Biology subjects

Morrisey, E. E.

Publications and source records attributed to Morrisey, E. E..

10 recordsLinked to original sources

bioRxiv2023

Generation of human alveolar epithelial type I cells from pluripotent stem cells

In the distal lung, alveolar epithelial type I cells (AT1s) comprise the vast majority of alveolar surface area and are uniquely flattened to allow the diffusion of oxygen into the capillaries. This structure along with a quiescent, terminally differentiated phenotype has made AT1s particularly challenging to isolate or maintain in cell culture. As a result, there is a lack of established models for the study of human AT1 biology, and in contrast to alveolar epithelial type II cells (AT2s), little is known about the mechanisms regulating their differentiation. Here we engineer a human in vitro AT1 model system through the directed differentiation of induced pluripotent stem cells (iPSC). We first define the global transcriptomes of primary adult human AT1s, suggesting gene-set benchmarks and pathways, such as Hippo-LATS-YAP/TAZ signaling, that are enriched in these cells. Next, we generate iPSC-derived AT2s (iAT2s) and find that activating nuclear YAP signaling is sufficient to promote a broad transcriptomic shift from AT2 to AT1 gene programs. The resulting cells express a molecular, morphologic, and functional phenotype reminiscent of human AT1 cells, including the capacity to form a flat epithelial barrier which produces characteristic extracellular matrix molecules and secreted ligands. Our results indicate a role for Hippo-LATS-YAP signaling in the differentiation of human AT1s and demonstrate the generation of viable AT1-like cells from iAT2s, providing an in vitro model of human alveolar epithelial differentiation and a potential source of human AT1s that until now have been challenging to viably obtain from patients.

cell biology↗

bioRxiv2022

Atf3 defines a population of pulmonary endothelial cells essential for lung regeneration

Following acute injury, the capillary vascular bed in the lung must be repaired to reestablish gas exchange with the external environment. Little is known about the transcriptional and signaling factors that drive pulmonary endothelial cell (EC) proliferation and subsequent regeneration of pulmonary capillaries, as well as their response to stress. Here, we show that the transcription factor Atf3 is essential for the regenerative response of the mouse pulmonary endothelium after influenza infection. Atf3 expression defines a subpopulation of capillary ECs enriched in genes involved in endothelial development, differentiation, and migration. During lung alveolar regeneration, this EC population expands and increases expression of genes involved in angiogenesis, blood vessel development, and cellular response to stress. Importantly, endothelial cell-specific loss of Atf3 results in defective alveolar regeneration, in part through increased apoptosis and decreased proliferation in the endothelium. This leads to the general loss of alveolar endothelium and persistent morphological changes to the alveolar niche, including an emphysema-like phenotype with enlarged alveolar airspaces lined with regions that lack vascular investment. Taken together, these data implicate Atf3 as an essential component of the vascular response to acute lung injury that is required for successful lung alveolar regeneration.

cell biology↗

bioRxiv2022

Hyperactive mTOR in Lung Mesenchyme Induces Endothelial Dysfunction and Pulmonary Vascular Remodeling

Pulmonary vascular remodeling is the key structural abnormality in pulmonary hypertension (PH). Mechanistic target of rapamycin (mTOR) has long been suspected to play a role in the development of pulmonary vascular remodeling. However, underlying cellular and molecular mechanisms leading to this pathophysiological condition remain incompletely understood. To elucidate the crosstalk between lung mesenchyme with activated mTOR and endothelial cells (ECs), we focused on a monogenic lung disease, pulmonary lymphangioleiomyomatosis (LAM). LAM is a progressive cystic lung disease caused by a mutational inactivation of tuberous sclerosis complex (TSC1/TSC2), which results in constitutive mTOR activation in mesenchymal LAM cells. ECs derived from LAM lung explants showed increased proliferation, migration, and defective angiogenesis compared to age- and sex-matched ECs from control human lung. In LAM cells, we found increased WNT2 ligand expression. We also identified corresponding Frizzled 4 (FZD) receptors on ECs isolated from distal LAM lung, suggesting cellular crosstalk between LAM cells and ECs. In endothelial-fibroblast cocultures, treatment of normal ECs with WNT2 ligands recapitulated LAM EC phenotype and morphology. We observed transcriptomic upregulation in metabolic, angiogenic and growth pathways in ECs of young mice, while 1-year-old Tsc2KO mice spontaneously developed pulmonary vascular remodeling with concurrent elevation in right ventricular systolic pressure. Our study demonstrates that LAM cells are not just a pathological mesenchymal cell state but a signaling hub that contributes to dysregulated cellular response in the surrounding vasculature, eventual pulmonary vascular remodeling and PH.

molecular biology↗

bioRxiv2022

FRIZZLED 2 regulates limb development by mediating both β-catenin-dependent and independent Wnt signaling pathways

Human Robinow Syndrome and omodysplasia, characterized by skeletal limb and craniofacial defects, are associated with mutations in the Wnt receptor FZD2. However, as FZD2 can activate both canonical and non-canonical Wnt pathways, its precise functions and mechanisms of action in limb development are unclear. To address these questions, we generated mice harboring a single nucleotide insertion in the Dishevelled-interacting domain of Fzd2 (Fzd2em1Smill), causing a frameshift mutation similar to the effects of human syndromic FZD2 mutations. Fzd2em1Smill mutant mice had shortened limbs resembling those of Robinow Syndrome and omodysplasia patients. Fzd2em1Smill mutant embryos displayed decreased canonical Wnt signaling in developing limb mesenchyme and disruption of digit chondrocyte elongation and orientation, which is controlled by the WNT5A/PCP pathway. In line with this, we found that tissue-specific disruption of Fzd2 function in limb mesenchyme caused formation of shortened bone elements and was associated with deficiency in both Wnt/{beta}-catenin and WNT5A/PCP signaling. These findings indicate that FZD2 controls limb development by mediating both canonical and non-canonical Wnt pathways and reveal causality of pathogenic FZD2 mutations in Robinow Syndrome and omodysplasia patients. Summary statementHuman FZD2 mutations are associated with limb defects; using genetic mouse models we revealed causality of these mutations and showed that they disrupt both canonical and non-canonical Wnt signaling.

developmental biology↗

bioRxiv2022

Temporal and spatial staging of lung alveolar regeneration is determined by the grainyhead transcription factor Tfcp2l1

Alveolar epithelial type 2 (AT2) cells harbor the facultative progenitor capacity in the lung alveolus to drive regeneration after lung injury. Using single cell transcriptomics, software-guided segmentation of tissue damage, and in vivo lineage tracing, we have identified the grainyhead transcription factor Tfcp2l1 as a key regulator of this regenerative process. Tfcp2l1 expression is initiated late in lung development and restricted to the AT2 cell population in the postnatal lung. Loss of Tfcp2l1 in adult AT2 cells decreased self-renewal and enhanced AT2-AT1 differentiation during active tissue regeneration. Conversely, Tfcp2l1 blunts the proliferative response to inflammatory signaling during the early acute phase after injury. This ability of Tfcp2l1 to temporally regulate the balance of AT2 self-renewal and differentiation is spatially restricted to zones undergoing active alveolar regeneration. Single-cell transcriptomics and lineage tracing reveal that Tfcp2l1 regulates cell fate dynamics by balancing the traffic across the AT2-AT1 differentiation axis and restricting the inflammatory program in AT2 cells. Organoid modeling shows that these cell fate dynamics are controlled by Tfcp2l1 regulation of IL-1 receptor expression and activity in AT2 cells. Together, these studies reveal the critical importance of properly staging lung alveolar regeneration and the integral role of Tfcp2l1 plays in balancing epithelial cell self-renewal and differentiation in this process.

cell biology↗

bioRxiv2022

Guided construction of single cell reference for human and mouse lung

Accurate cell type identification is a key and rate-limiting step in single cell data analysis. Single cell references with comprehensive cell types, reproducible and functional validated cell identities, and common nomenclatures are much needed by the research community to optimize automated cell type annotation and facilitate data integration, sharing, and collaboration. In the present study, we developed a novel computational pipeline to utilize the LungMAP CellCards as a dictionary to consolidate single-cell transcriptomic datasets of 104 human lungs and 17 mouse lung samples and constructed "LungMAP CellRef" and "LungMAP CellRef Seed" for both normal human and mouse lungs. "CellRef Seed" has an equivalent prediction power and produces consistent cell annotation as does "CellRef" but improves computational efficiency and simplifies its utilization for fast automated cell type annotation and online visualization. This atlas set incorporates 48 human and 40 mouse well-defined lung cell types catalogued from diverse anatomic locations and developmental time points. Using independent datasets, we demonstrated the utility of our CellRefs for automated cell type annotation analysis of both normal and disease lungs. User-friendly web interfaces were developed to support easy access and maximal utilization of the LungMAP CellRefs. LungMAP CellRefs are freely available to the pulmonary research community through fast interactive web interfaces to facilitate hypothesis generation, research discovery, and identification of cell type alterations in disease conditions.

bioinformatics↗

bioRxiv2021

LungMAP Portal Ecosystem: Systems-Level Exploration of the Lung

An improved understanding of the human lung necessitates advanced systems models informed by an ever-increasing repertoire of molecular omics, cellular, imaging and pathological datasets. To centralize and standardize information across broad lung research efforts we expanded the LungMAP.net website into a gateway portal. This portal connects a broad-spectrum of research networks, bulk and single-cell multi-omics data and a diverse collection of image data that span mammalian lung development and disease. The data are standardized across species and technologies using harmonized data and metadata models that leverage recent advances including those from the Human Cell Atlas, diverse ontologies, and the LungMAP CellCards initiative. To cultivate future discoveries, we have aggregated a diverse collection of single-cell atlases for multiple species (human, rhesus, mouse), to enable consistent queries across technologies, cohorts, age, disease and drug treatment. These atlases are provided as independent and integrated queriable datasets, with an emphasis on dynamic visualization, figure generation and reference-based classification of user-provided datasets (Azimuth). As this resource grows, we intend to increase the breadth of available interactive interfaces, data portals and datasets from LungMAP and external research efforts.

systems biology↗

bioRxiv2021

Circadian regulation of lung repair and regeneration

Optimal lung repair and regeneration is essential for recovery from viral infections such as that induced by influenza A virus (IAV). We have previously demonstrated that lung inflammation induced by IAV is under circadian control. However, it is not known if the circadian clock exerts its influence on lung repair and regenerative processes independent of acute inflammation from IAV. Here, we demonstrate for the first time that lung organoids have a functional clock as they mature and that the absence of an intact circadian clock impairs regenerative capacity. Using several models of circadian disruption, we show that with the absence of an intact clock lung proliferation is disrupted. Further, we find that the circadian clock acts through direct control of the Wnt/{beta}-catenin pathway. We speculate, that adding the circadian dimension to the critical process of lung repair and regeneration will lead to novel therapies and improve outcomes. Finally, we use data from UK Biobank to demonstrate at the population level, the role of poor circadian rhythms in mediating negative outcomes following lung infection.

cell biology↗

bioRxiv2021

Type II alveolar cells with constitutive expression of MHCII and limited antigen presentation capacity contribute to improved respiratory viral disease outcomes

Type II alveolar cells (AT2s) are critical for basic respiratory homeostasis and tissue repair after lung injury. Prior studies indicate that AT2s also express major histocompatibility complex II (MHCII) molecules, but how MHCII expression by AT2s is regulated and how it contributes to host defense remain unclear. Here we show that AT2s express high levels of MHCII independent of conventional inflammatory stimuli, and that selective loss of MHCII from AT2s in mice results in the worsening of respiratory virus disease following influenza and Sendai virus infections. We also find that AT2s exhibit MHCII presentation capacity that is substantially limited in comparison to professional antigen presenting cells. The combination of constitutive MHCII expression and restrained presentation may position AT2s to contribute to lung adaptive immune responses in a measured fashion, without over-amplifying damaging inflammation.

immunology↗

bioRxiv2020

GSK3 inhibition rescues growth and telomere dysfunction in dyskeratosis congenita iPSC-derived type II alveolar epithelial cells

Dyskeratosis congenita (DC) is a rare genetic disorder characterized by deficiencies in telomere maintenance leading to very short telomeres and the premature onset of certain age-related diseases, including pulmonary fibrosis (PF). PF is thought to derive from epithelial failure, particularly that of type II alveolar epithelial (AT2) cells, which are highly dependent on Wnt signaling during development and adult regeneration. We use human iPSC-derived AT2 (iAT2) cells to model how short telomeres affect AT2 cells. Cultured DC mutant iAT2 cells accumulate shortened, uncapped telomeres and manifest defects in the growth of alveolospheres, hallmarks of senescence, and apparent defects in Wnt signaling. The GSK3 inhibitor, CHIR99021, which mimics the output of canonical Wnt signaling, enhances telomerase activity and rescues the defects. These findings support further investigation of Wnt agonists as potential therapies for DC related pathologies.

cell biology↗