scholarly journals Genomic, epigenomic, and biophysical cues controlling the emergence of the lung alveolus

Science ◽  
2021 ◽  
Vol 371 (6534) ◽  
pp. eabc3172
Author(s):  
Jarod A. Zepp ◽  
Michael P. Morley ◽  
Claudia Loebel ◽  
Madison M. Kremp ◽  
Fatima N. Chaudhry ◽  
...  
Keyword(s):  
Chromatin Accessibility ◽  
Lineage Tracing ◽  
Alveolar Type ◽  
Intercellular Signaling ◽  
Cell Fates ◽  
Pathway Expression ◽  
Biophysical Forces ◽  
Lung Alveolus ◽  
Alveolar Formation

The lung alveolus is the functional unit of the respiratory system required for gas exchange. During the transition to air breathing at birth, biophysical forces are thought to shape the emerging tissue niche. However, the intercellular signaling that drives these processes remains poorly understood. Applying a multimodal approach, we identified alveolar type 1 (AT1) epithelial cells as a distinct signaling hub. Lineage tracing demonstrates that AT1 progenitors align with receptive, force-exerting myofibroblasts in a spatial and temporal manner. Through single-cell chromatin accessibility and pathway expression (SCAPE) analysis, we demonstrate that AT1-restricted ligands are required for myofibroblasts and alveolar formation. These studies show that the alignment of cell fates, mediated by biophysical and AT1-derived paracrine signals, drives the extensive tissue remodeling required for postnatal respiration.

scholarly journals Alterations in alveolar basement membranes during postnatal lung growth.

1982 ◽  
Vol 95 (2) ◽  
pp. 394-402 ◽  
Author(s):  
J S Brody ◽  
C A Vaccaro ◽  
P J Gill ◽  
J E Silbert
Keyword(s):  
Heparan Sulfate ◽  
Ruthenium Red ◽  
Basement Membranes ◽  
Alveolar Type ◽  
Age Related ◽  
Enzyme Degradation ◽  
Alveolar Formation

We studied the ultrastructural characteristics of alveolar basement membranes (ABM) and capillary basement membranes (CBM) in rat lungs at birth, at 8-10 d of age, during alveolar formation, and at 6-10 wk of age, after most alveoli have formed. We also measured in vitro lung proteoglycan and heparan sulfate synthesis at each age. We noted three major age-related changes in pulmonary basement membranes. (a) Discontinuities in the ABM through which basilar cytoplasmic foot processes extend are present beneath alveolar type-2 cells but not alveolar type-1 cells. These discontinuities are most prevalent at birth but also exist in the adult. (b) Discontinuities are also present in CBM at the two earliest time points but are maximal at 8 d of age rather than at birth. Fusions between ABM and CBM are often absent at 8 d of age, but CBM and CBM/ABM fusions were complete in the adult. (c) Heparan sulfate proteoglycans identified with ruthenium red and selective enzyme degradation are distributed equally on epithelial and interstitial sides of the ABM lamina densa at birth, but decrease on the interstitial side with age. In vitro proteoglycan and heparan sulfate accumulation at birth was two times that at 8 d and five times that in the adult. Discontinuities in ABM allow epithelial-mesenchymal interactions that may influence type-2 cells cytodifferentiation. Discontinuities in CBM suggest that capillary proliferation and neovascularization are associated with alveolar formation at 8 d. When CBM becomes complete and forms junctions with ABM, lung neovascularization likely ends as does the ability to form new alveoli.

scholarly journals Intermediary role of lung alveolar type 1 cells in epithelial repair upon Sendai virus infection

2021 ◽  
Author(s):  
Belinda J Hernandez ◽  
Margo P Cain ◽  
Jose R Flores ◽  
Michael J Tuvim ◽  
Burton F Dickey ◽  
...  
Keyword(s):  
Virus Infection ◽  
Single Cell ◽  
Sendai Virus ◽  
Lineage Tracing ◽  
Interferon Response ◽  
Alveolar Type ◽  
Intermediary Role ◽  
Airway Cells

The lung epithelium forms the first barrier against respiratory pathogens and noxious chemicals; however, little is known about how >90% of this barrier—made of alveolar type 1 (AT1) cells—responds to injury, in contrast to our accumulating knowledge of epithelial progenitor and stem cells whose importance lies in their ability to restore the barrier. Using Sendai virus to model natural infection in mice, we combine 3D imaging, lineage-tracing, and single-cell genomics to show that AT1 cells have an intermediary role by persisting in areas depleted of alveolar type 2 (AT2) cells, mounting an interferon response, and receding from invading airway cells. Sendai virus infection mobilizes airway cells to form alveolar SOX2+ clusters without differentiating into AT1 or AT2 cells, as shown in influenza models. Intriguingly, large AT2-cell-depleted areas remain covered by AT1 cells, which we name "AT2-less regions", and are replaced by SOX2+ clusters spreading both basally and luminally around AT1 cell extensions. AT2 cell proliferation and differentiation are largely confined to topologically distal regions—the end of airspace that could be in the periphery or middle of the lung—and form de novo alveolar surface, with limited contribution to in situ repair of AT2-less regions. Time course single-cell RNA-seq and AT1-cell interactome analyses suggest enhanced recognition of AT1 cells by immune cells and altered growth signals. Our comprehensive spatiotemporal and genome-wide study highlights the hitherto unappreciated role of AT1 cells during Sendai virus infection and possibly other injury-repair processes.

scholarly journals Longitudinal single cell transcriptomics reveals Krt8+ alveolar epithelial progenitors in lung regeneration

2019 ◽  
Author(s):  
Maximilian Strunz ◽  
Lukas M. Simon ◽  
Meshal Ansari ◽  
Laura F. Mattner ◽  
Ilias Angelidis ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Lung Injury ◽  
Single Cell ◽  
Progenitor Cell ◽  
Terminal Differentiation ◽  
Lineage Tracing ◽  
Alveolar Type ◽  
Cell State ◽  
Lung Regeneration

Lung injury activates quiescent stem and progenitor cells to regenerate alveolar structures. The sequence and coordination of transcriptional programs during this process has largely remained elusive. Using single cell RNA-seq, we first generated a whole-organ bird’s-eye view on cellular dynamics and cell-cell communication networks during mouse lung regeneration from ∼30,000 cells at six timepoints. We discovered an injury-specific progenitor cell state characterized by Krt8 in flat epithelial cells covering alveolar surfaces. The number of these cells peaked during fibrogenesis in independent mouse models, as well as in human acute lung injury and fibrosis. Krt8+ progenitors featured a highly distinct connectome of receptor-ligand pairs with endothelial cells, fibroblasts, and macrophages. To ‘sky dive’ into epithelial differentiation dynamics, we sequenced >30,000 sorted epithelial cells at 18 timepoints and computationally derived cell state trajectories that were validated by lineage tracing genetic reporter mice. Airway stem cells within the club cell lineage and alveolar type-2 cells underwent transcriptional convergence onto the same Krt8+ progenitor cell state, which later resolved by terminal differentiation into alveolar type-1 cells. We derived distinct transcriptional regulators as key switch points in this process and show that induction of TNF-alpha/NFkappaB, p53, and hypoxia driven gene expression programs precede a Sox4, Ctnnb1, and Wwtr1 driven switch towards alveolar type-1 cell fate. We show that epithelial cell plasticity can induce non-gradual transdifferentiation, involving intermediate progenitor cell states that may persist and promote disease if checkpoint signals for terminal differentiation are perturbed.

scholarly journals Transcriptional regulatory networks that promote and restrict identities and functions of intestinal innate lymphoid cells

2018 ◽  
Author(s):  
Maria Pokrovskii ◽  
Jason A. Hall ◽  
David E. Ochayon ◽  
Ren Yi ◽  
Natalia S. Chaimowitz ◽  
...  
Keyword(s):  
Regulatory Networks ◽  
Inflammatory Diseases ◽  
Innate Lymphoid Cells ◽  
Chromatin Accessibility ◽  
Immune Defense ◽  
Lymphoid Cells ◽  
Transcriptional Regulatory Networks ◽  
Transcriptional Regulatory

SummaryInnate lymphoid cells (ILCs) can be subdivided into several distinct cytokine-secreting lineages that promote tissue homeostasis and immune defense but also contribute to inflammatory diseases. Accumulating evidence suggests that ILCs, similarly to other immune populations, are capable of phenotypic and functional plasticity in response to infectious or environmental stimuli. Yet the transcriptional circuits that control ILC identity and function are largely unknown. Here we integrate gene expression and chromatin accessibility data to infer transcriptional regulatory networks within intestinal type 1, 2, and 3 ILCs. We predict the “core” sets of transcription-factor (TF) regulators driving each ILC subset identity, among which only a few TFs were previously known. To assist in the interpretation of these networks, TFs were organized into cooperative clusters, or modules that control gene programs with distinct functions. The ILC network reveals extensive alternative-lineage-gene repression, whose regulation may explain reported plasticity between ILC subsets. We validate new roles for c-MAF and BCL6 as regulators affecting the type 1 and type 3 ILC lineages. Manipulation of TF pathways identified here might provide a novel means to selectively regulate ILC effector functions to alleviate inflammatory disease or enhance host tolerance to pathogenic microbes or noxious stimuli. Our results will enable further exploration of ILC biology, while our network approach will be broadly applicable to identifying key cell state regulators in otherin vivocell populations.

scholarly journals Cells of NG2 lineage increase in glomeruli of mice following podocyte depletion

2018 ◽  
Vol 315 (5) ◽  
pp. F1449-F1464 ◽  
Author(s):  
Taihei Suzuki ◽  
Diana G. Eng ◽  
Aaron D. McClelland ◽  
Jeffrey W. Pippin ◽  
Stuart J. Shankland
Keyword(s):  
Epithelial Cell ◽  
Cell Types ◽  
Lineage Tracing ◽  
Cell Fates ◽  
Kinase Substrate ◽  
Parietal Epithelial Cell ◽  
Fluorescence Protein ◽  
Red Fluorescence Protein ◽  
Podocyte Proteins ◽  
Parietal Epithelial Cells

Under certain circumstances, podocytes can be partially replaced following their loss in disease. The inability of podocytes to proliferate suggests that replacement derives from other cell types. Because neural/glial antigen 2 (NG2)-expressing cells can serve as progenitors in other organs and because herein we showed increased NG2 staining in podocytes following their loss in experimental focal segmental glomerulosclerosis, we used lineage tracing in NG2-CreER tdTomato mice to test the hypothesis that partial podocyte replacement might derive from this cell population. The percentage of glomeruli with red fluorescence protein (RFP)-labeled NG2 cells increased following podocyte depletion, which was augmented by enalapril. However, BrdU was not detected in RFP-labeled cells, consistent with the migration of these cells to the glomerulus. Within glomeruli, RFP-labeled cells did not coexpress podocyte proteins (p57, synaptopodin, nephrin, or podocin) but did coexpress markers for mesangial (α8 integrin, PDGFβ receptor) and parietal epithelial cells (PAX8, src-suppressed C-kinase substrate). These results suggest that following podocyte depletion, cells of NG2 lineage do not serve as adult podocyte progenitors but have the ability to transdifferentiate to mesangial and parietal epithelial cell fates.

Transformation of alveolar Type 2 cells to Type 1 cells following exposure to NO2

1975 ◽  
Vol 22 (1) ◽  
pp. 142-150 ◽  
Author(s):  
Michael J. Evans ◽  
Linda J. Cabral ◽  
Robert J. Stephens ◽  
Gustave Freeman
Keyword(s):  
Alveolar Type

scholarly journals H 2 0 2 regulates lung ENaC via ubiquitin‐like protein Nedd8 in alveolar type 1 and type 2 cells.

2013 ◽  
Vol 27 (S1) ◽  
Author(s):  
Nicholle M. Johnson ◽  
Charles A. Downs ◽  
Lisa H. Kreiner ◽  
My N. Helms
Keyword(s):  
Alveolar Type

scholarly journals Reversal of autoimmunity by mixed chimerism enables reactivation of β cells and transdifferentiation of α cells in diabetic NOD mice

2020 ◽  
Vol 117 (49) ◽  
pp. 31219-31230
Author(s):  
Shanshan Tang ◽  
Mingfeng Zhang ◽  
Samuel Zeng ◽  
Yaxun Huang ◽  
Melissa Qin ◽  
...  
Keyword(s):  
Nod Mice ◽  
Lineage Tracing ◽  
Mixed Chimerism ◽  
Cell Regeneration ◽  
Β Cells ◽  
Β Cell ◽  
Nonobese Diabetic ◽  
Autoimmune Destruction ◽  
Epidermal Growth

Type 1 diabetes (T1D) results from the autoimmune destruction of β cells, so cure of firmly established T1D requires both reversal of autoimmunity and restoration of β cells. It is known that β cell regeneration in nonautoimmune diabetic mice can come from differentiation of progenitors and/or transdifferentiation of α cells. However, the source of β cell regeneration in autoimmune nonobese diabetic (NOD) mice remains unclear. Here, we show that, after reversal of autoimmunity by induction of haploidentical mixed chimerism, administration of gastrin plus epidermal growth factor augments β cell regeneration and normalizes blood glucose in the firmly established diabetic NOD mice. Using transgenic NOD mice with inducible lineage-tracing markers for insulin-producing β cells, Sox9+ductal progenitors, Nestin+mesenchymal stem cells, and glucagon-producing α cells, we have found that both reactivation of dysfunctional low-level insulin expression (insulinlo) β cells and neogenesis contribute to the regeneration, with the latter predominantly coming from transdifferentiation of α cells. These results indicate that, after reversal of autoimmunity, reactivation of β cells and transdifferentiation of α cells can provide sufficient new functional β cells to reach euglycemia in firmly established T1D.

Sign in / Sign up

Export Citation Format

Share Document