Project description:During development, lineage specification is controlled by several signaling pathways involving various transcription factors (TFs). Here, we studied the RE1-silencing transcription factor (REST) and identified an important role of this TF in cardiac differentiation. Using mouse embryonic stem cells (ESC) to model development, we analyzed the effect of REST knock-out on the ability to these cells to differentiate into the cardiac lineage. Detailed analysis of specific lineage markers expression showed selective down-regulation of endoderm markers in REST-null cells, thus contributing to a loss of cardiogenic signals. We propose here a new role for REST in cell fate specification besides its well-known repressive role of neuronal differentiation.
Project description:Alternative splicing is critical for development. However, its role in the specification of the three embryonic germ layers is poorly understood. By performing RNA-Seq on human embryonic stem cells (hESCs) and derived endoderm, cardiac mesoderm, and ectoderm cell lineages, we detect distinct alternative splicing programs associated with each lineage. The most prominent splicing program differences are observed between definitive endoderm and cardiac mesoderm. Integrative multi-omics analyses link each program with lineage-specific RNA binding protein regulators, and further suggest a widespread role for Quaking (QKI) in the specification of cardiac mesoderm. Remarkably, knockout of QKI disrupts the cardiac mesoderm-associated alternative splicing program and formation of myocytes. These changes likely arise in part through reduced expression of BIN1 splice variants linked to cardiac development. Collectively, our results thus uncover alternative splicing programs associated with the three germ lineages and demonstrate an important role for QKI in the formation of cardiac mesoderm.
Project description:ZNF462 haploinsufficiency is linked to Weiss-Kruszka Syndrome, a genetic disorder characterized by neurodevelopmental defects including Autism. Though conserved in vertebrates and essential for embryonic development the molecular functions of ZNF462 remain unclear. We identified its murine homolog ZFP462 in a screen for mediators of epigenetic gene silencing. Here, we show that ZFP462 safeguards neural lineage specification of mouse embryonic stem cells (ESCs) by targeting the H3K9-specific histone methyltransferase complex G9A/GLP to silence mesoendodermal genes. ZFP462 binds to transposable elements (TEs) that are potential enhancers harboring ESC-specific transcription factor (TF) binding sites. Recruiting G9A/GLP, ZFP462 seeds heterochromatin, restricting TF binding. Loss of ZFP462 in ESCs results in increased chromatin accessibility at target sites and ectopic expression of mesoendodermal genes. Taken together, ZFP462 confers lineage- and locus-specificity to the broadly expressed epigenetic regulator G9A/GLP. Our results suggest that aberrant activation of lineage non-specific genes in the neuronal lineage underlies ZNF462-associated neurodevelopmental pathology.
Project description:Several of the essential core transcriptional control elements in human embryonic stem cells (ESCs) have been identified, but the production and function of alternative isoforms in self-renewal, pluripotency and tissue lineage specification remain largely unknown. We have modified the H9 ESC line to allow for drug selection of human pluripotent ESCs and cardiac progenitors. Exon-level microarray expression data from undifferentiated ESCs and day 40 cardiac precursors were used to identify differentially expressed and alternative splice isoforms during differentiation. Keywords: comparison
Project description:Several of the essential core transcriptional control elements in human embryonic stem cells (ESCs) have been identified, but the production and function of alternative isoforms in self-renewal, pluripotency and tissue lineage specification remain largely unknown. We have modified the H9 ESC line to allow for drug selection of human pluripotent ESCs and cardiac progenitors. Exon-level microarray expression data from undifferentiated ESCs and day 40 cardiac precursors were used to identify differentially expressed and alternative splice isoforms during differentiation. Keywords: comparison RNA from a homogenous population of undifferentiated hESCs (REX1-neo promoter drug selection) and differentiated day 40 cardiomyocytes (alpha MHC-puro promoter drug selection) was isolated and profiled with exon-tiling arrays.
Project description:Study to investigate the role of histone residues H3K4 and H3K36 for gene expression, histone localization and neuronal lineage specification by mutation of K4 and K36 in H3.3 to alanine. Histone variant H3.3 differs from the canonical H3.1/H3.2 by only 4 to 5 amino acids, which are necessary for nucleosome assembly independent of DNA replication, and is encoded by two gene copies. Complete loss of the two H3.3 genes (H3f3a and H3f3b) leads to embryonic lethality while single gene knockout yields viable mice. We used CRISPR-Cas9 to delete H3f3a and introduce homozygous point-mutations into H3f3b, thus ensuring that the entire pool of H3.3 protein carries the mutation of interest. We differentiated H3.3ctrl (H3f3a knock-out; H3f3b wild type), H3.3K4A mutant (H3f3a knock-out; H3f3b K4A) and H3.3K36A mutant (H3f3a knock-out; H3f3b K36A) ESCs into glutamatergic neurons. Gene expression profiles were measured by mRNA-Sequencing in undifferentiated ESCs (D0), neurodevelopment (D8) and differentiated neurons (D12) to assess the impact of the mutation on gene expression and development.
Project description:Study to investigate the role of histone residues H3K4 and H3K36 for gene expression, histone localization and neuronal lineage specification by mutation of K4 and K36 in H3.3 to alanine. Histone variant H3.3 differs from the canonical H3.1/H3.2 by only 4 to 5 amino acids, which are necessary for nucleosome assembly independent of DNA replication, and is encoded by two gene copies. Complete loss of the two H3.3 genes (H3f3a and H3f3b) leads to embryonic lethality while single gene knockout yields viable mice. We used CRISPR-Cas9 to delete H3f3a and introduce homozygous point-mutations into H3f3b, thus ensuring that the entire pool of H3.3 protein carries the mutation of interest. We differentiated H3.3ctrl (H3f3a knock-out; H3f3b wild type), H3.3K4A mutant (H3f3a knock-out; H3f3b K4A) and H3.3K36A mutant (H3f3a knock-out; H3f3b K36A) ESCs into glutamatergic neurons. Genomic localization of H3.3 protein was determined by ChIP-Sequencing in ESCs (D0). Histone modifications patterns of H3K4me1, H3K4me3 and H3K27ac were measured by ChIP-Sequencing in ESCs (D0) to assess the impact of the H3.3K4A mutation on the epigenetic landscape. Levels of H3K36me3 were measured by ChIP-Sequencing in WT and H3.3K36A mutant ESCs (D0), NPCs (D8) and neurons (D12) to assess the impact of the H3.3K36A mutation on H3K36me3 levels in development.
Project description:In spite of lacking circadian rhythms, several master clock regulators are readily expressed in embryonic stem cells (ESCs). In particular, the role of Brain and Muscle ARNT-Like 1 (Bmal1, also known as Arntl) remains to be addressed. Here, we generated Bmal1 CRISPR/cas9 knock-out ESCs to elucidate the role of BMAL1 in pluripotency maintenance and differentiation. Our findings indicate that although BMAL1 is dispensable for ESC maintenance, it is required for proper differentiation. Moreover, we find that Bmal1 participates in the transcriptional regulation of lineage specification programs during differentiation and gastrulation in vitro. In particular, loss-of-function of Bmal1 changes the metabolic state of ESCs by promoting more oxidation at the expense of glycolysis. Our data points to a circadian clock-independent function of BMAL1 during early developmental stages, and will help in the understanding of the mechanisms that control exit from pluripotency and early cell-fate decisions.
Project description:Study to investigate the role of histone residues H3K4 and H3K36 for gene expression, histone localization and neuronal lineage specification by mutation of K4 and K36 in H3.3 to alanine. Histone variant H3.3 differs from the canonical H3.1/H3.2 by only 4 to 5 amino acids, which are necessary for nucleosome assembly independent of DNA replication, and is encoded by two gene copies. Complete loss of the two H3.3 genes (H3f3a and H3f3b) leads to embryonic lethality while single gene knockout yields viable mice. We used CRISPR-Cas9 to delete H3f3a and introduce homozygous point-mutations into H3f3b, thus ensuring that the entire pool of H3.3 protein carries the mutation of interest. We differentiated H3.3ctrl (H3f3a knock-out; H3f3b wild type), H3.3K4A mutant (H3f3a knock-out; H3f3b K4A) and H3.3K36A mutant (H3f3a knock-out; H3f3b K36A) ESCs into glutamatergic neurons. To assess the effect of the K4A mutation on Pol II activity, nascent RNA levels were mesaured by PRO-seq.
Project description:Study to investigate the role of histone residues H3K4 and H3K36 for gene expression, histone localization and neuronal lineage specification by mutation of K4 and K36 in H3.3 to alanine. Histone variant H3.3 differs from the canonical H3.1/H3.2 by only 4 to 5 amino acids, which are necessary for nucleosome assembly independent of DNA replication, and is encoded by two gene copies. Complete loss of the two H3.3 genes (H3f3a and H3f3b) leads to embryonic lethality while single gene knockout yields viable mice. We used CRISPR-Cas9 to delete H3f3a and introduce homozygous point-mutations into H3f3b, thus ensuring that the entire pool of H3.3 protein carries the mutation of interest. We differentiated H3.3ctrl (H3f3a knock-out; H3f3b wild type), H3.3K4A mutant (H3f3a knock-out; H3f3b K4A) and H3.3K36A mutant (H3f3a knock-out; H3f3b K36A) ESCs into glutamatergic neurons. Genomic localization of H3.3 protein was determined by ChIP-Sequencing in ESCs (D0). Distribution patterns of RNA Polymerase II Phosphorylated on Serine 5 (RNA Pol II Ser5P), of histone modification H3K27me3 and chromatin remodeler components Brg1/Smarca4 (Swi/Snf) and Chd4 (NuRD) were measured by ChIP-Sequencing in ESCs (D0) to assess the impact of the H3.3K4A mutation on the epigenetic landscape. Distribution patterns of H3.3 were assessed by ChIP-Sequencing in HEK293T cells after depletion of Brg1/Smarca4 (Swi/Snf) and Chd4 (NuRD).