Project description:Early postnatal myofibroblasts are a key cell type involved in postnatal alveolarization. The majority of these cells undergo apoptosis post-alveolarization. However, some dedifferntaite and persist in the adult lung. We utilized single cell RNA seq. to understand transcriptomics of these persisted myofibroblasts.
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:Lung myofibroblasts are necessary for early postnatal alveolar growth. The unique contributions of individual myofibroblast lineages to alveolar development is unresolved by existing genetic tools. We generated a Stc1CreERT2 mouse line that labels the developmentally transient secondary crest myofibroblasts (SCMFs), distinguishing them from alveolar duct myofibroblasts (DMF) and smooth muscle. SCMFs expand through clonal proliferation of Stc1-expressing progenitors and are cleared by apoptosis. Deleting the apoptosis effectors Bax and Bak1 in the Stc1-lineage prevented SCMF clearance during alveologenesis. Single-cell RNA sequencing showed that surviving Stc1-lineage cells lose myofibroblast identity while coexpressing SCMF and DMF markers. Embryonic lineage tracing identified distinct progenitors for SCMFs and DMFs, and genetic activation of Hedgehog (Hh) or Wnt signaling pathways failed to interconvert these lineages. These findings establish Stc1-lineage SCMFs as a discrete, developmentally divergent population, and define their life cycle independent of other myofibroblast lineages.
Project description:VSMCs expressing SCA1 have increased proliferative capacity (Dobnikar et al, 2018; Worssam et al, 2022; Pan et al, 2020). We therefore, mapped chromatin accessibility changes using bulk ATAC-seq for SCA1+ and SCA1- lineage traced VSMCs.
Project description:In the first three weeks postnatally, the pituitary gland undergoes a period of rapid growth, due to both cell proliferation and endocrine cell size increase. SCs are initially the most proliferative, and lineage tracing experiments previously showed that neonatal SCs can give rise to all endocrine cell types. However, because the Cre drivers used for lineage tracing were relatively inefficient and relied on tamoxifen, a selective estrogen receptor modulator which perturbs normal physiology, we could not decipher SC contribution to organ growth. We have thus performed lineage tracing using a new, more efficient and physiologically neutral Sox2rtTA allele. When we traced early postnatal SCs using Sox2rtTA, we observed, similarly in both sexes, that most adult gonadotrophs derive from this neonatal SC population. These observations were confirmed and complemented by a single cell RNAseq dataset from postnatal day 3 (PND3) SOX9iresGFP XX and XY positive cells. From SOX9iresGFP cells, which comprise SCs and their immediate progeny, cell trajectories were inferred, and relevant gene regulatory networks predicted. Along with lineage tracing experiments, this dataset confirmed that SCs mostly differentiate into gonadotrophs postnatally. As animals develop, SC-derived gonadotrophs invade the gland, while the minor embryonic population remains confined ventrally. The discovery of a dual origin for gonadotrophs may help understand aspects of gonadotrophin regulation and mechanisms of diseases affecting puberty and fertility.
Project description:Stem cells are defined by two cardinal properties: limitless self-renewal and multipotency. We have serendipitously found that non-haematopoietic DNGR-1 lineage traced cells residing in the ependymal cell layer of the central nervous system display the two cardinal properties of stem cells, both in vitro and in vivo. However, whether these properties were a feature of all DNGR-1-traced cells or were confined to a particular subset of these is unclear. To address the potential heterogeneity of DNGR-1-traced ependymal cells and caractherise their putative stem cell compartment we conducted single-cell RNA sequencing of DNGR-1-traced cells isolated from uninjured spinal cords.
Project description:Using CD133 as a pan-ependymal cell marker, we wished to understand whether CD133+ DNGR-1 traced cells constituted a distinct subset of ependymal cells by comparing these at the single cell level with CD133+ non-traced cells purified from spinal cords of DNGR-1 lineage tracer mice.
Project description:Alveolar myofibroblasts emerge during postnatal lung development and are substantially cleared following the completion of the alveolar stage of lung development. In this study, we hypothesized that alveolar myofibroblast descendants that escape apoptotic clearance are reactivated in resposne to injury during adult life.