Project description:In the past decades, the paradigm of three germ layers formed by gastrulation has been modified by data suggesting an existence of neuromesodermal progenitors (NMPs) that arise during gastrulation and contribute to both spinal cord and adjacent paraxial mesoderm1-5. However, there lacks direct genetic lineage tracing evidence and functional assessment of NMPs in vivo. Here, we develop a dual recombinases-mediated genetic system to specifically trace and genetically ablate Brachyury+Sox2+ NMPs. Genetic lineage tracing results and single-cell RNA sequencing analysis show that NMPs contain three distinct uni-potent and bi-potent progenitor populations for progressive differentiation into neural and mesodermal fates. Genetic ablation of NMPs by diphtheria toxin reveals a critical role of NMPs in tail formation. This study provides in vivo genetic evidence for heterogeneity of NMPs in their cell fate determination and their functional role in developing embryos.
Project description:TEC progenitors that express beta 5-t contribute to both the cortical and medullary TEC compartments. Our initial experiments across ageing thymi identified a population of potential progenitor TECs which expanded with age, and appears to be a progenitor population for mTEC. These lineage tracing experiments are designed to chart the altered differentiation and senescence of mTEC progenitors with age.
Project description:In the development of the vertebrate body plan, Wnt3a is thought to promote the formation of paraxial mesodermal progenitors (PMPs) of the trunk region while suppressing neural specification. Recent lineage-tracing experiments have demonstrated that these trunk neural progenitors and PMPs derive from a common multipotent progenitor called the neuromesodermal progenitor (NMP). NMPs are known to reside in the anterior primitive streak (PS) region; however, the extent to which NMPs populate the PS and contribute to the vertebrate body plan, and the precise role that Wnt3a plays in regulating NMP self-renewal and differentiation are unclear. To address this, we used cell-specific markers (Sox2 and T) and tamoxifen-induced Cre recombinase-based lineage tracing to locate putative NMPs in vivo. We provide functional evidence for NMP location primarily in the epithelial PS, and to a lesser degree in the ingressed PS. Lineage-tracing studies in Wnt3a/β-catenin signaling pathway mutants provide genetic evidence that trunk progenitors normally fated to enter the mesodermal germ layer can be redirected towards the neural lineage. These data, combined with previous PS lineage-tracing studies, support a model that epithelial anterior PS cells are Sox2(+)T(+) multipotent NMPs and form the bulk of neural progenitors and PMPs of the posterior trunk region. Finally, we find that Wnt3a/β-catenin signaling directs trunk progenitors towards PMP fates; however, our data also suggest that Wnt3a positively supports a progenitor state for both mesodermal and neural progenitors.
Project description:Multicellular systems develop from single cells through a lineage, but current lineage tracing approaches scale poorly to whole organisms. Here we use genome editing to progressively introduce and accumulate diverse mutations in a DNA barcode over multiple rounds of cell division. The barcode, an array of CRISPR/Cas9 target sites, records lineage relationships in the patterns of mutations shared between cells. In cell culture and zebrafish, we show that rates and patterns of editing are tunable, and that thousands of lineage-informative barcode alleles can be generated. By sampling hundreds of thousands of cells from individual zebrafish, we find that most cells in adult zebrafish organs derive from relatively few embryonic progenitors. Genome editing of synthetic target arrays for lineage tracing (GESTALT) will help generate large-scale maps of cell lineage in multicellular systems.
Project description:Developmental origins of dendritic cells (DCs) including conventional DCs (cDCs, comprising cDC1 and cDC2 subsets) and plasmacytoid DCs (pDCs) remain unclear. We studied DC development in unmanipulated adult mice using inducible lineage tracing combined with clonal DNA "barcoding" and single-cell transcriptome and phenotype analysis (CITE-Seq). Inducible tracing of Cx3cr1+ hematopoietic progenitors in the bone marrow showed that they simultaneously produce all DC subsets including pDCs, cDC1s and cDC2s. Clonal tracing of hematopoietic stem cells (HSCs) and of Cx3cr1+ progenitors revealed clone sharing between cDC1s and pDCs, but not between the two cDC subsets or between pDCs and B cells. Accordingly, CITE-Seq analyses of differentiating HSCs and Cx3cr1+ progenitors identified progressive stages of pDC development including Cx3cr1+ Ly-6D+ propDCs that were distinct from lymphoid progenitors. These results reveal the shared origin of pDCs and cDCs, and suggest a revised scheme of DC development whereby pDCs share clonal relationship with cDC1s
Project description:With a genetic clone tracing method (ScarTrace), we labelled early embryonic progenitors and find a strong clonal similarity between spinal cord and mesoderm tissues.
Project description:Isotope tracing analysis to study the intracellular metabolic changes of progenitors during the expansion stage of stress erythropoiesis and assess the effect of 1400w treatment.
Project description:Cardiac fibroblasts convert to myofibroblasts with injury to mediate healing after acute myocardial infarction and to mediate long-standing fibrosis with chronic disease. Myofibroblasts remain a poorly defined cell-type in terms of their origins and functional effects in vivo. Methods: Here we generate Postn (periostin) gene-targeted mice containing a tamoxifen inducible Cre for cellular lineage tracing analysis. This Postn allele identifies essentially all myofibroblasts within the heart and multiple other tissues. Results: Lineage tracing with 4 additional Cre-expressing mouse lines shows that periostin-expressing myofibroblasts in the heart derive from tissue-resident fibroblasts of the Tcf21 lineage, but not endothelial, immune/myeloid or smooth muscle cells. Deletion of periostin+ myofibroblasts reduces collagen production and scar formation after myocardial infarction. Periostin-traced myofibroblasts also revert back to a less activated state upon injury resolution. Conclusions: Our results define the myofibroblast as a periostin-expressing cell-type necessary for adaptive healing and fibrosis in the heart, which arises from Tcf21+ tissue-resident fibroblasts. Fluidigm C1 whole genome transcriptome analysis of lineage mapped cardiac myofibroblasts
Project description:Human ES (H9) cells were directed towards a neuromesodermal progenitor-like cell state and these cells were then subsequently differentiated towards a neural cell fate. Human ES cells (H9) were differentiated into neuromesodermal progenitor-like cells by culturing in Neurobasal/1x N2/1x B27 medium (N2/B27) supplemented with 20 ng/ml bFgf and 3 μM CHIR99021 for 3 days and exposure to dual SMAD inhibition (dSMADi) (Noggin 50 ng/ml and the TGFb receptor type 1 inhibitor SB431542 10 μM) during day 3 (D3). Transcriptome analysis was then carried out following a selection procedure to enrich for NMP-like cells (sD3/NMP-like). This involved use of a hES (H9) cell line engineered with CRISPR-Cas9 to express GFP under the control of the endogenous Nkx1.2 promoter. At the end of day 3 cells were selected for high GFP expression, as high Nkx1.2 transcription is characteristic of NMP cell populations in mouse and chick embryos. These cells were then lysed and RNA extracted for RNASeq. Humans ES cells (H9) differentiated into NMP-like cells as above (without selection) were also allowed to develop further on day 4 (in the presence of dSMADi and Retinoic acid (RA) 100nM, in N2/B27) and then in RA alone until end of day 8 (D8). These cells were then lysed and RNA extracted for RNASeq.