Project description:WNT signaling inhibition at an intermediate stage of differentiation is a key requirement for cardiac induction of human ES cells, suggesting that endogenous WNT activity interferes with cardiomyocyte formation. Two downstream genes of endogenous WNT signaling, MSX1 and CDX2, were induced during cardiac differentiation to reveal whether they may account for the global negative effects played by endogenous WNT signaling in this process.
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:In vitro cardiac differentiation of human ESCs recapitulates in vivo embryonic heart development, and thus, serves as an excellent tool to investigate human cardiac development. Identification of molecular signatures during cardiac differentiation of human ESCs is instrumental for advancing our understanding of human cardiogenesis. We, as well as others have improved cardiac differentiation protocols significantly in recent years; however, detailed molecular mechanisms involved in cardiac lineage commitment have not yet been clearly defined. Based on this, we tried to identify the cellular hierarchies and molecular signatures of each of the in vitro human ESC-differentiating cardiac cell lineages through the well-established cardiac differentiatio protocol by Wnt signaling modulation and the FACS-sorted population RNA-seq analyses.
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.
Project description:Embryonic stem (ES) cells have the potential to generate a variety of cell lineages including endothelial cells, blood cells and smooth muscle cells. flk1-expressing cells derived from ES cells serve as vascular progenitors. We have used global gene expression analysis in order to establish a comprehensive list of candidate genes in the developing vasculature during ES cell differentiation in vitro. A large set of genes, including growth factors, cell surface molecules, transcriptional factors, and members of several signal transduction pathways that are known to be involved in vasculogenesis or angiogenesis, were found to have expression patterns as expected. Some unknown or functionally uncharacterized genes were differentially regulated in flk1+ cells compared with flk1 cells, suggesting possible roles for these genes in vascular commitment. Particularly, multiple components of the Wnt signaling pathway were differentially regulated in flk1+ cells, including Wnt proteins, their receptors, downstream transcriptional factors, and other components belonging to this pathway. Activation of the Wnt signal was able to expand vascular progenitor populations whereas suppression of Wnt activity reduced flk1+ populations. Suppression of Wnt signaling also inhibited the formation of matured vascular capillary-like structures during late stages of EB differentiation. These data indicate a requisite and ongoing role for Wnt activity during vascular development, and the gene expression profiles identify candidate components of this pathway that participate in vascular cell differentiation. Keywords: Time course, development, endothelial cell, angiogenesis, embryonic stem cells, mouse, vasculature, Wnt signaling
Project description:Embryonic signaling pathways exert stage-specific effects during cardiac development, yet the precise cues for proliferation or maturation remain elusive. To address this, we utilized spontaneously beating human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) at day 12 of differentiation and performed a combinatory screen for various dosages of the glycogen synthase kinase-3 (GSK3) inhibitor CHIR99021 and Insulin for the analysis of cell cycle in hiPSC-CMs. Our combinatory screen for proliferation, subsequential downstream sarcomere development and RNA-seq analyses for Insulin/Akt and CHIR99021/Wnt demonstrate synergistic effects on proliferation of immature hiPSC-CMs. Conversely, removal of the Wnt and Insulin stimuli leads to rapid cell cycle exit and facilitates the terminal differentiation of immature hiPSC-CMs. Detailed characterization reveals that Wnt/CHIR99021, but not Insulin, regulates sarcomere homeostasis and architecture of immature hiPSC-CMs. Moreover, we further identify a temporal interplay between CHIR99021/Wnt via TCF and Insulin via FoxO signaling as regulators between proliferation and maturation in immature hiPSC-CMs. This work describes the cues that control proliferation versus terminal differentiation in functional immature hiPSC-CMs, and provides molecular mechanistic understanding between proliferation and maturation development of hiPSC-CMs.
Project description:Cardiovascular diseases are a major cause of life-threatening burden around the world. The heart has a very low regeneration capacity and donor organs for transplantation are scarce. Therefore regeneration of lost myocardium with stem cell-derived cardiomyocytes (CMs) provides an attractive strategy for heart repair. Human pluripotent stem cells (hPSCs) can be efficiently differentiated in vitro into CMs but the molecular mechanisms behind this process are still not fully understood. In particular identification of secreted autocrine and/or paracrine factors that function as important extrinsic signals remained elusive because the mass spectrometry (MS)-based identification of secreted proteins from cell culture supernatants is impeded by high levels of albumin present in common differentiation media. Thus we established an albumin-free cardiomyogenic differentiation medium and performed secretomics at seven different time points during in vitro differentiation. This analysis led to the identification of 4832 proteins with 1802 being significantly altered during differentiation and 431 of these were annotated as secreted according to gene ontology. Bioinformatics revealed enrichment of extrinsic Wnt pathway-related proteins 3 days upon induction of differentiation and of extracellular matrix proteins in the resulting CMs. Numerous extrinsic components of Wnt, Activin A, Nodal, TGFβ, BMP or FGF signaling pathways were quantitatively assessed during differentiation. Notably, the abundance of pathway agonists was generally lower compared to the respective antagonists but their curves of progression over timer were rather similar. We hypothesize that Activin A, Nodal and TGFβ signaling are turned down shortly upon initiation of cardiac differentiation whereas BMP signaling is switched on. Wnt and FGF signaling peaks between d0 and d3 of differentiation and interestingly, Activin A and TGFβ signaling seem to be reactivated at the cardiac progenitor stages and/or in early CMs.
Project description:A simultaneous stimulation of the Activin / FGF, BMP, and WNT pathways is required for promoting most efficient mesoderm induction in human embryonic stem cells, as well as for subsequent differentiation into cardiomyocytes. To reveal the contributions of three of these signaling pathways to mesoderm formation and cardiac induction, comparative differentiation time-courses were recorded, varying the combinations of signaling factors administered to the cells during the first day of differentiation: FGF (F) + BMP (B) + WNT (W) treatment during the first 24 hours, or FGF + BMP, or BMP + WNT, or FGF + WNT
Project description:Human ES cells were induced to differentiate using a directed cardiac induction protcol but varying the concentrations of BMP4 and WNT (CHIR00921) applied during the first 24 hours. The resulting differences in cell fate were then analyzed two weeks later.
Project description:Background: Ion channels are key determinants for the function of excitable cells but little is known about their role and involvement during cardiac development. Earlier work identified Ca2+-activated potassium channels of small and intermediate conductance (SKCas) as important regulators of neural stem cell fate. Here, we have investigated their impact on the differentiation of pluripotent cells towards the cardiac lineage. Methods and Results: We have applied the SKCa-activator EBIO on embryonic stem cells and identified this particular ion channel family as a new critical target involved in the generation of cardiac pacemaker-like cells: SKCa-activation led to rapid remodeling of the actin cytoskeleton, inhibition of proliferation, induction of differentiation and diminished teratoma formation. Time-restricted SKCa-activation induced cardiac mesoderm and commitment to the cardiac lineage as shown by gene regulation, protein and functional electrophysiological studies. In addition, the differentiation into cardiomyocytes was modulated in a qualitative fashion, resulting in a strong enrichment of pacemaker-like cells. This was accompanied by induction of the sino-atrial gene program and in parallel by a loss of the chamber-specific myocardium. In addition, SKCa activity induced activation of the Ras-Mek-Erk signaling cascade, a signaling pathway involved in the EBIO-induced effects. Conclusions: SKCa-activation drives the fate of pluripotent cells towards the cardiac lineage and preferentially into pacemaker-like cardiomyocytes. This provides a novel strategy for the enrichment of cardiomyocytes and in particular, the generation of a specific subtype of cardiomyocytes, pacemaker-like cells, without genetic modification. Untreated ES cells in three independent experiments: - Untreated control ES cells sample 1 (Con_1) - Untreated control ES cells sample 2 (Con_2) - Untreated control ES cells sample 3 (Con_3) EBIO-treated ES cells in three independent experiments: - EBIO-treated ES cells sample 1 (EBIO_1) - EBIO-treated ES cells sample 2 (EBIO_2) - EBIO-treated ES cells sample 3 (EBIO_3) Untreated differentiated ES cells in two independent experiments: - Untreated control differentiated ES cells sample 1 (Con_day5+10_1) - Untreated control differentiated ES cells sample 2 (Con_day5+10_2) EBIO-treated differentiated ES cells in two independent experiments: - EBIO-treated differentiated ES cells sample 1 (EBIO_day5+10_1) - EBIO-treated differentiated ES cells sample 2 (EBIO_day5+10_2)