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Nature Communications Jun 2024DNA replication in differentiated cells follows a defined program, but when and how it is established during mammalian development is not known. Here we show using...
DNA replication in differentiated cells follows a defined program, but when and how it is established during mammalian development is not known. Here we show using single-cell sequencing, that late replicating regions are established in association with the B compartment and the nuclear lamina from the first cell cycle after fertilization on both maternal and paternal genomes. Late replicating regions contain a relative paucity of active origins and few but long genes and low G/C content. In both bovine and mouse embryos, replication timing patterns are established prior to embryonic genome activation. Chromosome breaks, which form spontaneously in bovine embryos at sites concordant with human embryos, preferentially locate to late replicating regions. In mice, late replicating regions show enhanced fragility due to a sparsity of dormant origins that can be activated under conditions of replication stress. This pattern predisposes regions with long neuronal genes to fragility and genetic change prior to separation of soma and germ cell lineages. Our studies show that the segregation of early and late replicating regions is among the first layers of genome organization established after fertilization.
Topics: Animals; DNA Replication; Mice; Embryo, Mammalian; Cattle; Nuclear Lamina; Female; Male; Humans; Embryonic Development; Genome; Single-Cell Analysis
PubMed: 38898078
DOI: 10.1038/s41467-024-49565-7 -
Nature Communications Jun 2024Mutations in the FOXF1 gene, a key transcriptional regulator of pulmonary vascular development, cause Alveolar Capillary Dysplasia with Misalignment of Pulmonary Veins,...
Mutations in the FOXF1 gene, a key transcriptional regulator of pulmonary vascular development, cause Alveolar Capillary Dysplasia with Misalignment of Pulmonary Veins, a lethal lung disease affecting newborns and infants. Identification of new FOXF1 upstream regulatory elements is critical to explain why frequent non-coding FOXF1 deletions are linked to the disease. Herein, we use multiome single-nuclei RNA and ATAC sequencing of mouse and human patient lungs to identify four conserved endothelial and mesenchymal FOXF1 enhancers. We demonstrate that endothelial FOXF1 enhancers are autoactivated, whereas mesenchymal FOXF1 enhancers are regulated by EBF1 and GLI1. The cell-specificity of FOXF1 enhancers is validated by disrupting these enhancers in mouse embryonic stem cells using CRISPR/Cpf1 genome editing followed by lineage-tracing of mutant embryonic stem cells in mouse embryos using blastocyst complementation. This study resolves an important clinical question why frequent non-coding FOXF1 deletions that interfere with endothelial and mesenchymal enhancers can lead to the disease.
Topics: Forkhead Transcription Factors; Animals; Humans; Persistent Fetal Circulation Syndrome; Mice; Enhancer Elements, Genetic; Mesoderm; Lung; Endothelial Cells; Zinc Finger Protein GLI1; Embryonic Stem Cells; Pulmonary Alveoli
PubMed: 38898031
DOI: 10.1038/s41467-024-49477-6 -
Nature Communications Jun 2024Single-cell RNA sequencing (scRNA-seq) has been widely used to characterize cell types based on their average gene expression profiles. However, most studies do not...
Single-cell RNA sequencing (scRNA-seq) has been widely used to characterize cell types based on their average gene expression profiles. However, most studies do not consider cell type-specific variation across donors. Modelling this cell type-specific inter-individual variation could help elucidate cell type-specific biology and inform genes and cell types underlying complex traits. We therefore develop a new model to detect and quantify cell type-specific variation across individuals called CTMM (Cell Type-specific linear Mixed Model). We use extensive simulations to show that CTMM is powerful and unbiased in realistic settings. We also derive calibrated tests for cell type-specific interindividual variation, which is challenging given the modest sample sizes in scRNA-seq. We apply CTMM to scRNA-seq data from human induced pluripotent stem cells to characterize the transcriptomic variation across donors as cells differentiate into endoderm. We find that almost 100% of transcriptome-wide variability between donors is differentiation stage-specific. CTMM also identifies individual genes with statistically significant stage-specific variability across samples, including 85 genes that do not have significant stage-specific mean expression. Finally, we extend CTMM to partition interindividual covariance between stages, which recapitulates the overall differentiation trajectory. Overall, CTMM is a powerful tool to illuminate cell type-specific biology in scRNA-seq.
Topics: Humans; Single-Cell Analysis; Sequence Analysis, RNA; Induced Pluripotent Stem Cells; Transcriptome; Cell Differentiation; Gene Expression Profiling; RNA-Seq; Endoderm
PubMed: 38898015
DOI: 10.1038/s41467-024-49242-9 -
Stem Cell Research Jun 2024Here we present the generation of HIMRi006-A and HIMRi007-A Pompe disease (PD) patient derived human induced pluripotent stem cell (hiPSC) lines. HIMRi006-A represents...
Here we present the generation of HIMRi006-A and HIMRi007-A Pompe disease (PD) patient derived human induced pluripotent stem cell (hiPSC) lines. HIMRi006-A represents an infantile onset disease (IOPD) phenotype caused by a homozygous c.307 T > G mutation in the GAA gene. HIMRi007-A is characterized by heterozygous mutations c.-32-13 T > G/c.1716C > G and is associated with an adult onset of disease symptoms (LOPD). Both lines are generated via lentiviral expression of OCT4, SOX2, KLF4, and c-MYC. The lines display a typical embryonic stem cell morphology, express pluripotency markers, retain a normal karyotype (46, XX/XY) and have the differentiation capacity in all three germ layers. Altogether, both lines provide a resource tool to the community for future in depth molecular studies of PD pathomechanism.
PubMed: 38896971
DOI: 10.1016/j.scr.2024.103459 -
Stem Cell Research Jun 2024Calcium indicators are sensitive tools to image neural activity. However, their use in human induced pluripotent stem cells (iPSC)-derived neurons is limited by...
Calcium indicators are sensitive tools to image neural activity. However, their use in human induced pluripotent stem cells (iPSC)-derived neurons is limited by silencing of the transgene. We generated the iPSC line MSE2336A carrying heterozygous insertion in the safe-harbor locus AAVS1 of the ultrasensitive protein calcium sensor (GCaMP6) under the control of CAG promoter and UCOE to maintain robust transgene expression in differentiated cells. The iPSC exhibited normal cell morphology, expression of pluripotency markers, genome integrity, and the ability to differentiate into the three primary germ layers. This line provides a powerful model to study activity in human neurons.
PubMed: 38896969
DOI: 10.1016/j.scr.2024.103455 -
Heterochromatin protein ERH represses alternative cell fates during early mammalian differentiation.BioRxiv : the Preprint Server For... Jun 2024During development, H3K9me3 heterochromatin is dynamically rearranged, silencing repeat elements and protein coding genes to restrict cell identity. Enhancer of...
During development, H3K9me3 heterochromatin is dynamically rearranged, silencing repeat elements and protein coding genes to restrict cell identity. Enhancer of Rudimentary Homolog (ERH) is an evolutionarily conserved protein originally characterized in fission yeast and recently shown to be required for H3K9me3 maintenance in human fibroblasts, but its function during development remains unknown. Here, we show that ERH is required for proper segregation of the inner cell mass and trophectoderm cell lineages during mouse development by repressing totipotent and alternative lineage programs. During human embryonic stem cell (hESC) differentiation into germ layer lineages, ERH is crucial for silencing naïve and pluripotency genes, transposable elements, and alternative lineage genes. Strikingly, ERH depletion in somatic cells reverts the H3K9me3 landscape to an hESC state and enables naïve and pluripotency gene and transposable element activation during iPSC reprogramming. Our findings reveal a role for ERH in initiation and maintenance of developmentally established gene repression.
PubMed: 38895478
DOI: 10.1101/2024.06.06.597604 -
International Journal of Molecular... May 2024Derived from axial structures, Sonic Hedgehog (Shh) is secreted into the paraxial mesoderm, where it plays crucial roles in sclerotome induction and myotome...
Derived from axial structures, Sonic Hedgehog (Shh) is secreted into the paraxial mesoderm, where it plays crucial roles in sclerotome induction and myotome differentiation. Through conditional loss-of-function in quail embryos, we investigate the timing and impact of Shh activity during early formation of sclerotome-derived vertebrae and ribs, and of lateral mesoderm-derived sternum. To this end, Hedgehog interacting protein (Hhip) was electroporated at various times between days 2 and 5. While the vertebral body and rib primordium showed consistent size reduction, rib expansion into the somatopleura remained unaffected, and the sternal bud developed normally. Additionally, we compared these effects with those of locally inhibiting BMP activity. Transfection of Noggin in the lateral mesoderm hindered sternal bud formation. Unlike Hhip, BMP inhibition via Noggin or Smad6 induced myogenic differentiation of the lateral dermomyotome lip, while impeding the growth of the myotome/rib complex into the somatic mesoderm, thus affirming the role of the lateral dermomyotome epithelium in rib guidance. Overall, these findings underscore the continuous requirement for opposing gradients of Shh and BMP activity in the morphogenesis of proximal and distal flank skeletal structures, respectively. Future research should address the implications of these early interactions to the later morphogenesis and function of the musculo-skeletal system and of possible associated malformations.
Topics: Animals; Hedgehog Proteins; Ribs; Spine; Gene Expression Regulation, Developmental; Mesoderm; Quail; Somites; Bone Morphogenetic Proteins; Carrier Proteins
PubMed: 38891790
DOI: 10.3390/ijms25115602 -
Cells Jun 2024Patients with chronic hypoxia show a higher tumor incidence; however, no primary common cause has been recognized. Given the similarities between cellular reprogramming...
Patients with chronic hypoxia show a higher tumor incidence; however, no primary common cause has been recognized. Given the similarities between cellular reprogramming and oncogenic transformation, we directly compared these processes in human cells subjected to hypoxia. Mouse embryonic fibroblasts were employed as controls to compare transfection and reprogramming efficiency; human adipose-derived mesenchymal stem cells were employed as controls in human cells. Easily obtainable human peripheral blood mononuclear cells (PBMCs) were chosen to establish a standard protocol to compare cell reprogramming (into induced pluripotent stem cells (iPSCs)) and oncogenic focus formation efficiency. Cell reprogramming was achieved for all three cell types, generating actual pluripotent cells capable for differentiating into the three germ layers. The efficiencies of the cell reprogramming and oncogenic transformation were similar. Hypoxia slightly increased the reprogramming efficiency in all the cell types but with no statistical significance for PBMCs. Various PBMC types can respond to hypoxia differently; lymphocytes and monocytes were, therefore, reprogrammed separately, finding a significant difference between normoxia and hypoxia in monocytes in vitro. These differences were then searched for in vivo. The iPSCs and oncogenic foci were generated from healthy volunteers and patients with chronic obstructive pulmonary disease (COPD). Although higher iPSC generation efficiency in the patients with COPD was found for lymphocytes, this increase was not statistically significant for oncogenic foci. Remarkably, a higher statistically significant efficiency in COPD monocytes was demonstrated for both processes, suggesting that physiological hypoxia exerts an effect on cell reprogramming and oncogenic transformation in vivo in at least some cell types.
Topics: Humans; Cellular Reprogramming; Induced Pluripotent Stem Cells; Cell Transformation, Neoplastic; Animals; Mice; Cell Hypoxia; Leukocytes, Mononuclear; Male; Female; Middle Aged; Fibroblasts; Cell Differentiation; Aged
PubMed: 38891103
DOI: 10.3390/cells13110971 -
Nature Communications Jun 2024Cell-fate decisions during mammalian gastrulation are poorly understood outside of rodent embryos. The embryonic disc of pig embryos mirrors humans, making them a useful... (Comparative Study)
Comparative Study
Cell-fate decisions during mammalian gastrulation are poorly understood outside of rodent embryos. The embryonic disc of pig embryos mirrors humans, making them a useful proxy for studying gastrulation. Here we present a single-cell transcriptomic atlas of pig gastrulation, revealing cell-fate emergence dynamics, as well as conserved and divergent gene programs governing early porcine, primate, and murine development. We highlight heterochronicity in extraembryonic cell-types, despite the broad conservation of cell-type-specific transcriptional programs. We apply these findings in combination with functional investigations, to outline conserved spatial, molecular, and temporal events during definitive endoderm specification. We find early FOXA2 + /TBXT- embryonic disc cells directly form definitive endoderm, contrasting later-emerging FOXA2/TBXT+ node/notochord progenitors. Unlike mesoderm, none of these progenitors undergo epithelial-to-mesenchymal transition. Endoderm/Node fate hinges on balanced WNT and hypoblast-derived NODAL, which is extinguished upon endodermal differentiation. These findings emphasise the interplay between temporal and topological signalling in fate determination during gastrulation.
Topics: Animals; Gastrulation; Endoderm; Swine; Single-Cell Analysis; Gene Expression Regulation, Developmental; Mice; Embryo, Mammalian; Cell Differentiation; Mesoderm; Transcriptome; Hepatocyte Nuclear Factor 3-beta; Cell Lineage; T-Box Domain Proteins; Epithelial-Mesenchymal Transition
PubMed: 38890321
DOI: 10.1038/s41467-024-49407-6 -
Developmental Cell Jun 2024In this issue of Developmental Cell, Bolondi et al. systematically assesses neuro-mesodermal progenitor (NMP) dynamics by combining a mouse stem-cell-based embryo model...
In this issue of Developmental Cell, Bolondi et al. systematically assesses neuro-mesodermal progenitor (NMP) dynamics by combining a mouse stem-cell-based embryo model with molecular recording of single cells, shedding light on the dynamics of neural tube and paraxial mesoderm formation during mammalian development.
Topics: Animals; Mice; Mesoderm; Embryo, Mammalian; Neural Tube; Cell Differentiation; Stem Cells; Body Patterning
PubMed: 38889690
DOI: 10.1016/j.devcel.2024.05.026