populations of CP remains unknown. Here, by combining ChIP-seq, RNA-seq and ATAC-seq during mouse pluripotent stem cell differentiation, we defined the temporal remodelling of the chromatin landscape mediated by Mesp1. We identified different enhancers that are temporally regulated to erase the pluripotent state and specify the pools of CPs that mediate heart development. We found that Mesp1 acts as a pioneer transcription factor (TF) and identified Zic TFs as essential cofactors that regulate Mesp1 pioneer activity at key mesodermal enhancers, thereby regulating the chromatin remodelling and gene expression associated with the specification of the different populations of CPs in vivo. Our study identifies the dynamics of the chromatin landscape and enhancer remodelling associated with temporal patterning of early mesodermal cells into the distinct populations of CPs that mediate heart development.